Search

The purpose of this study was to compare and characterize the theoretical properties and interaction mechanisms of zein and isoquercetin (ISO) from experimental and theoretical perspectives. Zein nanoparticles with different ISO concentrations (ZINPs) were prepared by the antisolvent precipitation method. The experimental results indicated all particles appeared spherical. When the mass ratio of zein to ISO was 10:1, the encapsulation efficiency of ZINPs reached 88.19 % with an average diameter of 126.67 nm. The multispectral method and molecular docking results confirmed that hydrogen bonding and van der Waals force played a dominant role for the binding of ISO to zein, and the primary fluorescence quenching mechanism for zein by ISO was static quenching. Furthermore, ZINPs had greater solubility and antioxidant activity, as well as inhibited the release of ISO during simulated gastrointestinal digestion processes. This research contributes to the understanding of the non-covalent binding mechanism between zein and ISO, providing a theoretical basis for the construction of ISO active carriers., Competing Interests: Declaration of competing interest The authors declare no competing financial interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Bone defects are often difficult to treat due to their complexity and specificity, and therefore pose a serious threat to human life and health. Currently, the clinical treatment of bone defects is mainly surgical. However, this treatment is often more harmful to patients and there is a potential risk of rejection and infection. Hydrogels have a unique three-dimensional structure that can accommodate a variety of materials, including particles, polymers and small molecules, making them ideal for treating bone defects. Therefore, emerging composite hydrogels are considered one of the most promising candidates for the treatment of bone defects. This review describes the use of different types of composite hydrogel in the treatment of bone defects. We present the basic concepts of hydrogels, different preparation techniques (including chemical and physical crosslinking), and the clinical requirements for hydrogels used to treat bone defects. In addition, a review of numerous promising designs of different types of hydrogel doped with different materials ( e.g. , nanoparticles, polymers, carbon materials, drugs, and active factors) is also highlighted. Finally, the current challenges and prospects of composite hydrogels for the treatment of bone defects are presented. This review will stimulate research efforts in this field and promote the application of new methods and innovative ideas in the clinical field of composite hydrogels.

This study develops hemp seed globulin (GLB)-alginate (ALG) nanoparticles (GANPs) for Cannabisin A (CA) stabilization under environmental stress and during pepsin digestion. The optimal GLB: ALG mass ratio of 1: 1.5 was determined for GANPs formation at pH 3.5, resulting in a high yield of 95.13 ± 0.91 %, a ζ-potential of -35.73 ± 1.04 mV, a hydrodynamic diameter of 470.67 ± 11.36 nm, and a PDI of 0.298 ± 0.016. GANPs were employed to encapsulate CA, achieving a high loading capacity of 13.48 ± 0.04 μg mg -1 . FTIR analysis demonstrated that the formation of CA-GLB-ALG nanoparticles (CGANPs) involves electrostatic interactions, hydrogen bonding, and hydrophobic interactions. XRD and DSC analyses revealed that CA is amorphous within the CGANPs. CGANPs demonstrated remarkable dispersion stability as well as resistance to high ionic strength and high-temperature treatments, indicating their potential as efficient hydrophobic drug-delivery vehicles. When compared to free CA, CA coated within CGANPs displayed greater DPPH/ABTS scavenging activity. Furthermore, the ALG-shelled nanoparticles protected GLB from pepsin digestion and slowed the release of CA throughout the release process, extending their stay on the intestinal wall mucosa. These findings imply that CGANPs is an ideal delivery vehicle for CA as they may expand the application of CA in food items., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)

Nanoparticles can promote the accumulation of drugs in tumors. However, they find limited clinical applications because they cannot easily penetrate the stroma of cancer tissues, and it is difficult to control drug release. We developed a multiresponse multistage drug-delivery nanogel with improved tumor permeability and responsiveness to the tumor microenvironment for the controlled delivery of anticancer agents. For this purpose, ∼100 nm multistage drug delivery nanogels with pH, redox, near-infrared stimulation, and enzyme responsiveness were grown in situ using 20 nm gold nanoparticles (AuNPs) via an emulsion-aiding crosslinking technique with cysteine crosslinker. An alginate cysteine AuNP (ACA) nanocarrier can efficiently load the cationic drug doxorubicin (DOX) to produce a multistage drug delivery nanocarrier (DOX@ACA). DOX@ACA can maintain the slow release of DOX and reduce its toxicity. In cancer tissues, the high pH and reductase microenvironment combined with the in vitro delivery of alginate and near-infrared light drove drug release. The developed nanoparticles effectively inhibited cancer cells, and in vivo evaluations showed that they effectively enhanced antitumor activity while having negligible in vivo toxicity to major organs.

Exploring the advanced techniques for protein detection facilitates cell fate investigation. However, it remains challenging to quantify and visualize the protein with one single probe. Here, a luminescent approach to detect hepatic cell fate marker albumin in vitro and living cell labeling with upconversion nanoparticles (UCNPs), which are conjugated with antibody (Ab) and rose bengal hexanoic acid (RBHA) is reported. To guarantee the detection quality and accuracy, an "OFF-ON" strategy is adopted: in the presence of albumin, the luminescence of nanoparticles remains suppressed owing to energy transfer to the quencher. Upon albumin binding to the antibody, the luminescence is recovered under near-infrared light. In various bio-samples, the UCNPs-Ab-RBHA (UCAR) nanoprobe can sense albumin with a broad detection range (5-315 ng mL -1 ). When applied to liver ductal organoid culture medium, the UCAR can monitor hepatocyte differentiation in real time by sensing the secreted albumin. Further, UCAR enables live imaging of cellular albumin in cells, organoids, and tissues. In a CCl 4 -induced liver injury model, UCAR detects reduced albumin in liver tissue and serum. Thus, a biocompatible nanoprobe for both quantification and imaging of protein in complex biological environment with superior stability and high sensitivity is provided., (© 2022 The Authors. Advanced Science published by Wiley-VCH GmbH.)

Lead sulfide nanoparticle (nano-PbS) released into environment can cause hazards to human or ecosystem. Nano-PbS potentially undergoes oxidation in the environment, but oxidation mechanism is not understood yet. Herein, oxidation kinetics and products of nano-PbS by ozone (O 3 ), hydrogen peroxide (H 2 O 2 ) and hydroxyl radical (HO·) in the atmosphere or natural water were investigated. Results show that oxidation process of nano-PbS can be divided into three stages, producing sulfate, ions and oxides of lead in sequence. O 3 or HO·leads to faster release of ionic lead from nano-PbS in the initial stage than H 2 O 2 , but causes significant decrease of ionic lead by transforming divalent lead to tetravalent lead oxides in the second or third stage. Toxicity determined taking Chlorella Vulgaris as an example follows an order of PbO 2 < Pb 3 O 4 < nano-PbS < PbO < PbSO 4 . Toxicity of lead particles is mainly determined by sizes influencing cellular uptake and solubility product constant (K sp ) related with dissolution of lead in cells. The results indicate that the toxicity of nano-PbS increases in an initial oxidation stage and decreases in further oxidation stages. This study provides new insights into environmental behavior of nano-PbS and mechanism understandings for assessing ecological risks of nano-PbS., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Ag + and SCN - play extremely important roles in the fields of the physiology and environment. In this work, on the basis of phenanthro[9,10-d]imidazole derivative (DIPIP) which can exhibit the aggregation-induced emission (AIE) properties in aqueous solution, we achieved a sequential on-off-on switch for Ag + and SCN - with high selectivity and sensitivity. A remarkable fluorescence quenching effect of Ag + on the probe DIPIP was observed with 1:2 stoichiometry, Subsequently, the fluorescence intensity of in situ generated DIPIP-Ag + ensemble was easily switched on after the interaction between Ag + and SCN - , which was attributed to the stronger affinity of SCN - to capture Ag + . In particular, the extreme limits of detection (LOD) for Ag + and SCN - in standard solutions were as low as to be 74.5 nM and 7.8 nM, respectively. Furthermore, the probe DIPIP and the DIPIP-Ag + ensemble could be used to detect Ag + in the real water and SCN - in smoker saliva samples, respectively. In addition, the sequential "on-off-on" fluorescence mode of DIPIP to Ag + and SCN - were also successfully applied in living HeLa cells., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Rare-earth-doped upconversion nanoparticles (UCNPs) behaved advantages such as non-autofluorescence, environment-friendly synthetic route, low cost and simple detection procedures. In addition, the UCNPs show unique upconvering optical property of converting low-energy infrared photons to high-energy visible ones. Here in our work, water and ethylene glycol at the ratio of 1/1 (v/v) were chosen as solvent. Polyethyleneimine (PEI) was chosen as surface additives to synthesize the NaYF 4 :Yb 3+ , Tm 3+ UCNPs by one-pot route at 200°C. The as-prepared UCNPs exhibited a strong emission at 473nm under the continuous excitation at 980nm. Dopamine (DA), one of the important catecholamine neurotransmitters, shows a crucial role to regulate the memory and attention in brain, renal and hormonal systems. DA molecules could be gently oxidized to quinone structure (ox-DA) in air-containing buffer solution under alkaline condition. In this study, a label-free luminescent probe based on the luminescence energy transfer (LET) between the NaYF 4 :Yb 3+ , Tm 3+ UCNPs and ox-DA was developed for highly sensitive and selective detection of DA. The luminescent response ratios (I 0 /I) increased linearly with the concentration of DA increasing in the ranges of 0.25 - 150µM. The relative standard deviation (RSD) for 11 replicate detections of 25µM DA was 0.48%, and the limit of detection was 124nM. The developed method was applied for detection of DA in biological fluids with the quantitative spike recoveries from 94.8% to 103.6%., (Copyright © 2017 Elsevier B.V. All rights reserved.)

TiO(2) and Mn-doped TiO(2) (1%, 3% and 5%) nanoparticles (NPs) were synthesized by a sol-hydrothermal method for surface-enhanced Raman spectroscopy study. When using the 4-mercaptobenzoic acid (4-MBA) as the probing molecule, optimum SERS signals were observed on the Mn-TiO(2) (3%) samples. On the 3% Mn doped TiO(2) substrate, 4-MBA molecules exhibit a higher SERS intensity by a factor of six as compared with the native enhancement of 4-MBA adsorbed on pure TiO(2) NPs. The possible mechanism for the phenomena is also discussed. This study opens up a new dimension for the family of SERS substrates., (Copyright © 2012 Elsevier B.V. All rights reserved.)

A new kind of Ag/Cu2S composite micro/nanostructures has been prepared via a convenient galvanic reduction method. SEM images of these micro/nanostructures showed that Ag nanoparticles with the size of around 50-100 nm were well deposited on the surface of Cu2S micro/nanostructures. The SEM images also indicated that the Ag nanoparticles were preferentially grown on the big polygonal Cu2S microstructures, which could be explained by a localization of the electrons on the surface of the polygonal Cu2S microstructures after the electron transfer step. Owing to the introduction of Ag nanoparticles on the surface of Cu2S micro/nanostructures, the resulting Ag/Cu2S composite micro-nanostructures could be used as a versatile substrate for surface enhanced Raman scattering., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Antibacterial fabric with high thermal stability and mechanical strength is important for personalized protection, especially under the background of coronavirus pandemic (COVID‐19). This paper presents a facile approach toward high‐efficient antibacterial polypropylene spunbonded nonwoven fabrics (SNFs), which are decorated by a composite of graphene oxide embedded with silver nanoparticles (AgNPs/GO) through dip‐coating and in situ reduction effect of pre‐introduced amino‐terminated hyperbranched polymer (HBP‐NH2). Typically, HBP‐NH2 was grafted onto the GO nanosheets, then silver ions were trapped and self‐reduced by the HBP‐NH2 to generate silver nanoparticles decorated GO. The produced AgNPs are uniformly dispersed on the GO with a size of 13 nm. As an antibacterial coating, the Ag/GO composite could tightly wrap the SNFs fibers through the dip‐padding method, capable of enhancing the thermal stability and mechanical property of SNFs. The treated SNFs exhibited excellent antibacterial activities (~99.9%) against both Echerisia coli and Staphylococcus aureus, promising important potential for biomedical and personal protection applications. [ABSTRACT FROM AUTHOR]

In this paper, anatase and rutile TiO2 nanoparticles as well as their mixed crystal phase structure TiO2 nanoparticles were synthesized by a sol-hydrothermal method, and were served as active substrates for surface-enhanced Raman scattering (SERS) study. The results show that the 4-mercaptobenzoic acid probe molecules exhibit different degree SERS enhancements on the surface of different phase structure TiO2 nanoparticles. The mixed crystal structure TiO2 with an appropriate proportion of anatase and rutile phase is favourable to SERS enhancement of adsorbed molecules. These are mainly attributed to the contributions of the TiO2-to-molecule charge transfer mechanism and the mixed crystal effect. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The effect of the ZrO2 crystal form on surface-enhanced Raman scattering (SERS) activity was studied. The ratio of the tetragonal (T) and monoclinic (M) phases of ZrO2 nanoparticles (ZrO2 NPs) was controlled by regulating the ratio of two types of additives in the hydrothermal synthesis method. The SERS intensity of 4-mercaptobenzoic acid (4–MBA) was gradually enhanced by changing the M and T phase ratio in ZrO2 NPs. The degree of charge transfer (CT) in the enhanced 4–MBA molecule was greater than 0.5, indicating that CT was the main contributor to SERS. The intensity of SERS was strongest when the ratio of the T crystal phase in ZrO2 was 99.7%, and the enhancement factor reached 2.21 × 104. More importantly, the proposed study indicated that the T and M phases of the ZrO2 NPs affected the SERS enhancement. This study provides a new approach for developing high-quality SERS substrates and improving the transmission efficiency of molecular sensors. [ABSTRACT FROM AUTHOR]

Abstract: Ag-coating Au colloidal nanoparticles have been prepared by Ag deposition on Au core via the chemical reduction of AgNO3 by hydroquinone. The thickness of Ag shell depends on the Au–Ag molar ratio and the reducing time, which were monitored by the ultraviolet–visible (UV–vis) spectrometry and transmission electron microscopy (TEM). A Raman-active molecules, 4-mercaptobenzoic acid (MBA), are adsorbed onto the surface of 16nm-diameter Au core, and then a 3nm-thick Ag shell coats the MBA modified Au core to form a Au/MBA/Ag sandwich structure. Surface-enhanced Raman scattering (SERS) spectra show that, in the sandwich structure, 3nm-thick Ag shell can effectively enhance the SERS signal of MBA. This is probably caused by the electromagnetic coupling of the Au–Ag double metallic layers. [Copyright &y& Elsevier]

Clean break: Magnetic nanoparticles are fabricated with mesoporous anatase shells, which are biocompatible for enzyme immobilization (see picture; HRP=horseradish peroxidase). The nanobiocatalyst can be easily collected with an external magnet and recycled. Immobilized enzymes with low activity after several cycles can be decomposed with UV radiation and thus the nanoparticles are recyclable for new enzyme immobilization. [ABSTRACT FROM AUTHOR]

Based on bovine serum albumin (BSA)-modified Au NPs, a simple and cost-effective approach was proposed to fabricate an anti-aggregated Au NP sensing platform for the detection of metal ions. It exhibits excellent stability even under highly ionic conditions due to its electrostatic stabilization, as well as the steric stabilization. [ABSTRACT FROM AUTHOR]

• Size-tunable SnS 2 /RGO make facile study the effect of particle size on Li/Na storage. • Ions diffusion coefficient, surface and diffusion capacitive contribution are studied. • Small-sized particle promotes charge/ion transfer and pseudocapacitor contribution. • Controllable dimension promotes fast kinetics for high rate materials. Controlling the particle sizes of electrode materials has long been recognized as an effective way to improve the cycle stability and rate property of both lithium-ion battery (LIB) and sodium-ion battery (SIB). In this paper, a simple one-step hydrothermal process for the preparation of composites with size-tunable tin disulfide on reduced graphene oxide (SnS 2 /RGO) is reported. These novel material allow to comprehensively study the effect of particle sizes on electrochemical properties for LIB and SIB anodes. The structure, morphology, phase compositions, and Li+/Na+ storage behaviors of three different SnS 2 /RGO composites obtained at heat-treatment times of 12, 24 and 48 h are characterized systematically. The electrochemical reaction kinetics is demonstrated by differential charge capacity plots and apparent ion diffusion coefficients. Surface capacitive and diffusion-controlled capacitive contributions to lithium/sodium ions storage are also compared. The results show that the small-sized nanoarchitecture can promote both the charge and ions transfer and thus improve the pseudocapacitor contribution. The reversible capacity maintains at 1211 mAh g−1 for LIB after 200 cycles and 841 mAh g−1 for SIB after 100 cycles, respectively, which is superior to most of the previous reports. This work is expected to provide a profound understanding of composite anodes with controllable dimensions and fast kinetics. The effect of SnS 2 nanoparticle size on the Li and Na storage characteristics of SnS 2 /RGO composite anodes are compared, it show that the decreased particle size promotes the pseudocapacitor contribution, as well as the reversed conversion reaction and structural stability. Image, graphical abstract [ABSTRACT FROM AUTHOR]

By observing the Raman intensity of several molecules (4-mercaptopyridine and 4-mercaptobenzoic acid) adsorbed on the surface of ZnO nanocrystals as a function of particle size in the range of 18–31 nm diameter, we show that a large increase in intensity is observed near 28 nm. This is an indication of a size-dependent charge-transfer resonance. We interpret this effect as due to formation of a charge-transfer complex between a surface-bound exciton and the adsorbed molecule. [ABSTRACT FROM AUTHOR]

In recent years, the use of metal ferrites as sensing materials has aroused more and more interest. However, there is a challenge in the use of cobalt ferrite as ethanol sensor with good gas-sensing properties. In this paper, CoFe 2 O 4 was successfully synthesized by using a facile route. The as-synthesized CoFe 2 O 4 exhibited n-type gas-sensing behavior that the resistance decreases in a reducing gas atmosphere. When applied as sensing materials, CoFe 2 O 4 sensors show good sensitivity to ethanol. At 200 °C working temperature, the response value of CoFe 2 O 4 calcined at 400 °C (CFO-400) sensor to 100 ppm ethanol gas is 110, which is much higher than that of CoFe 2 O 4 ethanol sensor in other studies. Additionally, the CFO-400 sensor shows satisfactory repeatability and stability, as well as high selectivity to ethanol detection compared to other gases. The possible sensing mechanism is investigated in this paper. This work not only displays a facile way to synthesize CoFe 2 O 4 , but also provides potential material for gas sensors in future applications. [Display omitted] • CoFe 2 O 4 nanoparticles were successfully synthesized. • As sensing materials, CoFe 2 O 4 sensors showed good sensitivity to ethanol. • The CoFe 2 O 4 calcined at 400 °C sensor can detect 400 ppb ethanol gas. [ABSTRACT FROM AUTHOR]

[Display omitted] • In 2 O 3 NPs were firstly used as SERS substrates. • The CT mechanism of SERS is confirmed by the spectra. • Providing new semiconductor substrates for SERS applications. Surface-enhanced Raman scattering (SERS) has outstanding merits in biochemical molecular analysis, and the development of new SERS substrates is the focus of research. Herein, In 2 O 3 nanoparticles (NPs) were synthesized by a high temperature pyrolysis method with cubic phase and small particle size at 10 nm. The structures and properties of In 2 O 3 NPs were characterized by X–ray powder diffraction (XRD), transmission electron microscope (TEM) and other characterization methods. Additionally, the SERS spectra of In 2 O 3 -MBA with the enhancement factor (EF) up to 1.22 × 104 is discussed. The results demonstrate that there is a charge transfer (CT) effect revealed between the adsorbed molecules of 4-mercaptobenzoic acid (4-MBA) and the substrates of In 2 O 3 NPs, and it could be excited by long wavelength energy. Based on the In 2 O 3 NPs, the study is beneficial to develop more potential semiconductor SERS substrates. [ABSTRACT FROM AUTHOR]

Abstract Tin dioxide (SnO 2) has attracted extensive research attention as promising anode materials for lithium ion batteries due to high theoretical capacity. However, its application is largely hindered by poor electronic conductivity and drastic volume change during the conversion reaction and alloying processes. Herein, we report a three-dimensional nitrogen-doped graphene aerogel decorating ultra-small SnO 2 nanoparticles (3–6 nm) by a facile one-step hydrothermal process. Nanoscaled SnO 2 nanoparticles facilitate limited volume expansion and shortened lithium diffusion pathways, nitrogen-doping increases the positive charge density of carbon atoms adjacent to the nitrogen atom, while the three-dimensional porous graphene aerogel has excellent electronic conductivity and facile electrolyte infiltration, thus prompting the composite electrode excellent electrochemical performance. When used as bind-free anode electrode, the graphene aerogel/SnO 2 composite delivers a high discharge capacity of 1812.0 mAh g−1 in the initial cycle, and the capacity can retain at 778 mAh g−1 after 100 cycles, demonstrating its promising candidate as anode material for energy storage. Graphical abstract Unlabelled Image Highlights • 3D N-doped GA decorating ultra-small SnO 2 is prepared by hydrothermal reaction. • Ultra-small SnO 2 nanocrystals exhibit high activity and limited volume expansion. • N-doping increases positive charge density of C atoms and electronic conductivity. • 3D porous GA has facile electrolyte infiltration and excellent structure stability. • The composite can be used as electrode directly and shows excellent cyclability. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, graphene-modified Li3V2(PO4)3 composites have been developed as Li-ion battery cathode materials with high specific capacity and excellent cycling stability. The composites are prepared by spray–drying process using graphene oxide nanosheet and citric acid as carbon source. X-ray diffraction patterns demonstrate that the as-prepared samples are well crystallized with orderly monoclinic structures. SEM and TEM images reveal that the 3D network graphene and Li3V2(PO4)3 primary nanoparticles interlace with each other. The citric acid-derived amorphous carbon species interrupt the stacking of graphene sheets and minimize in-plane anisotropy of electronic migration within graphene layers, which would facilitate fast electron migration and Li+ diffusion throughout the micro-sized spherical secondary particles. The discharge capacity of the composite could respectively achieve 131.4 and 181.5mAhg−1 in the voltage range 3.0–4.3V and 3.0–4.8V at 0.1C discharge rate, which almost reach the theoretical capacity of the cathode material. Both of them nearly showed no capacity decay at 0.1C charging and discharging rate after long cycles. [Copyright &y& Elsevier]

Abstract: TiO2 and Mn-doped TiO2 (1%, 3% and 5%) nanoparticles (NPs) were synthesized by a sol-hydrothermal method for surface-enhanced Raman spectroscopy study. When using the 4-mercaptobenzoic acid (4-MBA) as the probing molecule, optimum SERS signals were observed on the Mn–TiO2 (3%) samples. On the 3% Mn doped TiO2 substrate, 4-MBA molecules exhibit a higher SERS intensity by a factor of six as compared with the native enhancement of 4-MBA adsorbed on pure TiO2 NPs. The possible mechanism for the phenomena is also discussed. This study opens up a new dimension for the family of SERS substrates. [Copyright &y& Elsevier]

Abstract: This paper reports the microwave-assisted synthesis of Co3O4 nanomaterials with different morphologies including nanoparticles, rod-like nanoclusters and macroporous platelets. The new macroporous platelet-like Co3O4 morphology was found to be the best suitable for reversible lithium storage properties. It displayed superior cycling performances than nanoparticles and rod-like nanoclusters. More interestingly, excellent high rate capabilities (811mAhg−1 at 1780mAg−1 and 746mAhg−1 at 4450mAg−1) were observed for macroporous Co3O4 platelet. The good electrochemical performance could be attributed to the unique macroporous platelet structure of Co3O4 materials. [Copyright &y& Elsevier]

For surface-enhanced Raman scattering (SERS)-based protein identification, immunoassay, and drug screening, metal sandwich substrates bridged by proteins have been created in the present study. The sandwich architectures are fabricated based on a layer-by-layer (LbL) technique. The first gold monolayer is prepared by the self-assembling of gold nanoparticles on a poly(diallyldimethy-lammonium chloride) (PDDA)-coated glass slide. The second gold or silver layer is produced by the interactions between proteins in the middle layer of the sandwich architecture and the metal nanoparticles. Highly reproducible surface-enhanced resonance Raman scattering (SERRS) and SERS spectra can be obtained by the present gold-protein-gold (Au/Au) and gold-protein-silver (Au/Ag) sandwiches, and we find that the latter yields about 7 times stronger SERRS than the former. Because of contributions from the two metal layers to the SERS, this sandwich strategy holds great potential in highly sensitive and reproducible protein detections. [ABSTRACT FROM AUTHOR]

We have developed a new analytical procedure for label-free protein detection designated "Western SERS", consisting of protein electrophoresis, Western blot, colloidal silver staining, and surface-enhanced Raman scattering (SERS) detection. A novel method of silver staining for Western blot that uses a silver colloid, an excellent SERS-active substrate, is first proposed in the present study. During the process of silver staining, interactions between proteins and silver nanoparticles result in the emergence of SERS of proteins. In the present study, we use myoglobin (Mb) and bovine serum albumin (BSA) as model proteins. From different protein bands on a nitrocellulose (NC) membrane, we have observed surface-enhanced resonance Raman scattering (SERRS) spectra of Mb and SERS spectra of BSA. The proposed technique offers dual advantages of simplicity and high sensitivity. On one hand, after the colloidal silver staining, we can detect label-free multi-proteins directly on a NC membrane without digestion, extraction, and other pretreatments. On the other hand, the detection limit of the Western SERS is almost consistent with the detection limit of colloidal silver staining, and the SERRS detection limit of Mb is found to be 4 ng/band. This analytical method, which combines the technique of protein separation with SERS, may be a powerful protocol for label-free protein detection in proteomic research. [ABSTRACT FROM AUTHOR]

Abstract: In this paper cobalt ferrite nanoparticles have been synthesized by an improved chemical precipitation, called spraying co-precipitation. TG/DTA, XRD, BET and TEM were used to analyse the structure characteristics of CoFe2O4 nanoparticles. The results show that the CoFe2O4 nanoparticles prepared by spraying co-precipitation have smaller size and more uniform than those prepared by regular co-precipitation. The mechanism of spraying co-precipitation was investigated. [Copyright &y& Elsevier]

Abstract: We describe a simple method to synthesize triangular silver nanoparticles by photoreducing the silver ions by citrate. A noteworthy difference of the present method as compared with the previous photo-induced methods is that good shape control over the nanoparticles can be realized in the absence of soft templates or polymer directing agents. The formation process of the silver nanoparticles was investigated by UV–vis spectroscopy and transmission electron microscopy (TEM). It was found that the concentration of reactant plays important role in the morphology control of produced silver nanoparticles. As one of the applications of these nanoparticles, they were used as surface-enhanced Raman scattering substrates and 1,4-bis[2-(4-pyridyl)ethenyl]-benzene (BVPP) was used as a Raman probe to evaluate the enhancement ability of the triangular silver nanoparticles. [Copyright &y& Elsevier]

Abstract: Ag/CdTe nanocomposite was prepared via self-organization process by electrostatic interaction between positively charged CdTe quantum dots and negatively charged Ag nanoparticles and examined with respect to their optical properties. The positively charged CdTe quantum dots and negatively charged Ag nanoparticles were synthesized separately by modifying nanoparticles surface with cationic and anionic thiol compounds, respectively. The result showed that the mixing ratio of Ag nanoparticles to CdTe quantum dots is an important parameter for controlling resulting composites. The resulting solution is optically transparent if one component is in excess. Photoluminescence of CdTe quantum dots undergoes considerably quenching if CdTe nanocrystals are in excess and SERS spectra of BVPP absorbed on Ag colloid became stronger if Ag nanoparticles are in excess. Nevertheless, while the ratio is approximately 1, micrometer-sized solid composite is obtained with the elapse of 1h after mixing. SERS spectra for solid composite only exhibit the signals of the CdS nanocrystal which reflected that prolonged refluxing during the synthesis leads to a partial hydrolysis of the thiols and to the incorporation of the sulfur from the thiol molecules into the the growing nanoparticles to form mixed CdTe(S) nanocrystal, similar to CdTe/CdS core/shell structure. From the results, we conclude that optical properties of Ag/CdTe are dependent on the mixing ratio of both nanoparticles. [Copyright &y& Elsevier]

Abstract: Using the Tollens-soaked sintered silica colloidal crystals as template, we developed a simple method of preparing Ag nanoparticles coated silica colloidal crystals (ANCSCC) and polymer-Ag nanoparticles composite macroporous films. In our experiment, the Ag nanoparticles are mainly distributed on the surface of the silica spheres instead of in the voids of the colloidal crystals due to the Ag (NH3)2 + ions are mainly coming from the silica microspheres. As one of the application of such composite colloidal crystals, the ANCSCC are used as the surface-enhanced Raman scattering substrates and large enhancements were observed. The ANCSCC also can be used as template to construct more complex structures of polymer-Ag nanoparticles composite macroporous films. It can be anticipated that except these samples can be used as Raman analysis and Raman image, our method introduced here will also provide a powerful platform for patterning other metal particles (such as Au or platinum) sensitized to the colloidal particles used in the colloidal crystals or preparing other novel composite structures due to its convenience and controllability. [Copyright &y& Elsevier]

Abstract: A substrate for surface-enhanced Raman scattering (SERS) has been developed. Based on the surface-catalyzed reduction of Ag+ by citrate on the silver nanoparticles surface under light irradiation, small silver seeds on a quartz slide can be enlarged. The optical properties and characteristics of the silver films have been investigated by ultraviolet-visible spectroscopy, scan electron microscope and atomic force microscopy (AFM). The results indicate that the particle size and shape are different at different reduction time. At the first 3 h, some triangular and hexagonal nanoparticles formed; with the reduction proceeding, the shape of the silver particles became irregular and the size became larger. The silver films obtained are very suitable as SERS active substrate. The relationship between SERS intensity and the reduction time has been investigated for 1,4-bis[2-(4-pyridyl)ethenyl]-benzene molecule adsorbed on the silver film. The SERS intensity reached a maximum at 8 h reduction. The AFM measurements indicate that roughness features with an average size of 100 nm are present on the surface, which yielded the strongest SERS signal. Pyridine was used as a probe molecule to investigate the enhancement factor (EF) of the silver films. According to the formalism of Tian and co-workers, the EF of the silver films is estimated to be 3.4×105. The silver film that can remain active for more than 50 days would seem to be suitable for various analytical applications. [Copyright &y& Elsevier]

Abstract: A new SERS-active silver film prepared by directly depositing silver nanoparticles on glass is reported. The spontaneous reduction of Ag+ ions in -dimethylformamide (DMF) (in the absence of a protecting agent) leads to the deposition of silver nanoparticles on clean glass surfaces in contact with the solution. The observed optical micrographs and AFM images show that the arrangement of the nanoparticles is inhomogeneous and the particles appear to be closely packed. These films are shown to be excellent substrates for SERS measurements, demonstrating significant enhancement, good stability, and trace detection capability. The SERS enhancement of the silver films with different deposition times was compared and found that the 8-h film gives the largest enhancement ability with an enhancement factor estimated at about 109. It is also found that the silver films stored for 80 days in air show no significant degradation in their sensitivity. [Copyright &y& Elsevier]

A novel method for the preparation of thin films of Ag nanoparticles is reported. Using mercaptoacetic acid as the stabilizing agent, AgI nanoparticles were prepared in aqueous solution. And based on electrostatic interactions, the thiol-passivated AgI nanoparticles were assembled in a self-assembled film by alternative deposition with a cationic polyelectrolyte. Then the AgI nanoparticles in the composite film were reduced by NaBH4, which resulted in the formation of a thin film of Ag nanoparticles. UV-visible spectra and X-ray photoelectron spectroscopy data confirmed the transformation from AgI to Ag. Atomic force microscopy (AFM) showed that the formed Ag nanoparticles distributed on the film homogeneously. Surface-enhanced Raman spectroscopy (SERS) measurement indicated that the prepared thin films could be used as effective SERS substrates. The reduction process was also carried out by UV light at selective surface regions, which resulted in the formation of patterned nanoparticle arrays. [Copyright &y& Elsevier]

• A novel hollow sandwich spherical graphene/Si (Sandwich-G/Si) composite is reported. • Si nanoparticles are inserted in between spherical graphene shells by covalent binding. • It inhibits Si aggregation and expansion, and promotes e- and Li+ transport kinetics. • An ultrastable cyclability with 1085.6 mAh/g after 500 cycles is obtained at 100 mA/g. In order to solve problematic issues of silicon-based anode such as agglomeration, poor conductivity and volumetric expansion, a novel hollow spherical composite with small-sized silicon nanoparticles sandwiching in between spherical graphene shells with chemical bonding has been constructed through electrostatic layer-by-layer assembly and subsequent in-situ aluminothermic reduction. This kind of elaborately designed sandwich structure not only inhibits aggregation and volume expansion of the silicon nanoparticles effectively, but also shorten electronic and ionic transport channels. Especially, the covalent binding between active Si component and conductive graphene matrix can significantly enhance the structural integrity and facilitate the reaction kinetics during repeated discharge/charge cycles. Benefiting from multiple merits, the proposed hollow sandwich spherical structured graphene/Si composite electrode delivers ultra-stable lithium storage performance with a high capacity of 1085.6 mAh g−1 remained after 500 deep charge–discharge cycles at 100 mA g−1. The dramatically enhanced electrochemical performance of the sandwich spherical structured graphene/Si composite shed light on its application potential as the promising anode candidate for next-generation lithium ion batteries with high energy/power densities and ultra-long span life. [ABSTRACT FROM AUTHOR]