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The discrimination and recognition of biological targets, such as proteins, cells, and bacteria, are of utmost importance in various fields of biological research and production. These include areas like biological medicine, clinical diagnosis, and microbiology analysis. In order to efficiently and cost-effectively identify a specific target from a wide range of possibilities, researchers have developed a technique called differential sensing. Unlike traditional “lock-and-key” sensors that rely on specific interactions between receptors and analytes, differential sensing makes use of cross-reactive receptors. These sensors offer less specificity but can cross-react with a wide range of analytes to produce a large amount of data. Many pattern recognition strategies have been developed and have shown promising results in identifying complex analytes. To create advanced sensor arrays for higher analysis efficiency and larger recognizing range, various nanomaterials have been utilized as sensing probes. These nanomaterials possess distinct molecular affinities, optical/electrical properties, and biological compatibility, and are conveniently functionalized. In this review, our focus is on recently reported optical sensor arrays that utilize nanomaterials to discriminate bioanalytes, including proteins, cells, and bacteria.

DNA origami is a promising technology for its reproducibility, flexibility, scalability and biocompatibility. Among the several potential applications, DNA origami has been proposed as a tool for drug delivery and as a contrast agent, since a conformational change upon specific target interaction may be used to release a drug or produce a physical signal, respectively. However, its conformation should be robust with respect to the properties of the medium in which either the recognition or the read-out take place, such as pressure, viscosity and any other unspecific interaction other than the desired target recognition. Here we report on the read-out robustness of a tetragonal DNA-origami/gold-nanoparticle hybrid structure able to change its configuration, which is transduced in a change of its plasmonic properties, upon interaction with a specific DNA target. We investigated its response when analyzed in three different media: aqueous solution, solid support and viscous gel. We show that, once a conformational variation is produced, it remains unaffected by the subsequent physical interactions with the environment.

Abstract Cancer ranks as a leading cause of death and a huge obstacle to rising life expectancy. If cancers are spotted early there's a high chance of survival. The conventional methods relying on the phenotypic features of the tumor are not powerful to the early screening of cancer. Cancer biomarkers are capable of indicating specific cancer states. Current biochemical assay suffers from time and reagents consuming and discontinuous monitoring. Surface plasmon resonance (SPR) technology, a refractive index-based optical biosensor, has significant promise in biomarker detection because of its outstanding features of label-free, sensitivity, and reliability. The nanomaterial features exotic physical and chemical property work on the process of transferring biorecognition event into SPR signal and hence is functioned as signal enhancer. In this review, we mainly discussed the mechanism of gold nanoparticles (AuNPs) and two-dimensional (2D) functional nanomaterial for improving the SPR signal. We also introduced AuNPs and 2D nanomaterial assisted SPR technology in determining cancer biomarker. Last but not least, we discussed the challenges and outlooks of the aforementioned reformative SPR technology for cancer biomarker determination in the clinical trial.

The identification of tumor-related microRNAs (miRNAs) exhibits excellent promise for the early diagnosis of cancer and other bioanalytical applications. Therefore, we developed a sensitive and efficient biosensor using polyadenine (polyA)-mediated fluorescent spherical nucleic acid (FSNA) for miRNA analysis based on strand displacement reactions on gold nanoparticle (AuNP) surfaces and electrokinetic signal amplification (ESA) on a microfluidic chip. In this FSNA, polyA-DNA biosensor was anchored on AuNP surfaces via intrinsic affinity between adenine and Au. The upright conformational polyA-DNA recognition block hybridized with 6-carboxyfluorescein-labeled reporter-DNA, resulting in fluorescence quenching of FSNA probes induced by AuNP-based resonance energy transfer. Reporter DNA was replaced in the presence of target miRNA, leading to the recovery of reporter-DNA fluorescence. Subsequently, reporter-DNAs were accumulated and detected in the front of with Nafion membrane in the microchannel by ESA. Our method showed high selectivity and sensitivity with a limit of detection of 1.3 pM. This method could also be used to detect miRNA-21 in human serum and urine samples, with recoveries of 104.0%–113.3% and 104.9%–108.0%, respectively. Furthermore, we constructed a chip with three parallel channels for the simultaneous detection of multiple tumor-related miRNAs (miRNA-21, miRNA-141, and miRNA-375), which increased the detection efficiency. Our universal method can be applied to other DNA/RNA analyses by altering recognition sequences.

Objective(s): Surgery and radiation therapy are the most important known treatments for glioblastoma, which is known as the most malignant tumor of the central nervous system. Numerous studies have proven the effect of different gold nanoparticles in improving radiation sensitivity. But there is still a need for nanoparticles with suitable size and higher sensitivity. Hence, the present study aimed to prepare optimized glucose-coated gold nanoparticles (Glu-GNPs) for improving radiosensitivity against U87 glioblastoma cells.Materials and Methods: Firstly, Glu-GNPs were synthesized and then their physiochemical characterizations were assessed using dynamic light scattering (DLS). The cytotoxicity of Glu-GNPs was evaluated by MTT assay in U87 and NIH-3T3 cell lines. Additionally, the colony formation assay, which is known as the gold standard test, was used to evaluate the radiosensitivity effect of Glu-GNPs on U87 cells.Results: The characterization results showed that Glu-GNPs had a size of 50.3 nm and negative zeta potential of -13.8 mV. Cytotoxicity results revealed that treatment with Glu-GNPs significantly inhibited the proliferation of U87 cells. We found that Glu-GNPs at a concentration of 10 μg/ml were not-toxic for U87 cells. Moreover, the colony formation assay results showed that Glu-GNPs significantly increased the effect of radiation and caused U87 cancer cell death at a non-toxic concentration of 10 μg/ml.Conclusion: Taken together, the Glu-GNPs, with a size of 50.3 nm, increased radiosensitivity and caused cell death at a concentration of 10 µg/ml in U87 glioblastoma cells and deserve further in vitro and in vivo investigations.

Abstract Highly sensitive, simple and reliable colorimetric probe for Cu2+-ion detection was visualized with the L-cysteine functionalized gold nanoparticle (LS-AuNP) probes. The pronounced sensing of Cu2+ with high selectivity was rapidly featured with obvious colour change that enabled to visually sense Cu2+ ions by naked eyes. By employing systemic investigations on crystallinities, elemental compositions, microstructures, surface features, light absorbance, zeta potentials and chemical states of LS-AuNP probes, the oxidation-triggered aggregation effect of LS-AuNP probes was envisioned. The results indicated that the mediation of Cu2+ oxidation coordinately caused the formation of disulfide cystine, rendering the removal of thiol group at AuNPs surfaces. These features reflected the visual colour change for the employment of tracing Cu2+ ions in a quantitative way.

The electrochemical behavior of captopril at the surface of a carbon-paste electrode (CPE) modified with gold nanoparticles (GNPs) is described. The prepared electrode shows an excellent electrocatalytic activity toward the oxidation of captopril, which is leading to marked considerable improvement of sensitivity. Whereas at the surface of unmodified electrode an electrochemical activity for captopril cannot be observed, a very sharp anodic wave with an anodic peak potential about 1.0V (versus Ag/AgCl) is obtained using the prepared modified electrode. Captopril oxidation on CPE/GNPs proceeds at pH between 4.0 and 10.0. Under the optimized conditions, the electrocatalytic oxidation peak current of captopril showed two linear dynamic ranges with a detection limit of 8.28×10-2 µM captopril. The linear calibration range was 1.14-16.98 and 21.49-62.1 µM using amperometric. Finally, the sensor was examined as a selective, simple, and precise new electrochemical sensor for the determination of captopril in pharmaceutical samples including tablets and satisfactory results were obtained.

Abstract Titanium oxide (TiO2)-based photocatalysts are one of the most promising materials that can reduce carbon dioxide (CO2) by utilizing sunlight, thus reducing CO2 concentration in the air. In this study, we develop a simple and practical one-pot synthesis method to prepare photocatalysts with Au nanoparticles (AuNPs) supported on mixtures of titanium oxide and calcium carbonate (CaCO3). By synthesizing a lot of smaller AuNPs and supporting them on the surface of the photocatalyst, it is possible to enhance the surface area of AuNPs, improving the photocatalytic performance of carbon dioxide reduction. The synthesized photocatalysts with fixed TiO2 content and varied CaCO3 fractions between 0 and 200 wt% are characterized through X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and ultraviolet–visible spectroscopy. The size of AuNPs in the photocatalyst with CaCO3 is smaller than that in the photocatalyst without CaCO3, and the density of AuNPs per catalyst area in the photocatalyst with 40 wt% CaCO3 is approximately 200 times higher than that of the photocatalyst without CaCO3. With the addition of CaCO3, the yields of CO and CH4 increase by 2.9–4.0 and 1.3–2.1 times, respectively. Article highlights Photocatalysts using Au nanoparticles supported on TiO2 and CaCO3 are prepared using a simple one-pot synthesis method. The ratio of CaCO3 to TiO2 is changed and specific Au nanoparticles with a small size and a large number are synthesized when 40 wt% of CaCO3 was added. Photocatalysts with smaller Au nanoparticles and larger Au surface area produce more CO and CH4.

Transplanted cells rarely survive because of the inflammatory cytokines after spinal cord injury. To increase the survival, we synthesized a hydrophilic and aligned nanofibrous mat. We electrospun thiolate (SH)/aligned (A) poly(lactic-co-glycolic acid) (PLGA) nanofibrous mats. The PLGA-SH (A) nanofibrous mats were conjugated with gold nanoparticles (GNPs) to increase the hydrophilicity. The contact angle is decreased from 105.3° ± 5.2 (for randomly directional PLGA mats) to 28.1° ± 2.8 (for PLGA-GNP (A) mats). Green fluorescent protein (GFP)-expressing neural progenitor cells (NPCs) were dissociated from the embryonic spinal cords of Fisher 344 rats. We embedded the embryonic spinal-cord-derived NPCs in glycol chitosan (gC)-oxidized hyaluronate (oHA) hydrogels (=NPC graft). The NPC graft was transplanted into spinal-cord-injured Sprague-Dawley rats. Afterwards, the aligned PLGA-GNP nanofibrous mat was positioned onto the NPC-grafted region (=Injury + NPC graft + PLGA-GNP (A) nanofibrous mat (INP) group). We also added Injury (=I) and Injury + NPC graft (=IN) groups as control groups. The survival outcomes of transplanted NPCs were noticeably increased in the INP group compared to those in the IN group. We suggest a separate implanting therapy of NPCs and a hydrophilic PLGA-GNP (A) nanofibrous mat for spinal cord injuries.

Tuberculosis (TB) is one of the deadliest diseases in Africa and it is classified as a serious global health problem. A new threat associated with the disease is the emergence of multidrug-resistant TB (MDR-TB), which results from improper dose or non-compliance with a treatment regime. It is, therefore, important to determine a patient’s rate of TB drug metabolism at a point-of-care, in order to enable appropriate dose prescription. This work presents a novel enzymatic nanobiosensor for real-time determination of isoniazid (INH), which is a highly prescribed drug for TB treatment. The nanobiosensor consists of a cytochrome P450-2E1 (CYP2E1) isoenzyme covalently attached to a screen printed or disk gold electrode (Au), functionalized with thioglycolic acid-capped gold nanoparticle (TGA-AuNP). The nanomaterial was green-synthesized with banana peel extract (BPE) as the reducing agent. It exhibited an ultraviolet-visible spectroscopy (UV–Vis) signature absorption band for AuNP at 536 nm and a direct bandgap energy (Eg) value of 2.00 eV. Fourier transform infra-red spectroscopy (FTIR) was used to confirm the reduction of Au3+ to Au0. High-resolution transmission electron microscopy (HR-TEM) and high-resolution scanning electron microscopy (HR-SEM) studies indicated that TGA-AuNPs were polydisperse and exhibited spherical morphology. Bovine serum albumin (BSA) and CYP2E1 were attached to the TGA-AuNPs-modified Au electrode using glutaraldehyde (Glu) as binder, to form the nanobiosensor (BSA/CYP2E1/Glu/TGA-AuNPs/Au). Differential pulse voltammetric (DPV) responses of the nanobiosensor for INH were determined in 10 mM phosphate buffer (pH 7.4). The limit of detection (LOD) and the limit of quantification (LOQ) values of the nanobiosensor were 0.0556 μM INH and 0.1683 μM INH, respectively.

Abstract Plasmonic nanomaterials have attracted much attention to new anticounterfeiting technology. Since one of current anticounterfeiting problems is fake medical tablets, on‐dose authentication of the tablets is strongly required considering tiny area of tablets, biocompatibility, and long shelf life. Previously, Nanotags consisting of self‐assemblies of colloidal gold nanoparticles with reporter molecules were proposed, which produce characteristic surface enhanced Raman scattering (SERS) activity. However, long‐term stability is rarely discussed for SERS active nanostructures. This study deposits about 10 ng of the Nanotags on a very tiny area of the commercial tablets. Distinguishable SERS signals of reporting molecules are confirmed by 1s irradiation of 785 nm laser over the Nanotags, while Raman spectrum of the ingredients is observed on the tablet without the Nanotags. Rapid authentication of tablets stocked over 8 years is sufficiently carried out. In addition, the Nanotags on the tablets are almost invisible to the eye, in particular, if the tablet surface is uneven or colored. It is considered that the presence of discrete AuNP assemblies allows excellent performances of Nanotag.

Eco-friendly chemical methods using FDA-approved Pluronic F127 (PLU) block copolymer have garnered much attention for simultaneously forming and stabilizing Au nanoparticles (AuNPs). Given the remarkable properties of AuNPs for usage in various fields, especially in biomedicine, we performed a systematic study to synthesize AuNP-PLU nanocomposites under optimized conditions using UV irradiation for accelerating the reaction. The use of UV irradiation at 254 nm resulted in several advantages over the control method conducted under ambient light (control). The AuNP-PLU-UV nanocomposite was produced six times faster, lasting 10 min, and exhibited lower size dispersion than the control. A set of experimental techniques was applied to determine the structure and morphology of the produced nanocomposites as affected by the UV irradiation. The MTT assay was conducted to estimate IC50 values of AuNP-PLU-UV in NIH 3T3 mouse embryonic fibroblasts, and the results suggest that the sample is more compatible with cells than control samples. Afterward, in vivo maternal and fetal toxicity assays were performed in rats to evaluate the effect of AuNP-PLU-UV formulation during pregnancy. Under the tested conditions, the treatment was found to be safe for the mother and fetus. As a proof of concept or application, the synthesized Au:PLU were tested as contrast agents with an X-ray computed tomography scan (X-ray CT). [ABSTRACT FROM AUTHOR]

In the present study, the various concentrations of AuNP (1.25, 2.5, 5, 10 ppm) were prepared to investigate the biocompatibility, biological performances and cell uptake efficiency via Wharton's jelly mesenchymal stem cells and rat model. The pure AuNP, AuNP combined with Col (AuNP-Col) and FITC conjugated AuNP-Col (AuNP-Col-FITC) were characterized by Ultraviolet–visible spectroscopy (UV-Vis), Fourier-transform infrared spectroscopy (FTIR) and Dynamic Light Scattering (DLS) assays. For in vitro examinations, we explored whether the Wharton's jelly MSCs had better viability, higher CXCR4 expression, greater migration distance and lower apoptotic-related proteins expression with AuNP 1.25 and 2.5 ppm treatments. Furthermore, we considered whether the treatments of 1.25 and 2.5 ppm AuNP could induce the CXCR4 knocked down Wharton's jelly MSCs to express CXCR4 and reduce the expression level of apoptotic proteins. We also treated the Wharton's jelly MSCs with AuNP-Col to investigate the intracellular uptake mechanisms. The evidence demonstrated the cells uptake AuNP-Col through clathrin-mediated endocytosis and the vacuolar-type H+-ATPase pathway with good stability inside the cells to avoid lysosomal degradation as well as better uptake efficiency. Additionally, the results from in vivo examinations elucidated the 2.5 ppm of AuNP attenuated foreign body responses and had better retention efficacy with tissue integrity in animal model. In conclusion, the evidence demonstrates that AuNP shows promise as a biosafe nanodrug delivery system for development of regenerative medicine coupled with Wharton's jelly MSCs. [ABSTRACT FROM AUTHOR]

Cancer treatment using ultrasound irradiation with low intensities along with a sonosensitizer has been found to have significant advantages, such as high penetration depth in tissues, non-invasive therapeutic character, minor side effects, good patient adherence and preferential tumor area treatment. In the present study, gold nanoparticles covered by poly(ortho-aminophenol) (Au@POAP NPs) were synthesized and characterized as a new sonosensitizer. We investigated Au@POAP NPs efficacy on fractionated ultrasound irradiation for treatment of melanoma cancer in vitro as well as in vivo. In vitro examinations revealed that although Au@POAP NPs (with a mean size of 9.8 nm) alone represented concentration-dependent cytotoxicity against the B16/F10 cell line, multistep ultrasound irradiation (1 MHz frequency, 1.0 W/cm2 intensity, 60 s irradiation time) of the cells in the attendance of Au@POAP NPs led to efficient cell sonodynamic therapy (SDT) and death. Histological analyses revealed that in vivo fractionated SDT toward melanoma tumors of male balb/c mice led to no residual viable tumor cell after 10 d. A deep sonosensitizing effectiveness of Au@POAP NPs on fractionated low-intensity ultrasound irradiation was attained with the main mechanism of tumor cell eradication of promotion of apoptosis or necrosis through dramatically increased reactive oxygen species levels. [ABSTRACT FROM AUTHOR]

Gold nanoparticle (GNP) was prepared in situ using poly(ethylenimine)/(phenylthio) acetic acid(PEI/PTA) ion pair self-assembly(IPSAM) as a reducing and a capping material. The upper critical solution temperature of the ion pair was affected by the addition of gold ions. Gold ion could be converted to GNP in the IPSAM suspension by aging for 60–150 min. The aging period was shorter and the surface plasmon resonance signal of GNP was stronger as the ion concentration (0.5 and 2.5 mM) and the temperature (20, 30, and 40 °C) were higher. X-ray photoelectron spectroscopy revealed that gold existed with the PEI/PTA IPSAM as a metallic state after 24 h aging. A transmission electron microscopy revealed that GNP existed on the inside of the IPSAM and the lattice spacing of GNP was about 0.20 nm. The release degree of nile red loaded in the IPSAM under near-infrared (NIR) irradiation was proportional to the GNP content. The maximum release degree for 60 min was about 5.7, 6.5, 17.6, 32.4, and 41.2%, respectively, when the GNP content was 0, 0.25, 0.35, 0.6, and 1.55%. The IPSAM containing GNP would be used as a drug carrier that releases its cargo in answering to NIR irradiation. [ABSTRACT FROM AUTHOR]

Adenosine as a potential tumor marker is of great value for clinical disease diagnosis. Since the CRISPR-cas12a system is only capable of recognizing nucleic acid targets we expanded the CRISPR-cas12a system to determine small molecules by designing a duplexed aptamer (DA) converting g-RNA recognition of adenosine to recognition of aptamer complementary DNA strands (ACD). To further improve the sensitivity of determination, we designed a molecule beacon (MB)/gold nanoparticle (AuNP)-based reporter, which has higher sensitivity than traditional ssDNA reporter. In addition, the AuNP-based reporter enables more efficient and fast determination. The determination of adenosine under 488-nm excitation can be realized within 7 min, which is more than 4 times faster than traditional ssDNA reporter. The linear determination range of the assay to adenosine was 0.5–100 μM with the determination limit of 15.67 nM. The assay was applied to recovery determination of adenosine in serum samples with satisfactory results. The recoveries were between 91 and 106% and the RSD values of different concertation were below 4.8%. This sensitive, highly selective, and stable sensing system is expected to play a role in the clinical determination of adenosine and other biomolecules. [ABSTRACT FROM AUTHOR]

The incidence of Mycobacterium tuberculosis (MTB) is increasing due to lack of appropriate diagnostic and therapeutic methods. Therefore, early and accurate detection of this bacteria plays a significant role in controlling tuberculosis. This study aimed to design, develop, and implement a direct and rapid detection method of MTB using modified gold nanoparticle (AuNP) colorimetric probe-based biosensor in sputum specimens. Spherical AuNPs were synthesized by the citrate reduction method and were functionalized using thiol-modified oligonucleotides (AuNP-biosensor). AuNP-biosensor and IS6110 PCR were compared to the gold standard in terms of analytical and clinical sensitivity and specificity, positive predictive value (PPV), negative predictive value (NPV), diagnostic odds ratio (DOR), and accuracy in 52 clinical specimens. Gold standard was defined as a positive result in concentrated sputum smear microscopy (SSM), culture, or Xpert MTB/RIF. The AuNP-biosensor had 100% sensitivity and specificity for detection of total sputum DNA in less than 15 min with ready-to-use AuNP-biosensor. PPV, NPV, DOR and accuracy of this method were 100%, 100%, 2325 and 100%, respectively. Considering the promising results of the diagnostic value indices of the AuNP-biosensor, the designed method is an affordable, rapid, reliable, and cost-beneficial way for direct detection of MTB in sputum specimens. [ABSTRACT FROM AUTHOR]

Water resources of our earth is currently facing a serious challenge due to human activities including industrial development, agricultural revolution, urban growth and deforestation. The first step for pollutant removal is obviously their detection in water which requires use of various well known instrumentation techniques or use of sensors. Of all the different types of sensors, gold and silver nanoparticle based colorimetric/plasmonic nano-sensors are particularly noteworthy because of their simplicity and low cost. These nano-sensors are based on principle of SPR, an optical phenomenon immensely dependent on characteristics of the nanoparticles. Noble metal nanoparticles are widely chosen for colorimetric sensing application as their SPR absorbance lie in the visible region of spectrum rendering unique colors to them. Also, they are easy to synthesize, easy to functionalize, biocompatible and stable. In this detection technique, the presence of a pollutant is revealed by a distinct, visual color change and can also be quantified using a UV-Visible Spectrophotometer. Sustainable chemistry being one of the focal points of modern chemistry research, green synthesis of nanoparticles, particularly noble metal nanoparticles such as gold and silver have attracted considerable attention in last decade. Although gold and silver nanoparticles based optical sensor have been summarized in various reviews over last few years, colorimetric nano-sensors synthesized by green methods have found little discussion in scientific literature. This critical review aims to connect this gap by portraying this sparsely explored area of application of biosynthesized silver and gold nanoparticles and thus will assist the researchers working in this field. Green synthesis of silver and gold nanoparticles Colorimetric detection of environmental pollutants Metal mediated aggregation Redox etching Selectivity, sensitivity and Limit of Detection [ABSTRACT FROM AUTHOR]

Rapid, sensitive, and reliable detection of high mobility group box 1 (HMGB1) is essential for medical and diagnostic applications due to its important role as a biomarker of chronic inflammation. Here, we report a facile method for the detection of HMGB1 using carboxymethyl dextran (CM-dextran) as a bridge molecule modified on the surface of gold nanoparticles combined with a fiber optic localized surface plasmon resonance (FOLSPR) biosensor. Under optimal conditions, the results showed that the FOLSPR sensor detected HMGB1 with a wide linear range (10−10 to 10−6 g/mL), fast response (less than 10 min), and a low detection limit of 43.4 pg/mL (1.7 pM) and high correlation coefficient values (>0.9928). Furthermore, the accurate quantification and reliable validation of kinetic binding events measured by the currently working biosensors are comparable to surface plasmon resonance sensing systems, providing new insights into direct biomarker detection for clinical applications. [ABSTRACT FROM AUTHOR]

8-Oxo-7,8-dihydro-2′-deoxyguanosine (8-oxo-dG) is a crucial biomarker of oxidative DNA damage. Herein, a highly sensitive fluorescent aptasensor for detecting 8-oxo-dG in urine was developed based on aptamer-mediated quenching of amino-terminated oligo-(ethylene glycol)-capped gold nanoparticles (NH2-TEG-AuNPs) toward green emissive carbon dots (G-CDs). G-CDs were employed as fluorometric reporters. Upon addition of 8-oxo-dG, it formed a complex with an anti-8-oxo-dG aptamer, resulting in the quenching of fluorescence as NH2-TEG-AuNPs absorbed the emission from G-CDs. Initially, NH2-TEG-AuNPs suppressed the fluorescence intensity of G-CDs via the inner-filter effect (IFE). With the addition of the aptamers to a mixture of G-CDs and NH2-TEG-AuNPs, the electrostatic interactions between the aptamer and NH2-TEG-AuNPs resulted in the aggregation of NH2-TEG-AuNPs and the recovery of the fluorescence intensity of the quenched G-CDs. NH2-TEG-AuNPs dispersed due to the high affinity between the aptamer and 8-oxo-dG molecules, and the system demonstrated a fluorescence ″turn-off″ response of G-CDs. Thus, it was possible to determine the 8-oxo-dG concentration. A fluorescence calibration curve was constructed with two linear ranges: 100–2000 and 2000–10,000 nM. The limit of detection (LOD) for 8-oxo-dG was 15.89 nM. This approach was successfully applied to assess 8-oxo-dG in synthetic urine samples with mean recoveries ranging from 99 to 120% and relative standard deviations (RSDs) between 1.1 and 4.1%. The analytical performance was comparable to a commercially available enzyme-linked immunosorbent assay (ELISA) kit. This proposed fluorescent aptasensor for 8-oxo-dG detection in urine exhibited high selectivity and sensitivity over a broad concentration range against the target molecule and has the potential to be developed as a new platform for rapid screening of 8-oxo-dG. [ABSTRACT FROM AUTHOR]

Surface plasmon resonance (SPR) is a very sensitive measure of biomolecular interactions but is generally too expensive for routine analysis of clinical samples. Here we demonstrate the simplified formation of virus-detecting gold nanoparticle (AuNP) assemblies on glass using only aqueous buffers at room temperature. The AuNP assembled on silanized glass and displayed a distinctive absorbance peak due to the localized SPR (LSPR) response of the AuNPs. Next, assembly of a protein engineering scaffold was followed using LSPR and a sensitive neutron reflectometry approach, which measured the formation and structure of the biological layer on the spherical AuNP. Finally, the assembly and function of an artificial flu sensor layer consisting of an in vitro-selected single-chain antibody (scFv)-membrane protein fusion was followed using the LSPR response of AuNPs within glass capillaries. In vitro selection avoids the need for separate animal-derived antibodies and allows for the rapid production of low-cost sensor proteins. This work demonstrates a simple approach to forming oriented arrays of protein sensors on nanostructured surfaces that uses (i) an easily assembled AuNP silane layer, (ii) self-assembly of an oriented protein layer on AuNPs, and (iii) simple highly specific artificial receptor proteins. [ABSTRACT FROM AUTHOR]

Here, we report a switching method of singlet oxygen (1O2) generation based on the adsorption/desorption of porphyrins to gold nanoparticles driven by sulfide (thiol or disulfide) compounds. The generation of 1O2 by photosensitization is effectively suppressed by the gold nanoparticles and can be restored by a sulfide ligand exchange reaction. The on/off ratio of 1O2 quantum yield (ΦΔ) reached 7.4. By examining various incoming sulfide compounds, it was found that the ligand exchange reaction on the gold nanoparticle surface could be thermodynamically or kinetically controlled. The remaining gold nanoparticles in the system still suppress the generation of 1O2, which can be precipitated out simultaneously with porphyrin desorption by the proper polarity choice of the incoming sulfide to restore the 1O2 generation. [ABSTRACT FROM AUTHOR]

A novel voltammetric method was successfully applied for the determination of an anticholinergic drug, oxybutynin hydrochloride (OXB). The method is concerned with electrooxidation of the drug on the surface of pencil graphite electrode (PGE). In order to enhance the electrode sensitivity and peak current, the electrode was coated with gold nanoparticles (Au‐NPs) via electrochemical deposition using cyclic voltammetry from gold salt solution. The surface of Au‐NPs modified PGE has been characterized using scanning electron microscopy and X‐ray photoelectron spectroscopy. Various experimental variables were studied and optimized to enhance the sensor's response towards OXB. Quantitative determination of the drug was achieved in phosphate buffer pH 7.5 using differential pulse voltammetry by scanning the potential over range of 0.00 to 2.20 V with scan rate of 40 mV s−1. Validation of the method was achieved according to ICH guidelines. The method was found to be linear over concentration range (2.0×10−7–1.0×10−6 M). The suggested sensor was efficiently developed for the quantitative determination of OXB in pure form, pharmaceutical dosage form and spiked plasma samples. [ABSTRACT FROM AUTHOR]

Mycoplasma pneumoniae is a highly infectious bacterium and the major cause of pneumonia especially in school‐going children. Mycoplasma pneumoniae affects the respiratory tract, and 25% of patients experience health‐related problems. It is important to have a suitable method to detect M. pneumoniae, and gold nanoparticle (GNP)‐based colorimetric biosensing was used in this study to identify the specific target DNA for M. pneumoniae. The color of GNPs changes due to negatively charged GNPs in the presence of positively charged monovalent (Na+) ions from NaCl. This condition is reversed in the presence of a single‐stranded oligonucleotide, as it attracts GNPs but not in the presence of double‐stranded DNA. Single standard capture DNA was mixed with optimal target DNA that cannot be adsorbed by GNPs; under this condition, GNPs are not stabilized and aggregate at high ionic strength (from 100 mM). Without capture DNA, the GNPs that were stabilized by capture DNA (from 1 μM) became more stable under high ionic conditions and retaining their red color. The GNPs turned blue in the presence of target DNA at concentrations of 1 pM, and the GNPs retained a red color when there was no target in the solution. This method is useful for the simple, easy, and accurate identification of M. pneumoniae target DNA at higher discrimination and without involving sophisticated equipment, and this method provides a diagnostic for M. pneumoniae. [ABSTRACT FROM AUTHOR]

In this study, effective transport of small interfering RNAs (siRNAs) via hyaluronic acid (HA) receptor was carried out with biodegradable HA and low‐molecular weight polyethyleneimine (PEI)‐based transport systems. Gold nanoparticles (AuNPs) capable of giving photothermal response, and their conjugates with PEI and HA, were also added to the structure. Thus, a combination of gene silencing, photothermal therapy and chemotherapy, has been accomplished. The synthesized transport systems ranged in size, between 25 and 690 nm. When the particles were applied at a concentration of 100 μg mL−1 (except AuPEI NPs) in vitro, cell viability was above 50%. Applying radiation after the conjugate/siRNA complex (especially those containing AuNP) treatment, increased the cytotoxic effect (decrease in cell viability of 37%, 54%, 13%, and 15% for AuNP, AuPEI NP, AuPEI‐HA, and AuPEI‐HA‐DOX, respectively) on the MDA‐MB‐231 cell line. CXCR4 gene silencing via the synthesized complexes, especially AuPEI‐HA‐DOX/siRNA was more efficient in MDA‐MB‐231 cells (25‐fold decrease in gene expression) than in CAPAN‐1 cells. All these results demonstrated that the synthesized PEI‐HA and AuPEI‐HA‐DOX conjugates can be used as siRNA carriers that are particularly effective, especially in the treatment of breast cancer. [ABSTRACT FROM AUTHOR]

A novel colorimetric aptasensor based on charge effect-assisted silver enhancement was developed to detect ochratoxin A (OTA). To achieve this objective, gold nanoparticles (AuNPs), which can catalyze silver reduction and deposition, were used as the carrier of the aptamers tagged with a positively charged tetramethylrhodamine (TAMRA). Due to the mutual attraction of positive and negative charges, the TAMRA attracted and retained the silver lactate around the AuNPs. Thus, the chance of AuNP-catalyzed silver reduction was increased. The charge effect-assisted silver enhancement was verified by tagging different base pair length aptamers with TAMRA. Under optimized conditions, the as-prepared OTA aptasensor had a working range of 1 × 102–1 × 106 pg mL−1. The detection limit was as low as 28.18 pg mL−1. Moreover, the proposed aptasensor has been successfully applied to determine OTA in actual samples with satisfactory results. [ABSTRACT FROM AUTHOR]

In this study, systematic development of a portable sensor for the rapid detection of Escherichia coli (E. coli) and Exiguobacterium aurantiacum (E. aurantiacum) was reported. A conductive glass was utilized as a substrate and developed the electrode patterns on it. Trisodium citrate (TSC) and chitosan-stabilized gold nanoparticles (AuNPs) (CHI-AuNP-TSC) and chitosan-stabilized AuNPs (CHI-AuNP) were synthesized and utilized as a sensing interface. The morphology, crystallinity, optical properties, chemical structures, and surface properties of immobilized AuNPs on the sensing electrodes were investigated. The sensing performance of the fabricated sensor was evaluated by using an electrochemical method to observe the current changes in cyclic voltammetric responses. The CHI-AuNP-TSC electrode has higher sensitivity toward E. coli than CHI-AuNP with a limit of detection (LOD) of 1.07 CFU/mL. TSC in the AuNPs synthesis process played a vital role in the particle size, the interparticle spacing, the sensor's effective surface area, and the presence of CHI around AuNPs, thus enhancing the sensing performance. Moreover, post-analysis of the fabricated sensor surface exhibited the sensor stability and the interaction between bacteria and the sensor surface. The sensing results showed a promising potential for rapid detection using a portable sensor for various water and food-borne pathogenic diseases. [ABSTRACT FROM AUTHOR]

Currently, computed tomography and conventional X-ray radiography usually generate a micro-artifact around metal implants. This metal artifact frequently causes false positive or negative diagnoses of bone maturation or pathological peri-implantitis around implants. In an attempt to repair the artifacts, a highly specific nanoprobe, an osteogenic biomarker, and nano-Au-Pamidronate were designed to monitor the osteogenesis. In total, 12 Sprague Dawley rats were included in the study and could be chategorized in 3 groups: 4 rats in the X-ray and CT group, 4 rats in the NIRF group, and 4 rats in the sham group. A titanium alloy screw was implanted in the anterior hard palate. The X-ray, CT, and NIRF images were taken 28 days after implantation. The X-ray showed that the tissue surrounded the implant tightly; however, a gap of metal artifacts was noted around the interface between dental implants and palatal bone. Compared to the CT image, a fluorescence image was noted around the implant site in the NIRF group. Furthermore, the histological implant-bone tissue also exhibited a significant NIRF signal. In conclusion, this novel NIRF molecular imaging system precisely identifies the image loss caused by metal artifacts and can be applied to monitoring bone maturation around orthopedic implants. In addition, by observing the new bone formation, a new principle and timetable for an implant osseointegrated with bone can be established and a new type of implant fixture or surface treatment can be evaluated using this system. [ABSTRACT FROM AUTHOR]

This paper describes the size-selective preparation of gold nanoparticles stabilized on chitosan. The exchange of the matrix from the size-selectively prepared Au:PVPs(K-15) to chitosan (chit) proceeded by the mixing of Au:PVPs(K-15) and chitosan in an immiscible two-phasic solvent system to produce Au:chits, where 2-PrOH acts as a mediator. The size dependency of the catalytic activity of the thus-prepared Au:chits is investigated using a homocoupling reaction of phenylboronic acid under aerobic conditions to find that 2.3 nm-sized Au:chit exhibited the best catalytic activity, but the smaller-sized (1.4 nm) catalyst is better for the product selectivity. [ABSTRACT FROM AUTHOR]

In recent days, the number of cancer cases is escalating promptly around the world. In general, conventional ablation methods, encompassing comprehensive drawbacks, are employed to cure cancer. At present, photo thermal therapy (PTT) is showing great promise to the treatment of cancer. However, the effective implementation of this technology is utmost challenging as several parameters affect the tumor surroundings. In this work, the effects of different parameters on the performance of PTT have been thoroughly investigated by considering a realistic model of human tissue underneath the skin using a finite element solver, COMSOL Multiphysics. Two different conditions, with and without considering gold nanoparticles at tumor site, are investigated where a laser beam is used as a source of energy. Fluence rate, temperature distribution, and thermal damage are highlighted in this work. It is observed that by utilizing a miniature needle with integrated waveguide and gold nanoparticles, a tumor can be effectively eradicated along with assuaging the conventional drawbacks of PTT. This study would also be useful for designing operative PTT for different parts of human tissue. [ABSTRACT FROM AUTHOR]

A precise understanding of nano‐bio interactions in the sub‐nanometer regime is necessary for advancements in nanomedicine. However, this is currently hindered by the control of the nanoparticle size in the sub‐nanometer regime. Herein, we report a facile in situ Mn2+‐guided centrifugation strategy for the synthesis of large‐scale ultrasmall gold nanoparticles (AuNPs) with a precisely controlled size gradient at the sub‐nanometer regime. With the discovery that [Mn(OH)]+, especially metallic manganese (Mn0@[Mn(OH)]+) nanoparticles, could selectively interact with larger AuNPs through synergistic coordination and hydrogen bonding to form aggregates, we also realized the fast (<1 h) synthesis of water‐soluble atomically precise Au25 with high yields (>56 %). We further demonstrated that sub‐nanometer size differences (approximately 0.5 nm) significantly alter non‐specific phagocytosis of AuNPs in the reticuloendothelial system macrophages, elimination rate, and nanotoxicology. [ABSTRACT FROM AUTHOR]

This work deals with a numerical study of the different thermal processes in a gold nanoparticle heated with a femtosecond pulse laser and cooled in different biological tissues, such as healthy human prostate, blood, fat, tumor prostate, skin and protein myoglobin. A 40 nm diameter gold nanoparticle is heated using a femtosecond pulse laser with a duration of 85 fs and a fluence of 1.4 J/m2. A two-temperature model is used to describe the dynamics of the exchange of energy between the electron gas and the phononic lattice in addition to Fourier's law and the relationship between the thermal conductivity of the external medium and the temperature. The temperature of the external medium near the nanoparticle surface was computed, and the effect of the laser energy was reported. [ABSTRACT FROM AUTHOR]

In this work, two human epidermal growth factor receptors, HER-1 and HER-2, were selected as biomarkers to enable the detection of breast cancer. Therefore, two biosensors were developed using gold sensor chips coupled with amperometric detection of the enzyme label horse radish peroxidase (HRP). The biosensors/immunosensors relied on indirect sandwich enzyme-linked immunosorbent assays with monoclonal antibodies (Ab) against HER-1 and HER-2 attached to the sensors to capture the biomarkers. Detection polyclonal antibodies followed by secondary anti-rabbit (for HER-1) and anti-goat (for HER-2) IgG antibody-HRP were then applied for signal generation. In buffer, the developed sensors showed limits of detections (LOD) of 1.06 ng mL−1 and 0.95 ng mL−1 and limits of quantification (LOQ) of 2.1 ng mL−1 and 1.5 ng mL−1 for HER-1 and HER-2, respectively. In 100% (undiluted) serum, LODs of 1.2 ng mL−1 and 1.47 ng mL−1 and LOQs of 1.5 ng mL−1 and 2.1 ng mL−1 were obtained for HER-1 and HER-2, respectively. Such limits of detections are within the serum clinical range for the two biomarkers. Furthermore, gold nanoparticles (AuNP) labelled with secondary anti-rabbit and anti-goat IgG antibody-HRP were then used to enhance the assay signal and increase the sensitivity. In buffers, LODs of 30 pg mL−1 were seen for both sensors and LOQs of 98 pg mL−1 and 35 pg mL−1 were recorded for HER-1 and HER-2, respectively. For HER-2 the AuNPs biosensor was also tested in 100% serum obtaining a LOD of 50 pg mL−1 and a LOQ of 80 pg mL−1. The HER-2 AuNP electrochemical immunosensor showed high specificity with very low cross-reactivity to HER-1. These findings demonstrate that the two developed sensors can enable early detection as well as monitoring of disease progression with a beneficial impact on patient survival and clinical outcomes. [ABSTRACT FROM AUTHOR]

Tuberculosis (TB) has been a devastating human illness for thousands of years. According to the WHO, around 10.4 million new cases of tuberculosis are identified every year, with 1.8 million deaths. To reduce these statistics and the mortality rate, an early and accurate TB diagnosis is essential. This study offers a highly sensitive and selective electrochemical biosensor for Mycobacterium tuberculosis (MTB) detection based on a ternary nanocomposite of reduced graphene oxide, polydopamine, and gold nanoparticles (rGO-PDA-AuNP). Avidin-biotin coupling was used to bind the MTB probe DNA onto the rGO-PDA-AuNP modified glassy carbon electrode (ssDNA/avidin/rGO-PDA-AuNP). UV-Visible, Raman, XRD, and TEM were used to evaluate the structural and morphological characteristics of rGO-PDA-AuNP. Furthermore, DNA immobilization is validated using FESEM and FT-IR techniques. The modified electrodes were electrochemically analyzed using cyclic voltammetry (CV) and linear sweep voltammetry (LSV), and the results indicate that the produced electrode can detect target DNA up to 0.1 × 10−7 mM with 2.12 × 10−3 mA µM−1 sensitivity and a response time of 5 s. The constructed genosensor displayed high sensitivity and stability, and it also provides a unique strategy for diagnosing MTB at an early stage. Furthermore, our rGO-PDA-AuNP/GCE-based electrochemical platform has broad potential for creating biosensor systems for detecting various infectious pathogens and therapeutically significant biomarkers. [ABSTRACT FROM AUTHOR]

Purpose: Radiotherapy is one of the most important therapeutic options used to treat cancers.Radiation effects can be improved using nanoparticles and chemotherapeutic drugs asradiosensitizing agents. The aim of the present study was to evaluate the effects of folic acidconjugatedgold nanoparticles (GNP-F) in combination with doxorubicin (DOX) and x-Rayirradiation in colorectal cancer (CRC) cell line (HT-29).Methods: The cell viability assay (WST-1) was performed to study the cytotoxic effects ofdifferent concentrations of DOX and GNP-F after 24 and 48 hours treatments. Then, the effectsof the GNP-F, X-Ray irradiation, and DOX drug in single and combined treatments wereexamined after 24 and 48 hours treatment with effective doses. Likewise, the caspase 3 geneexpression ratio and the caspase 3 activity were assessed after 48 h treatment. Moreover, themalondialdehyde (MDA) level was determined in treated and untreated cells.Results: When GNP-F (at a concentration of 70 μM) was combined with X-ray irradiation (2Gy) and DOX drug, induced more cytotoxic effects compared to the control group. The resultsof cell viability assay showed that GNP-F + X-Ray in combination with a low concentrationof DOX (0.25 × IC50) enhanced the cytotoxic effects of cells compared to related singletreatments. Caspase 3 gene expression ratio and caspase 3 activity increased in double andtriple combination treatments in comparison with the single groups. Moreover, the MDA levelincreased in triple combination compared to the single treatments.Conclusion: Our findings confirmed the potential anti-cancer effects of the GNP-F and DOX incombination with X-Ray irradiation in CRC cells.

Objective(s): Photochemical internalization (PCI) is an important type of photodynamic therapy for delivering macromolecules into the cytosol by the endocytosis process. In this study, 6-mercapto-1-hexanol (MH) was used to functionalize the gold nanostructure as a primer for surface modification to improve conjugation of multi-agents such as protoporphyrin IX (Pp-IX) and folic acid with gold nanoparticles (PpIX/FA-MH-AuNP) to facilitate the photochemical internalization.Materials and Methods: After surface modification of AuNPs with MH, PpIX and FA are bonded to the surface of the MH-AuNPs through the coupling reaction to produce the desired conjugated AuNPs. In the next step, the synthesized nanostructures were characterized by different methods. Finally, after selecting specific concentrations, light treatments were applied and cell survival was measured based on MTT analysis. Also, in order to better study the morphology of the cells, they were stained by the Giemsa method. The SPSS 16 software was used for data analysisResults: By surface modification of the nanostructure with MH and then conjugation of FA to it, the incubation time of the drug in PpIX/FA-MH-AuNP was reduced from 3 hr to 30 min. Also, at each light dose, cell death in the presence of PpIX/FA-MH-AuNP was significantly reduced compared with unconjugated conditions (P

Abstract Background Radionuclide therapy (RNT) has become a very important treatment modality for cancer nowadays. Comparing with other cancer treatment options, sufficient efficacy could be achieved in RNT with lower toxicity. β− emitters are frequently used in RNT due to the long tissue penetration depth of the β− particles. The dysprosium-166/holmium-166 (166Dy/166Ho) in vivo generator shows great potential for treating large malignancies due to the long half-life time of the mother nuclide 166Dy and the emission of high energy β− from the daughter nuclide 166Ho. However, the internal conversion occurring after β− decay from 166Dy to 166Ho could cause the release of about 72% of 166Ho when 166Dy is bound to conventional chelators. The aim of this study is to develop a nanoparticle based carrier for 166Dy/166Ho in vivo generator such that the loss of the daughter nuclide 166Ho induced by internal conversion is prevented. To achieve this goal, we radiolabelled platinum-gold bimetallic nanoparticles (PtAuNPs) and core–shell structured gold nanoparticles (AuNPs) with 166Dy and studied the retention of both 166Dy and 166Ho under various conditions. Results The 166Dy was co-reduced with gold and platinum precursor to form the 166DyAu@AuNPs and 166DyPtAuNPs. The 166Dy radiolabelling efficiency was determined to be 60% and 70% for the two types of nanoparticles respectively. The retention of 166Dy and 166Ho were tested in MiliQ water or 2.5 mM DTPA for a period of 72 h. In both cases, more than 90% of both 166Dy and 166Ho was retained. The results show that the incorporation of 166Dy in AuNPs can prevent the escape of 166Ho released due to internal conversion. Conclusion We developed a chelator-free radiolabelling method for 166Dy with good radiolabelling efficiency and very high stability and retention of the daughter nuclide 166Ho. The results from this study indicate that to avoid the loss of the daughter radionuclides by internal conversion, carriers composed of electron-rich materials should be used.

Active targeting strategy in chemotherapy drug delivery aims to improve the therapeutic outcomes and minimize the side effects of chemotherapeutics. This review discusses utilizing ligands attached to gold nanoparticles (AuNPs) along with several specific ligands attached to AuNPs for active targeting in chemotherapy drug delivery. Antibodies, peptides, vitamins, DNA, polysaccharides, aptamers, and hormones showed active-targeting abilities as ligands attached to AuNPs. Active-targeting AuNPs enhanced cellular uptake and cytotoxicity in a specific cancer cell in vitro while reducing tumor growth in vivo by improving the photothermal, photodynamic and chemotherapy effects. Active-targeting ligands increased the internalization of AuNPs loaded onto the specific tumor site and minimized the accumulation in the normal site. AuNPs with active-targeting ligands such as antibodies, peptides, vitamins, DNA polysaccharides, aptamers, and hormones can improve the therapeutic outcomes of chemotherapeutics and can attenuate the toxicity effect in normal cells. For further research and development, researchers should be addressing AuNP characterization, drug–ligand disposition, active-targeting AuNP quantification, and target-AuNPs pertinence concerning the desired therapeutic outcomes.

Glioblastoma (GB) is the most malignant subtype of brain cancer derived from astrocytes in the brain. Radiotherapy is one of the standard treatments for GB patients, but its effectiveness is often limited by the radioresistance of aggressive GB cells. Higher dose of radiation needs to be applied to GB patients to eliminate these stubborn cells, but this also means more side effects on the adjacent healthy cells because the radiation beam could indistinguishably harm all cells exposed to it. In order to address this problem, various strategies have been studied to enhance the radiosensitivity among the radioresistant cell populations for targeted eradication of GB without harming other surrounding healthy cells. One of the promising strategies for radiosensitization is to use gold nanoparticles (AuNPs) which can enhance photoelectric effects within the radioresistant cells for higher killing efficiency even at low doses of radiation. Nonetheless, there is no evidence showing the capability of these nanoparticles to travel to brain tumor cells, therefore, the application of this nanotechnology is very much dependent on the development of a suitable carrier to deliver the AuNPs to the GB tumor sites specifically. In this review article, we discussed the potentials of neural stem cells (NSCs) as biological carriers to carry AuNPs to targeted GB tumor sites and provided new insights into the potential of NSC-based targeted delivery system for GB treatment. The information reported here may pave a new direction for clinical transformation of next-generation nanoparticle-assisted radiotherapy to optimize the efficacy of radiotherapy for GB treatment.

• Citrate-, glutathione-, and ascorbic acid-capped AuNPs were synthesized. • The synthesized AuNPs were tested with varying experimental conditions. • Colloidal stability of AuNPs were correlated with tolerance levels of AuNPs. • Glutathione capped AuNPs were the most stable AuNPs. In recent times, gold nanoparticles (AuNPs) have been the centre of attraction for the researchers working in diverse technological fields, e.g., biomedical to material science. The colloidal stability of the AuNPs is one of the crucial factors to utilize them efficiently for any practical application. By considering the importance of AuNPs stability, this work thoroughly investigated the stability of AuNPs colloidal solutions under a range of saline, temperature, and pH conditions. Herein, three differentially capped AuNPs, namely citrate (AuNPs-I), glutathione (AuNPs-II), and ascorbic acid-capped AuNPs (AuNPs-III) were prepared and carefully examined for their colloidal stability under varying stress conditions. Notably, we experimentally identified specific conditions (by monitoring LSPR peak and AuNPs solution color) up to which AuNPs are stable and usable for diverse applications. Out of the tested AuNPs, AuNPs-II are the most stable in terms of heat tolerance (up to 70 °C), exposure of high salt conditions (up to 1600 mM), and a wide pH range (3–11), followed by AuNP-I and III. [Display omitted] [ABSTRACT FROM AUTHOR]

Graded-thickness gold layers were deposited on fused silica by combinatorial magnetron sputtering and annealing to form nanoparticles with a laterally changing structure. The optical properties and sensing characteristics were determined as a function of the amount of sputtered material by scanning optical spectroscopies. The formation and sensing performance of Au nanoparticles were modeled and interpreted by finite element electromagnetic calculations. The most sensitive regions for the optical detection of ethanol, water, and Raman reporter molecules on the heat-treated surfaces were determined as a function of the deposited amount of Au. For all three analytes applied, we observed the best sensing performance for an effective deposited gold thickness of 2–3 nm. These results can be interpreted by considering the graded gold film's actual geometry and near-field optical properties. • Au nanoparticles with continuously varying properties created by controlled-gradient magnetron sputtering and annealing. • Best gas sensing characteristics for adsorbed ethanol and water molecules for equivalent deposition thicknesses of 2–3 nm. • Covalently bonded molecules most sensitively detected at highest plasmon peak region for equivalent thicknesses of 7 nm. • Raman signal of covalently bonded molecules highest for equivalent thicknesses of 1–3 nm. • Optical response explained by hemispherical nanoparticle shape with increasing interparticle gaps in the region of interest. [ABSTRACT FROM AUTHOR]

[Display omitted] • Green synthesis of AuNPs using ethanolic extract of Madhuca indica flower. • Characterization of MI-AuNPs revealed unique morphological features. • MI-AuNPs exhibited significant cytotoxicity against HNSCC model. Complete eradication of aggressive head and neck squamous cell carcinoma (HNSCC) still remains a major challenging problem due to numerous resistance properties of cancer stem cells (CSC) which is crucially responsible for tumor recurrence and metastasis. This challenge causes a high demand for the emergence of novel targeted treatment modalities for improved therapeutic efficacies. Phytochemicals derived from plants proves to be a wide reservoir of important drug candidates which have the potential to impede multiple aspects of malignant growth and progression. In the present study, we aimed to synthesize gold nanoparticles in a rapid and cost-effective manner by utilizing Madhuca indica flower extract and to evaluate its anticancer efficacy on head and neck cancer model via targeting cancer stemness and EMT. The phytochemicals present in the Madhuca indica flower extract acted as an effective reducing agent helping in the green synthesis of gold nanoparticles. The generated AuNPs were characterized by UV–Vis spectroscopy, XRD, FTIR, TEM, FE-SEM, DLS, EDX. Anti cancer potential of synthesized AuNPs were evaluated by in vitro and ex vivo HNSCC model. In vivo toxicity was assessed in Swiss albino mice model. The gold nanoparticles were characterized using UV–Vis spectroscopy which revealed unique wavelength maxima at 550 nm and its crystalline nature was confirmed by XRD. AuNPs were observed to be spherical in shape with the mean diameter of 20.34 ± 4.36 nm and zeta potential of nearly −50 mV. The FTIR spectral shift indicated the incorporation of various functional groups. MI-AuNP depicted strong anticancer attributes against HNSCC cell lines SCC154 and FaDu through significant inhibition of cancer stemness and EMT as evident from decreased tumor sphere forming efficiency and CD44+/CD24- subpopulation along with dose dependent downregulated expression of relevant CSC markers and EMT markers both in vitro and ex vivo HNSCC model. Additionally, no evidence of in vivo toxicity has been observed with MI-AuNP administration. In conclusion, this study reported for the first time that the MI-AuNP synthesized by novel green chemistry can efficiently prevent the self-renewal capability of HNSCC by targeting Cancer stemness. The scientific significance of this study lies in the fact that MI-AuNP might be a novel and potential therapeutic candidate against aggressive and metastatic HNSCC. The findings in this study unravels the way for developing a novel therapeutic candidate against aggressive and metastatic HNSCC with a much higher prognostic potential and significantly reduced off target toxicity. [ABSTRACT FROM AUTHOR]

[Display omitted] • The glycyrrhizic acid was introduced as the exfoliating biomolecule. • The MoSe 2 nanosheets were exfoliated using biocompatible materials in aqueous. • The AuNPs deposited on the exfoliated MoSe 2 nanosheet by spontaneous reduction. • To enhance the cancer-targeting properties of FAM, folic acid was introduced. • These surface-modified nanomaterials can effectively induce apoptosis of TNBC. Breast cancer, particularly triple-negative breast cancer (TNBC), is the most impactful cancer affecting women, necessitating continuous evaluation of enhanced treatment methods. In this study, we synthesized a folic acid-modified gold nanoparticle-MoSe 2 composite (FAM) by liquid exfoliation using glycyrrhizic acid (GA), spontaneous reduction of AuNP, and linkage between folic acid and AuNP using EDC/NHS coupling. With the assistance of GA, MoSe 2 nanosheets can be easily exfoliated in aqueous solutions and exhibit biocompatibility. In addition, the gold nanoparticle deposition on the nanosheet was spontaneously induced due to the electron transfer property of MoSe 2. Folic acid was used as a targeting molecule because triple-negative breast cancer (TNBC) lacks the common breast cancer markers. We investigated the effectiveness of photothermal therapy using FAM, which enhances light-heat transfer through the synergistic effect of gold and GA-exfoliated MoSe 2 (GM). The nanomaterials exhibited improved photothermal conversion efficiency of 62.2 %, high thermal stability, and increased cellular uptake ratio. Subsequently, when the FAM reached the tumor microenvironment, the materials successfully entered the cells through folate receptor-mediated endocytosis and generated heat to kill cells under an 808 nm laser (0.8 W cm−2) by apoptosis. The biocompatibility and photothermic activity of FAM were determined in vitro by a tetrazolium salt assay, live/dead cell staining, cellular uptake ratio, and flow cytometry with human TNBC cells (MDA-MB-231). In summary, the FAM showed a more advanced therapeutic effect than GM in all outcomes. Our findings indicate that FAM has the potential to be used as a biomaterial for anticancer therapy. [ABSTRACT FROM AUTHOR]

AuNPs/ZnONRs heterojunctions were grown on SSWS and stimulated via UV irradiation. Synergistic effect of AuNPs/ZnONRs heterojunctions and UV significantly improve electro-catalytic capacity of glucose sensor. [Display omitted] • A flexible glucose sensor was fabricated with AuNPs/ZnONRs heterojunctions grown on SSWS. • The heterojunctions were stimulated via UV irradiation for enhanced glucose sensing performance. • Synergistic effect of the heterojunctions and UV irradiation remarkably enhances catalytic capacity of sensor. • The sensitivity was raised by ∼9.5 times and the detection limit was diminished by ∼10 times. • The glucose sensor can reliably analyze glucose contents in sweat and fruit juices. Continuous high glucose levels in blood could cause heart disease, liver dysfunction, kidney failure, and blindness to diabetics. To detect glucose levels non-invasively and precisely, it is urgent to construct flexible and sensitive sensors to monitor glucose levels in time. Herein, a flexible non-enzymatic electrochemical glucose sensor was fabricated with gold nanoparticles/ZnO nanorods (AuNPs/ZnONRs) heterojunctions modified on stainless steel wire sieve (SSWS), and further it was stimulated under UV irradiation for enhanced electro-catalytic capacity. The AuNPs not only as excellent electron carrier facilitate electron immigration at the solid/liquid interface, but also as favorable catalyst oxidize glucose. More importantly, under the synergistic effect of the AuNPs/ZnONRs heterojunctions and the UV irradiation, the AuNPs efficiently separate UV-generated electron/hole pairs within the ZnONRs and more holes react with H 2 O to produce sufficient hydroxyl, which as oxidants oxidize glucose. Consequently, the sensitivity of the AuNPs/ZnONRs/SSWS glucose sensor significantly raises from 36.4 μA·mM−1·cm−2 to 344.3 μA·mM−1·cm−2 over a wide linear range of 14.0 mM, and the low detection limit diminishes from 2.1 μM to 0.21 μM. Additionally, the sensor displays desirable selectivity, bending capability, and stability, and it could also reliably analyze glucose contents in sweat and fruit juices. This work demonstrates a novel and effective method for improved electro-catalytic capacity of non-enzymatic electrochemical glucose sensors using the synergistic effect of the AuNPs/ZnONRs heterojunctions and UV irradiation, and it could be used to enhance the sensing performance of other electrochemical biosensors. [ABSTRACT FROM AUTHOR]

A well-performing electrochemical immunosensor was prepared for detecting the tumor biomarker of carcinoembryonic antigen (CEA) by modifying a glassy carbon electrode (GCE) with a nanocomposite comprising gold nanoparticles (AuNPs), coiled carbon nanotubes (CCNTs), and chitosan (Chi) along with bovine serum proteins and CEA antibody. Various electrochemical methods such as cyclic voltammetry (CV) and square wave voltammetry (WV) were utilized for characterization. The substantial surface area and strong conductivity of AuNPs and CCNTs, and easy film-forming nature of Chi, enhanced the effective surface area and conductivity of the CEA-immunosensors to nearly twice that of the GCE before modification. Under the best experimental conditions, the CEA immunosensor showed good reproducibility with a selective linear detection range of 1 pg mL−1–400 ng mL−1 and a detection limit as low as 1 pg mL−1. The decrease in current exhibited a strong linear relationship with the logarithmic values of CEA concentration, boasting a correlation coefficient of 0.99379. The developed CEA immunosensor had good performance and the potential for practical application to real samples with good selectivity and immunity to other antigens in the presence of serum.Graphical abstract: A well-performing electrochemical immunosensor was prepared for detecting the tumor biomarker of carcinoembryonic antigen (CEA) by modifying a glassy carbon electrode (GCE) with a nanocomposite comprising gold nanoparticles (AuNPs), coiled carbon nanotubes (CCNTs), and chitosan (Chi) along with bovine serum proteins and CEA antibody. Various electrochemical methods such as cyclic voltammetry (CV) and square wave voltammetry (WV) were utilized for characterization. The substantial surface area and strong conductivity of AuNPs and CCNTs, and easy film-forming nature of Chi, enhanced the effective surface area and conductivity of the CEA-immunosensors to nearly twice that of the GCE before modification. Under the best experimental conditions, the CEA immunosensor showed good reproducibility with a selective linear detection range of 1 pg mL−1–400 ng mL−1 and a detection limit as low as 1 pg mL−1. The decrease in current exhibited a strong linear relationship with the logarithmic values of CEA concentration, boasting a correlation coefficient of 0.99379. The developed CEA immunosensor had good performance and the potential for practical application to real samples with good selectivity and immunity to other antigens in the presence of serum. [ABSTRACT FROM AUTHOR]

A sensitive dual immunochromatographic test strip (dual-ICTS) was developed to detect malachite green (MG) and its metabolite, leucomalachite green (LMG), using two types of gold nanoparticles: round-shaped (red) and star-shaped (blue). The detection limits were determined to be 0.221 μg L−1 for MG and 0.214 μg L−1 for LMG, respectively. The dual-ICTS provided a cut-off value of 1.8 μg L−1 for MG and LMG detection. The dual-ICTS successfully detected MG and LMG in food samples, with recovery rates ranging from 86 % to 116 %. The dual-ICTS was evaluated by correlation analysis between the proposed assay and the well-established enzyme-linked immunosorbent assay in the MG and LMG detection. This is the first report on the development of the ICTS that can detect both MG and LMG at the same time within only 5 min, making it a sensitive and rapid tool for on-site detection. [Display omitted] • Two colored gold nanoparticles were applied as dual - color labels in ICTS. • A novel dual-ICTS was fabricated for simultaneous detection of MG and LMG. • The dual-ICTS provided a cut-off value of 1.8 μg L−1 for MG and LMG detection. • ICTS is a rapid, for on-site simultaneous detection for MG and LMG within 5 min. [ABSTRACT FROM AUTHOR]

The Mucin1 (MUC1) protein, involved in cytoprotective and signaling pathways, is abnormally elevated in various cancers, making it a key cancer indicator. Exosomes, which reflect the status of their originating cells, offer potential for cancer diagnosis. Thus, developing a method to detect MUC1-positive exosomes is crucial for the early diagnosis of certain cancers. In this study, we developed a highly sensitive, specific, and simple UV–visible signal amplification method to detect MUC1-positive exosomes using terminal deoxynucleotidyl transferase (TdT). Initially, exosomes were captured on magnetic beads using a CD63 aptamer(apt). The Primer-AuNPs-MUC1 apt complex which we synthesized by low pH loading method was then attached MUC1 proteins on the surface of the exosomes to create a sandwich structure. TdT catalyzed the extension of Biotin-dATP at the 3′ end of the primer, introducing multiple biotin sites into the sandwich structure. These sites subsequently bound multiple streptavidin-horseradish peroxidase (streptavidin-HRP), which catalyzed the oxidative color change of the substrate, which can be detected by colorimetric method. This method can detect A549 exosomes in the range of 1.4E+6 to 4.2E+8 particles/mL and shows high specificity for cell lines with different MUC1 expression. Additionally, it successfully distinguished cholangiocarcinoma (CCA) patients (n=11) from healthy individuals (n=7) in clinical serum assays, demonstrating good performance in real sample detection. • Developed an exosome detection system based on the dual targets of MUC1 and CD63. • Utilizing aptamers to bind targets, stable and cheap. • The method is based on TdT to realize efficient and simple signal amplification. • The method demonstrates the potential of exosome-based cancer diagnosis. [ABSTRACT FROM AUTHOR]

The functionalization of gold nanoparticle (AuNP) is the key procedure for the biochemical and biomedical application. The conventional salt-aging method requires the stepwise additions of NaCl and excessive thiolated DNA, mainly due to the poor tolerance of the DNA/AuNP mixture toward NaCl. Herein, we found that NaF is capable of improving the stability for the modification of AuNP with different bases of DNA sequences (poly A/T/C/G), and allows for adding up with a high concentration of 200 mM at one time, which greatly reduces the total modification time to 0.5–1 h. Intriguingly, the introduction of NaBr effectively increases the DNA loading capacity. Besides the advantages of NaF and NaBr , the modification performance is improved via the introduction of the oligo A/T spacer for the G -rich DNA sequences. Furthermore, this method shows the superiority to another two methods (pH 3-based and salt-aging) in terms of the loading capacity or sequence components. [Display omitted] [ABSTRACT FROM AUTHOR]