Search

Psychological stress is a major contributor to individual health disparities. Accurate and quantitative detection of stress markers is crucial preventing mental health related problems. Supramolecular chemistry is widely used in drug delivery, catalysis, sensors and other applications. However, due to the difficulty of host functionalization such as cyclodextrins and solid-state pillar[n], it is still a challenge to directly realize the detection of guests through host-guest recognition behavior. Here, we reported an atom transfer radical polymerization (ATRP) fluorescent biosensor for direct and selective detection of guest molecule stress marker cortisol, translating molecular recognition behavior into quantifiable detection signals. Realizes quantitative chemical detection and builds a portable and affordable sensing platform for quantitative detection of target molecules without complex cross-linking steps. Overcomes the disadvantages of traditional methods that require the use of antibodies or are difficult to functionalize during the host-guest recognition process. This ATRP fluorescent biosensor was fabricated by employing zinc phthalocyanine (ZnPc) as a photocatalyst under 630 nm wavelength radiation, β-CD-Br 15 as a macromolecular initiator, and fluorescein O-methacrylate (FMA-O) as a monomer for polymerization. The system provides ultra-high sensitivity for the detection of cortisol (limit of detection 0.47 ng/mL) and specificity for the detection of cortisol in the presence of interfering substances such as progesterone and urea. Selective and real sample experiments confirm the specificity and scalability of this mechanism can also be customized by the rational design of the host-guest complex to quantitatively detect various molecules. This study confirms the feasibility of using a cyclodextrin-centered macromolecular initiator as a capture and label-free fluorescent biosensor for cortisol, a stress biomarker., 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 © 2024. Published by Elsevier B.V.) more...

Assembling functional molecules on the surface of an enzyme electrode is the most basic technique for constructing a biosensor. However, precise control of electron transfer interface or electron mediator on the electrode surface remains a challenge, which is a key step that affects the stability and sensitivity of enzyme-based biosensors. In this study, we propose the use of controllable free radical polymerization to grow stable 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) polymer as electron mediator on enzyme surface for the first time. Through scanning electron microscopy (SEM), Raman spectroscopy, electrode surface coverage measurement, static contact angle (SCA), and a series of electrochemical methods, it has been demonstrated that the TEMPO-based enzyme electrode exhibits a uniform hydrophilic morphology and stable electrochemical performance. Furthermore, the results show that the sensor demonstrates high sensitivity for detecting glucose biomolecules in artificial sweat and serum. Attributing to the quantitative and controllable radical polymerization of TEMPO redox assembled enzyme electrode surface, the as-proposed biosensor providing a use, storage, and inter-batch sensing stability, providing a vital platform for wearable/implantable biochemical sensors., Competing Interests: Declaration of competing interest There are no known conflicts of interest., (Copyright © 2024 Elsevier B.V. All rights reserved.) more...

Accurate and quantitative detection of pre-eclampsia markers is crucial in reducing pregnancy mortality rates. This study introduces a novel approach utilizing a fluorescent biosensor by the immunosorbent atom transfer radical polymerization (immuno-ATRP) assay to detect the pre-eclampsia protein marker CD81. The critical step used in this sensor is the novel signal amplification strategy of fluorescein polymerization mediated by ferritin-enhanced controlled radical polymerization, which combines with a traditional enzyme-linked immunosorbent assay (ELISA) to further reduce the detection limit of the CD81 protein concentration. The fluorescence intensity was linear versus logarithmic CD81 protein concentration from 0.1 to 10,000 pg mL -1 , and the detection limit was 0.067 pg mL -1 . Surprisingly, in 30% normal human serum (NHS), the sensor can also detect target protein over 0.1-10,000 pg mL -1 , with 0.083 pg mL -1 for the detection limit. Moreover, the proposed biosensor is designed to be cost-effective, making it accessible, particularly in resource-limited settings where expensive detection techniques may not be available. The affordability of this method enables widespread screening and monitoring of preeclampsia, ultimately benefiting many pregnant women by improving their healthcare outcomes. In short, developing of a low-cost and susceptible direct detection method for preeclampsia protein markers, such as CD81, through the use of the immuno-ATRP assay, has significant implications for reducing pregnancy mortality. This method holds promise for early detection, precise treatment, and improved management of preeclampsia, thereby contributing to better maternal and fetal health. more...

Human T-lymphotropic virus type II (HTLV-II) is a crucial retrovirus that is closely associated with a variety of human diseases. Herein, an ultrasensitive fluorescent HTLV-II DNA detection strategy was developed for the first time based on magnetic nanoparticles (MNPs) and atom transfer radical polymerization (ATRP) amplification. In this approach, hairpin DNA probes (pDNA) labelled with 5' thiol and 3' azide group terminally were immobilized on amino group modified MNPs surface through sulfo-N-succinimidyl-4-maleimidobutyrate sodium salt (sulfo-GMBS) cross-linkers. In the presence of target DNAs (tDNA), pDNA hybridized with tDNA to form double-stranded DNA, and therefore its azide group was away from the MNPs surface. Subsequently, to initiate ATRP reaction, initiators were introduced into the pDNA by a Cu (I)-catalyzed alkyne-azide cycloaddition (CuAAC). Then, large numbers of 9-anthracenylmethyl methacrylate polymer (pAMMA) were successfully labelled on the MNPs surface, resulting in significant amplification of the fluorescence signal. Under optimized conditions, the fluorescence signal was proportional to the logarithm of the concentration of tDNA over the range from 1 fM to 1 nM, with a detection limit of 0.22 fM. Moreover, this strategy was capable of discriminating mismatched bases and detecting HTLV-II DNA in human serum samples. By virtue of the high sensitivity, selectivity, simplicity and economy, this ultrasensitive biosensor demonstrates great potential for biomedical research and early clinical diagnosis., (Copyright © 2019 Elsevier B.V. All rights reserved.) more...

A green electrochemical biosensor was developed based on metal-organic framework (MOF)-catalyzed atom transfer radical polymerization (ATRP) for quantifying miRNA-21, used as the proof-of-concept analyte. Unlike conventional ATRP, Mn-PCN-222 (PCN, porous coordination network) could be used as an alternative for green catalyst to substitute traditional catalysts. First, poly (diallyldimethylammonium chloride) (PDDA) was fixed on the surface of the indium tin oxide (ITO) electrode, and then the Mn-PCN-222 was linked to ITO electrode via electrostatic binding with PDDA. Next, aminated ssDNA (NH2-DNA) was used to modify the electrode further by amide reaction with Mn-PCN-222. Then, the recognition and hybridization of NH2-DNA with miRNA-21 prompt the generation of DNA−RNA complexes, which further hybridize with Fc-DNA@β-CD-Br15 and permit the initiator to be immobilized on the electrode surface. Accordingly, β-CD-Br15 could initiate the polymerization of ferrocenylmethyl methacrylates (FcMMA) under the catalysis of MOF to complete the ATRP reaction. FcMMA presented a distinct electrochemical signal at ~ 0.33 V. Taking advantage of the unique multi-site properties of β-CD-Br15 and the efficient catalytic reaction induced by Mn-PCN-222, ultrasensitive detection of miRNA-21 was achieved with a detection limit of 0.4 fM. The proposed electrochemical biosensor has been applied to the detection of miRNA-21 in serum samples. Therefore, the proposed strategy exhibited potential in early clinical biomedicine. [ABSTRACT FROM AUTHOR] more...

A novel fluorescence assay is proposed through activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP) strategy for alkaline phosphatase (ALP) activity detection. First of all, 2-bromo-2-methylpropionic acid (BMP) was employed as the initiator to modify on the surface of the magnetic nanoparticle (Fe3O4-MNP) by amide bonding. Then, ascorbic acid (AA) produced by ALP catalyzed the phosphate group removal from L-ascorbic acid 2-phosphate sesquimagnesium salt hydrate (AAPS), which underwent a redox reaction with Cu(II) and the product Cu(I) triggered the ARGET ATRP reaction. Finally, a strong fluorescent signal could be detected at 514 nm due to numerous fluorescent monomers being grafted to the Fe3O4-MNPs surface (Ex = 490 nm, Em = 514 nm). Under optimal experimental conditions, the linear range of this fluorometric assay for ALP activity was 1–80 mU mL−1, and the detection limit was 0.68 mU mL−1. The method exhibited excellent selectivity and satisfactory results were obtained in the inhibition rate and human serum experiments. Therefore, this ALP activity detection strategy has great potential for clinically relevant disease detection and drug screening. A novel fluorescence strategy for alkaline phosphatase activity detection based on the dephosphorylation property of alkaline phosphatase and ARGET ATRP reaction. [ABSTRACT FROM AUTHOR] more...

In this paper, a high sensitivity and accuracy biosensor for CEA detection based on atom transfer radical polymerization (ATRP) with β-cyclodextrin (β-CD) and 2-bromoisobutyryl bromide (BIBB) as a macroinitiator is reported for the first time. Carcinoembryonic antigen (CEA), as a tumor-associated antigen, can be of great significance in the diagnosis of illness. Herein, thiolated CEA-aptamer 1 (Apt 1) at the 5′-terminal is first immobilized on amino magnetic beads (MBs) via a cross-linking agent to specifically recognize the antigen of CEA. After the sandwich-type structure formed, β-CD, with a bridging effect, is linked to the carboxylation CEA-aptamer 2* (Apt 2*) and BIBB via esterification reaction and substitution reaction, respectively. Remarkably, the combination of β-CD and the initiators BIBB can provide a large number of active sites for monomers and significantly amplify the fluorescent signal. Under optimum experimental conditions, the proposed biosensor for detecting CEA has a strong linear relationship in the wide detection range of 1.0 × 10−15–1.0 × 10−7 g mL−1 (R2 = 0.9989), and it is capable of detecting as low as 6.76 ag mL−1 CEA. Furthermore, the fluorescence biosensor exhibits splendid analytical performance in practical sample analysis. More importantly, the excellent sensitivity with outstanding anti-interference properties of this proposed biosensor makes it of great potential in the field of bioanalytical applications. [ABSTRACT FROM AUTHOR] more...

In this work, a new method of CYFRA21-1 DNA (tDNA) detection based on electrochemically mediated atom transfer radical polymerization (e-ATRP) and surface-initiated reversible addition-fragmentation chain transfer polymerization (SI-RAFT) cascade polymerization and AgNP deposition is proposed. Firstly, the peptide nucleic acid (PNA) probe is captured on a gold electrode by Au-S bonds for specific recognition of tDNA. After hybridization, PNA/DNA strands provide high-density phosphate groups for the subsequent ATRP initiator by the identified carboxylate-Zr4+-phosphate chemistry. Then, a large number of monomers are successfully grafted from the DNA through the e-ATRP reaction. After that, the chain transfer agent of SI-RAFT and methacrylic acid (MAA) are connected by recognized carboxylate-Zr4+-carboxylate chemistry. Subsequently, through SI-RAFT, the resulting polymer introduces numerous aldehyde groups, which could deposit many AgNPs on tDNA through silver mirror reaction, causing significant amplification of the electrochemical signal. Under optimal conditions, this designed method exhibits a low detection limit of 0.487 aM. Moreover, the method enables us to detect DNA at the level of PCR-like and shows high selectivity and strong anti-interference ability in the presence of serum. It suggests that this new sensing signal amplification technology exhibits excellent potential of application in the early diagnosis of non-small cell lung cancer (NSCLC). [ABSTRACT FROM AUTHOR] more...

An electrochemiluminescence approach based on surface-initiated reversible addition–fragmentation chain transfer (SI-RAFT) was developed for miRNA-21 detection for the first time. The SI-RAFT polymerization generates polymer chains with functional groups that are used to recruit luminol, enabling strong ECL signal output with low concentrations of miRNA-21, and greatly improving the detection sensitivity. [ABSTRACT FROM AUTHOR] more...

A novel electrochemical biosensor was reported for the first time to achieve highly sensitive DNA detection based on photoinduced atom transfer radical polymerization (photoATRP). In this work, PNA was applied as the capture probe to specifically recognize the target DNA (TDNA), and we utilized lung cancer DNA as TDNA. The ATRP initiator was introduced to the electrode surface via phosphate-Zr4+-carboxylate chemistry. PhotoATRP was activated under blue light irradiation based on a photoinitiator I2959, which produced free radicals via homolytic cleavage. Subsequently, Cu2+ was reduced to Cu+ with the assistance of the free radicals, and numerous electroactive probes were grafted onto the electrode surface. Under optimal conditions, the limit of detection (LOD) of this method was 3.16 fM (S/N = 3, R2 = 0.992), and the linear range was from 10 fM to 1.0 nM. More importantly, the preparation process of this biosensor was simple and less laborious with a low background signal, suggesting good potential in practical applications. [ABSTRACT FROM AUTHOR] more...

Convenient and sensitive detection of biomolecules is of great significance to disease diagnosis. In this work, a metal‐free photoinduced atom transfer radical polymerization (photoATRP) by a reductive quenching pathway as a novel strategy is applied to achieve lung cancer DNA detection. Thiolated PNA is exploited to specifically recognize target DNA, and the initiator of photoATRP is linked to the electrode surface via phosphate‐Zr4+‐carboxylate. Under the excitation of blue light, the reductive quenching pathway is activated with eosin Y (EY) as photoredox catalyst and N,N,N′,N′′,N′‐pentamethyldiethylenetriamine (PMDETA) as electron donor, and numerous polymeric chains are formed. Under optimal conditions, the linear range of this strategy is from 0.1 pm to 10 nm (R2=0.989) with a limit of detection (LOD) of 1.4 fm (14 zmol in 10 μL). The variety of possible light sources for photoATRP and simple operation endow this biosensor with great potential for practical applications. [ABSTRACT FROM AUTHOR] more...

A highly sensitive method is described for determination of DNA. It is based on dual signal amplification, viz. (a)DNA-templated metal deposition, and (b) thermally initiated surface-initiated reversible addition−fragmentation chain transfer (SI-RAFT) polymerization. A peptide nucleic acid (PNA) with a terminal thiol group was grasped onto a gold electrode by self-assembly. The modified electrode serves as a probe to selectively capture target DNA (tDNA). In the next step, Zr(IV) ions are bound to the phosphate groups of the tDNA. A chain-transfer agent (CTA) for thermally initiated SI-RAFT polymerization, 4-cyano-4-(phenylcarbonothioylthio)pentanoic acid (CPAD), was immobilized on tDNA by conjugation of the carboxy group to Zr(IV) ions. Subsequently, numerous monomers of glycosyloxyethyl methacrylate (GEMA) were connected to the CPAD by thermally initiated SI-RAFT polymerization with azobisisobutyronitrile (AIBN) serving as the free-radical thermal initiator. Afterwards, hydroxyl groups of the GEMA were oxidized to aldehyde groups reacting with sodium periodate, and silver nanoparticles were further introduced on the surface of electrode via "silver mirror reaction". This results in a large electrochemical signal amplification. Under optimized conditions, the electrochemical signal (best measured at a working potential of 0 V vs. SCE (KCl; 3 M)) increases linearly with the logarithm of tDNA concentration in the 10 to 106 aM concentration range. The detection limit is as low as 5.6 aM (~34 molecules in a 10 μL sample). This is lower by factors between 2 and 1800 times than detection limits of most other ultra-sensitive electrochemical DNA assays. [ABSTRACT FROM AUTHOR] more...

Since the oversecretion of protein kinases is indicative of multiple human diseases, the screening of their activities is quite important to clinical diagnosis and targeted therapy. In this work, an ultrasensitive peptide-based electrochemical biosensor was presented for the detection of protein kinase activity by using the reversible addition-fragmentation chain transfer (RAFT) polymerization technique as a signal amplification strategy. First, the substrate peptides were tethered to a gold electrode surface via the thiol terminals. After the phosphorylation of substrate peptides by protein kinases, the carboxyl group-containing dithiobenzoates were labeled to the phosphorylated sites via the robust phosphate-Zr4+-carboxylate linkages. Finally, the RAFT polymerization was initiated using ferrocenylmethyl methacrylates (FcMMAs) and dithiobenzoates as the monomers and the RAFT agents, respectively. The grafting of ferrocenyl polymer chains efficiently recruits a great number of electro-active Fc probes to each phosphorylated site, leading to a drastic amplification of the electrochemical signal. With PKA (protein kinase A) as the target, the detection limit of the peptide-based biosensor can be as low as 1.05 mU mL−1. Moreover, it can selectively differentiate the target from other interferents and is applicable for the screening of potential inhibitors as well as the detection of protein kinase activity in complex cell lysates. Therefore, the peptide-based biosensor shows great promise as a universal tool for protein kinase activity detection and inhibitor screening. Image 1 • A peptide-based electrochemical biosensor is shown for protein kinase activity assay. • The RAFT polymerization is exploited as a novel signal amplification strategy. • The RAFT polymerization-based strategy is operationally simple and low-cost. • This assay is highly sensitive and selective and can be used for inhibitor screening. • It is applicable for protein kinase activity assay in complex biological samples. [ABSTRACT FROM AUTHOR] more...

An original electrochemical biosensor via Cu-mediated near-infrared light (NIR) polymerization was reported for highly sensitive nucleic acid detection. Lung cancer DNA as nucleic acid model was specifically recognized via phosphate-free peptide nucleic acid (PNA). Subsequently, initiators of polymerization were attached to PNA/DNA heteroduplex under the assistance of phosphate-Zr4+-carboxylate. Cu 2 (OH)PO 4 and H 2 O 2 system was triggered off under the irradiation of NIR light, and then hydroxyl radicals (•OH) were produced. At the same time, carbon-based radicals were also generated through the reaction between •OH and methacrylic monomers of polymerization, which initiated the photoinduced polymerization. Then, numerous ferrocene-based methacrylic monomers were modified on the surface of electrode. The limit of detection was improved to 2.6 fM with linear range from 0.01 pM to 1000 pM (R2 = 0.993), and the minimum molar number of lung cancer DNA was 26 zmol (in 10 μL). This biosensor also presented portable and cost-efficient feature due to simple operation and ubiquitous light, and no phototoxicity and good tissue penetration of NIR also endowed this strategy great potential in biological detection. • NIR was first designed for highly sensitive nucleic acid detection. • Cu 2 (OH)PO 4 was firstly used to activate photoinduced polymerization. • The operation of this biosensor was simple. • This biosensor presented a portable and cost-efficient feature. [ABSTRACT FROM AUTHOR] more...

Thrombin, a coagulation system protease, is a key enzyme involved in the coagulation cascade and has been developed as a marker for coagulation disorders. However, the methods developed in recent years have the disadvantages of complex operation, long reaction time, low specificity and sensitivity. Meanwhile, thrombin is at a lower level in the pre-disease period. Therefore, to accurately diagnose the disease, it is necessary to develop a fast, simple, highly sensitive and specific method using signal amplification technology. We designed an electrochemical biosensor based on photocatalytic atom transfer radical polymerization (photo-ATRP) signal amplification for the detection of thrombin. Sulfhydryl substrate peptides (without carboxyl groups) are self-assembled to the gold electrode surface via Au–S bond and serve as thrombin recognition probes. The substrate peptide is cleaved in the presence of thrombin to generate –COOH, which can form a carboxylate-Zr(IV)-carboxylate complex via Zr(IV) and initiator (α-bromophenylacetic acid, BPAA). Subsequently, an electrochemical biosensor was prepared by introducing polymer chains with electrochemical signaling molecules (ferrocene, Fc) onto the electrode surface by photocatalytic (perylene, Py) mediated ATRP using ferrocenylmethyl methacrylate (FMMA) as a monomer. The concentration of thrombin was evaluated by the voltammetric signal generated by square wave voltammetry (SWV), and the result showed that the biosensor was linear between 1.0 ng/mL ∼ 10 fg/mL, with a lower detection limit of 4.0 fg/mL (∼0.1 fM). Moreover, it was shown to be highly selective for thrombin activity in complex serum samples and for thrombin inhibition screening. The biosensor is an environmentally friendly and economically efficient strategy while maintaining the advantages of high sensitivity, anti-interference, good stability and simplicity of operation, which has great potential for application in the analysis of complex samples. [Display omitted] • A thrombin sensor based on atom transfer radical polymerization was designed. • Photo-ATRP based on catalyst perylene was first applied in biosensor. • The biosensor has highly sensitive to thrombin with a detection limit of 4.0 fg/mL. • The biosensor has good anti-interference ability in 0–20% normal human serum. [ABSTRACT FROM AUTHOR] more...

An ultrasensitive fluorescence method for early diagnosis of lung cancer via Nafion-initiated atom transfer radical polymerization (ATRP) is reported, in this paper. In the proposed method, thiolated peptide nucleic acid (PNA) is modified to amino magnetic beads (MBs) via a cross-linking agent to specifically capture target DNA (tDNA), and the initiator (Nafion) of ATRP is attached to PNA/DNA heteroduplexes based on the phosphate groups of the tDNA and sulfonate groups of Nafion via phosphate-Zr4+-sulfonate chemistry. Nafion as a macroinitiator of ATRP possesses multiple C–F active sites to initiate polymerization, and numerous polymeric chains that significantly amplify the fluorescent signal are formed. Under optimal conditions, a good linear relationship is obtained in the range of 0.1 nM–0.1 fM with correlation coefficients of 0.9975, and the detection limit is as low as 35.5 aM (∼214 molecules). The proposed strategy has several advantages of simplicity, cost-effectiveness, selectivity and sensitivity. More importantly, the anti-interference results demonstrate that the proposed Nafion-initiated ATRP strategy has great potential in bioanalytical applications. An ultrasensitive fluorescence method for early diagnosis of lung cancer via Nafion-initiated atom transfer radical polymerization (ATRP) was reported. Image 1 • Nafion, as the initiator, has multiple active sites to generate free radical and can bind more monomers. • A novel DNA detection for early diagnosis of lung cancer based on Nafion-initiated ATRP was reported for the first time. • This detection has a fairly simple, gentle, cost-effectiveness process with high selectivity and interference immunity. [ABSTRACT FROM AUTHOR] more...

Ultrasensitive aptamer fluorometric detection of gamma-interferon by dual ATRP amplification. • A new aptamer fluorometric protein sensor was fabricated by dual ATRP amplification. • This supersandwich fluorescence method has great potential in realize ultrasensitive protein (IFN-γ) detection in human serum. • This novel preparation is simple, gentle and convenient. Exploiting biological detection methods with high selectivity and sensitivity has been an urgent demand for low abundance biomolecules. Herein, an ultrasensitive aptamer fluorometric method of protein detection was fabricated via a sequential dual atom transfer radical polymerization (ATRP). For the first time, surface-initiated dual ATRP was utilized to make the fluorometric signal amplification for gamma-interferon (IFN- γ) protein assay. Two aptamers are used as protein probes, which can form a high stable and selective "aptamer/ protein/aptamer" sandwich structure. One aptamer probe is attached on superparamagnetic nanoparticle via surface self-assembled, the other one is linked with initiators of dual ATRP amplification by click chemistry formed triazole group. With large numbers of fluorescein-o-acrylate grown directly on a nanoparticle surface, a convenient "aptamer/protein/aptamer-polymer" supersandwich sensor was fabricated. Under optimal conditions, IFN- γ can be assayed with detection limit down to 0.178 fM in PBS buffer (equals to 1.072 ˣ103 IFN-γ molecules). Even in complex human serum, IFN-γ can also be detected with the limit of 1.54 fM, equals to 9.275 ˣ103 IFN-γ molecules. Results show a great potential in real ultrasensitive protein detection for its high selectivity, efficiency and stability. Besides, this proposed sensing method, which combines the advantages of superparamagnetic nanomaterial and chemically catalyzed surface-initiated dual ATRP polymerization, compared to the traditional signal amplify methods, is novel, more convenient, simpler and enzyme-free cascade amplification. [ABSTRACT FROM AUTHOR] more...

Graphical abstract Highlights • A new fluorescent DNA click reactant was fabricated by the combination of two commercial modified DNA fragments. • This supersandwich fluorescence method can realize ultrasensitive protein detection via DNA based click polymerization. • This novel preparation is simple, gentle and convenient. Abstract With the demanding of low abundance biomolecule detection increase, to develop novel signal amplification strategies and simple, convenient, sensitive sensors are necessary for ultrasensitive bioassays in disease diagnosis, drug therapy and environmental monitoring. Herein, for the first time, a new “aptamer/protein / aptamer-polymer” supersandwich fluorescence sensor for the ultrasensitive protein detection via DNA based click polymerization was fabricated. During the fabrication process, a new fluorescent DNA click reactant was prepared through a quick, gentle and spontaneous combination of two DNA fragments. Functionalized Fe 3 O 4 magnetic nanoparticles provide abundant sites due to their large surface area, and enable the sensor prepared easily, without the need for complicated synthesis and purification steps. Under optimal conditions, this proposed supersandwich strategy could detect IFN-γ protein down to 0.175 fM with a broad concentration range from 0.01 pM to 10 nM. Meanwhile, good detection limit of 1.63 fM in fetal bovine serum indicates that this convenient, sensitive and high selective sensor shows a great potential in clinical ultrasensitive protein detection. [ABSTRACT FROM AUTHOR] more...

In this work, a biosensor for ultrasensitive detection of glucose via electrochemically mediated atom transfer radical polymerization (eATRP) was firstly reported in the field of biosensing analysis. Firstly, 4-mercaptophenylboronic acid was immobilized onto Au electrode surface via Au S bond to recognize glucose by producing 5-membered cyclic boronic ester. Then initiators of atom transfer radical polymerization were introduced to the electrode surface by the reaction between 2-bromoisobutyryl bromide and the remaining hydroxyl groups of glucose to produce the alkyl halide initiation site. The monomer began to graft onto the electrode surface, and an electrochemical potential was applied to activate the copper catalyst for the formation of polymeric chains which were labeled numerous electroactive probes ferrocene. The square wave voltammetry was applied to monitor electrochemical signal of quantitatively labeled ferrocene. Under optimal conditions, this strategy for ultrasensitive detection of glucose presented a good linear relationship between oxidation current of ferrocene and logarithm of glucose concentrations in the range from 1.0 nM to 10 μM with an extremely low limit of detection of 0.32 nM (R 2  = 0.996). In addition, this strategy showed good specificity for glucose detection in physiological conditions and also showed high reliability in human serum. [ABSTRACT FROM AUTHOR] more...

Protein kinases play a pivotal role in cellular regulation and signal transduction, the detection of protein kinase activity and inhibition is therefore of great importance to clinical diagnosis and drug discovery. In this work, a novel electrochemical platform using the electrochemically mediated polymerization as an efficient and cost-effective signal amplification strategy is described for the highly sensitive detection of protein kinase activity. This platform involves 1) the phosphorylation of substrate peptide by protein kinase, 2) the attachment of alkyl halide to the phosphorylated sites via the carboxylate-Zr 4+ -phosphate chemistry, and 3) the in situ grafting of electroactive polymers from the phosphorylated sites through the electrochemically mediated atom transfer radical polymerization (eATRP) at a negative potential, in the presence of the surface-attached alkyl halide as the initiator and the electroactive tag-conjugated acrylate as the monomer, respectively. Due to the electrochemically mediated polymerization, a large number of electroactive tags can be linked to each phosphorylated site, thereby greatly improving the detection sensitivity. This platform has been successfully applied to detect the activity of cAMP-dependent protein kinase (PKA) with a detection limit down to 1.63 mU mL −1 . Results also demonstrate that it is highly selective and can be used for the screening of protein kinase inhibitors. The potential application of our platform for protein kinase activity detection in complex biological samples has been further verified using normal human serum and HepG2 cell lysate. Moreover, our platform is operationally simple, highly efficient and cost-effective, thus holding great potential in protein kinase detection and inhibitor screening. [ABSTRACT FROM AUTHOR] more...

Convenient and sensitive detection of biomolecules is of utmost importance in the field of early disease screening. In this study, a Rose Bengal-Mediated photoinduced atom transfer radical polymerization (photoATRP) method was used to achieve highly sensitive detection of target DNA (tDNA). The tDNA was specifically recognized using PNA with terminal modified sulfhydryl groups, and the initiator α-bromophenylacetic acid (BPAA) was attached to the electrode surface via a phosphate-Zr4+-carboxylate acid structure. Under the excitation of blue light, rose bengal (RB) acts as a photocatalyst, β-nicotinamide adenine dinucleotide (NADH) as an electron donor, and ferrocenylmethyl methacrylate (FMMA) as a monomer to activate the photoATRP reaction and generate a large number of electroactive polymer chains on the electrode surface. Under optimal conditions, the method can be used for the quantitative analysis of tDNA in the concentration range of 1–105 fM (R2 = 0.994) with a limit of detection (LOD) of 0.115 fM. This metal-free mediated photoATRP biosensor, with low cost and environmental friendliness, has great potential in the field of highly sensitive biomolecule detection. [Display omitted] • Rose bengal as a novel organic photocatalyst in an electrochemical sensor for high sensitivity detection of DNA. • The method has good linearity in the range of 1-105 fM in 5 μL of sample with detection limits as low as 0.115 fM. • This Metal-free photoATRP method has great potential in the analysis of biological samples due to its non-pollution, low cost, high specificity and high anti-interference ability. [ABSTRACT FROM AUTHOR] more...

Exosomes, as a kind of tumor biomarker, are often found at elevated levels above normal in the blood of cancer patients, making highly sensitive exosome testing important for monitoring the development and progression of cancer. In this work, an ultra-sensitive and specific fluorescence method for exosome assays was constructed on the basis of atom transfer radical polymerization (ATRP) technique. Firstly, two recognition units, the CD63 aptamer and the EGFR antibody, can specifically bind to exosomes to form a sandwich structure, which endows the proposed sensor with excellent selectivity through two specific recognitions. Secondly, activator regenerated by electron transfer ATRP (ARGET ATRP) polymerization amplification method can introduce a huge amount of the fluorescent monomers into the sensing system, leading to a marked rise in sensitivity. Under optimal experimental conditions, a clear linear relationship between the logarithm of the fluorescence intensity and the concentration of exosomes in the range of 5 × 104 exosomes/mL to 5 × 109 exosomes/mL was obtained. The limit of detection (LOD) was as low as 11,610 exosomes/mL. Furthermore, this sensor exhibited good selectivity and stability, and excellent immunity to interference, providing a new method for the detection of exosomes. The exosome detection strategy used in this system provides a new idea for effective detection of lung cancer at an early stage. [Display omitted] [ABSTRACT FROM AUTHOR] more...

[Display omitted] • RAFT sensor for the amplified detection of cocaine was firstly reported. • Combining RAFT with host–guest interaction for the first time. • This biosensor was successfully achieved in biological samples. In this study, we reported a novel amplification method based on thermally mediated surface − initiated reversible addition − fragmentation chain transfer (SI–RAFT) and host–guest chemistry for electrochemical analysis of cocaine. Firstly, the NH 2 –DNA probes were fixed on the surface of the indium tin oxide (ITO) electrode by addition reaction with 1,4–phenylenediisothiocyanate (PDITC). Then the NH 2 –DNA could specifically recognize target cocaine, and the Ferrocene–DNA (Fc–DNA) probes was connected to the ITO electrode also by specifically binding with cocaine. Next, β–CD–Br 15 was fixed on the surface of the ITO by host–guest interaction between Fc and β–cyclodextrin (β–CD). Finally, ferrocenylmethyl methacrylates (FcMMA) were grown on the surface of ITO via SI–RAFT to form polymer, and then the obtained electrode was measured by square wave voltammetry (SWV). The intensity of signal and the logarithm of cocaine concentration has a good linear relationship in the range of 0.01 ng/mL to 1 µg/mL (R2 = 0.9963), and the detection limit can go down to 0.003 ng/mL (S/N = 3). Moreover, this strategy is appropriate for illegal drugs detection and possess good anti–interference ability for the detection of cocaine in serum samples. [ABSTRACT FROM AUTHOR] more...

Herein we designed a highly sensitive and selective biosensor for methamphetamine (METH) detection based on aptamer recognition probe and atom transfer radical polymerization (ATRP) signal amplification strategy. In this experiment, METH aptamer and its complementary DNA strand were first attached to the electrode surface. In the presence of METH, the prioritized conjugation between METH and the aptamer will take one strand of DNA from the double-stranded DNA, so that the third segment of azide-modified DNA could be successfully modified onto the electrode surface. Through click chemistry and ATRP polymerization, the monomers with ferrocene were polymerized into a long chain, and the signal was amplified, then high-sensitivity detection of METH can be carried out. The result showed that the sensor could detect METH as low as 17 fM, which is about two orders of magnitude lower than that by traditional METH detection methods. Moreover, when different concentrations of METH were added to serum and urine, the recovery rate of the biosensor was as high as 93%. Therefore, using nucleic acid aptamer as capture probe and ATRP as signal amplification strategy can provide a promising application platform for sensitive detection of low concentration toxicants. [Display omitted] • A highly sensitive and selective electrochemical METH biosensor has been described. • The eATRP polymerization combined with click chemistry has been exploited for detecting METH in serum and urine. • The optimized biosensor was capable of detecting 17 fM METH. [ABSTRACT FROM AUTHOR] more...

Ultrasensitive detection of biomarkers at an early stage is generally limited by external influence factors such as high reaction temperature, complex operations, and sophisticated instruments. Here, we circumvent these problems by using nicotinamide adenine dinucleotide (NAD+) to control electroinitiated reversible addition fragmentation chain transfer (electro−RAFT) polymerization for biosensing that enables the detection of a few molecules of target DNA. In this coenzyme−catalyzed electro−RAFT polymerization, numerous ferrocenylmethyl methacrylate (FCMMA) as monomer with electrochemistry signal were linked to the biomarker on Au electrode. Afterwards, a strong oxidation peak appears at the potential of about 0.3 V that represents a typical oxidation potential of FCMMA. The sensitivity of this methodology was presented by detecting DNA from 10−1 to 104 fM concentration and detection limit (LOD) being down to 4.39 aM in 10 μL samples. This is lower by factors than detection limits of most other ultra−sensitive electrochemical DNA assays. [Display omitted] • The nicotinamide adenine dinucleotide (NAD+) is novel to apply in electrochemical biosensing for the detection of DNA. • We detect DNA from 10−1 to 104 fM concentration and the detection limit is as low as 4.39 aM in 10 μL samples. • This platform has the advantages of low background signals, high selectivity, simple preparation and cost effectiveness. [ABSTRACT FROM AUTHOR] more...

The detection of trace tumor-related serum miRNA biomarkers is in great demand for the early diagnosis of cancer. Herein, for the first time, an electrochemical sensing platform based on atom transfer radical polymerization (ATRP) signal amplification strategy for ultrasensitive determination of the breast and prostate cancer marker miRNA-141 has been developed. The hairpin DNAs were immobilized on the benzoic acid modified electrode to capture the target miRNA-141, the recognition of miRNA-141 released thiol groups on the end of probes, followed by the association of ATRP initiators modified gold nanoparticles with thiol groups, and then triggered the polymerization on electrode surface, causing a great number of ferrocene (Fc) signal molecules grafted on the sensor interface. As a result, the electrochemical signal intensity of signal molecule has been greatly increased. The proposed biosensor has a linear range from 10 pM to 10 aM with a detection limit of 3.23 aM for miRNA-141, opening a new and promising path for ultrasensitive analysis of tumor-related miRNAs. [Display omitted] • The AGET ATRP signal amplification strategy was introduced for miRNA-141 detection for the first time. • The proposed signal amplification strategy provides a new way for the analysis of other tumor-related miRNA biomarkers. • Compared with other methods, our signal amplification strategy has higher sensitivity. [ABSTRACT FROM AUTHOR] more...

Cocaine (Coc) is one of the illegal drugs and is harmful to digestive, immune, cardiovascular and urogenital systems. To achieve drug abuse control and legal action, it is essential to develop an effective method for cocaine analysis. In this work, an aptasensor has been developed using atom transfer radical polymerization (ATRP) based on host−guest chemistry for electrochemical analysis of cocaine. The NH 2 −DNA (Apt1) was immobilized on the indium tin oxide (ITO) electrode via addition reaction, and Fc−DNA (Apt2) was introduced to ITO relying on the specific recognition of cocaine. The Apt2 can initiate host−guest chemistry between Apt2 and ATRP initiators (β−CD−Br 15), then the β−CD−Br 15 further triggers ATRP. Moreover, ATRP avoids the sluggish kinetics and poor coupling capability sustained. The result shows a sensitive and selective analysis of cocaine within a linear range from 0.1 ng/mL to 10 μg/mL (R2 = 0.9985), with the detection limit down to 0.0335 ng/mL. Thus, this strategy provides a universal method for the analysis of illegal drugs. [Display omitted] • Firstly, it was reported for cocaine detection based on host−guest chemistry and atom transfer radical polymerization (ATRP). • Ultra-high efficiency was discovered in the synthesized macroinitiator β−CD−Br 15. • This biosensor was successfully achieved in biological samples. [ABSTRACT FROM AUTHOR] more...

Exosomes, as a biomarker with enhancing tumor invasion and spread, play an essential role for lung cancer diagnosis, therapy, and prognosis. In this work, a novel electrochemical sensor was fabricated for detecting exosomes secreted by lung cancer cells based on polysaccharide-initiated ring-opening polymerization (ROP) and click polymerization. First, MPA formed a self-assembled monolayer on the gold electrode surface, and then anti-EGFR was immobilized on the electrode surface by amide bond. Subsequently, a lot of phosphate groups were introduced by the specific recognition between anti-EGFR and exosomes, then sodium alginate grafted Glycidyl propargyl ether (SA- g -GPE) prepared via ROP was attached to the exosomes through PO 4 3-Zr4+-COOH coordination bond. After that, click polymerization was initiated by alkyne groups on the SA- g -GPE polymerization chain to realize highly sensitive detection of A549 exosomes. Under the optimum conditions, the fabricated sensor showed a good linear relationship between the logarithm of exosomes concentration and peak current in the range of 5 × 103 - 5 × 109 particles/mL, and the limit of detection (LOD) was as low as 1.49 × 102 particles/mL. In addition, this method had the advantages of high specificity, anti-interference, high sensitivity, simplicity, rapidity and green economy, which proposed a novel avenue for the detection of exosomes, and also had potential applications in early cancer diagnosis and biomedicine. [Display omitted] • A novel electrochemical sensor is developed for the detection of lung cancer exosomes. • A limit of detection of 1.49 × 102 particles/mL is achieved based on polysaccharide-initiated ROP and click polymerization. • The proposed sensor shows high sensitivity, selectivity, simple , green and economical. • This sensor holds great potential in early diagnosis of lung cancer and biomedical research. [ABSTRACT FROM AUTHOR] more...

• The operation of GO-based biosensor is easy. • Simplify the purification process of the material. • The sensitivity of this biosensor via GO enhancing signal is high. • This method is cost-effective. Atom transfer radical polymerization (ATRP) is an effective polymerization technology, and low ppm ATRP attracts unceasing interest in biological field. In this work, a fast and effective electrochemical biosensor based on graphene oxide (GO) via electrochemically mediated ATRP (eATRP) realized the ultrasensitive detection of lung cancer DNA. Peptide nucleic acid (PNA) was used as capture probes to specifically recognize target DNA, GO was connected to PNA/DNA heteroduplexes via phosphate-Zr4+-carboxylate chemistry to introduce eATRP initiators. Under a potentiostatic condition, eATRP was initiated with the help of reducibility of electrons, and numerous monomers labeled with ferrocene moieties were grafted onto GO. GO was synthesized by modified Hummer's method and was characterized by Fourier transform infra-red spectra (FT-IR) and X-ray diffraction (XRD). The analytical performance of this biosensor was evaluated by square wave voltammetry (SWV) under optimal conditions, its limit of detection (LOD) was 0.213 aM (R2 = 0.994) with a linear range from 1.0 aM to 100 fM. High selectivity of this biosensor indicated a good application potential of genotyping of single nucleotide polymorphisms (SNPs), and simple operation and highly sensitive analytical performance endowed this biosensor a superior application prospect. More importantly, a novel thinking for material application in biological detection was provided in this work. [ABSTRACT FROM AUTHOR] more...

• Dual atom transfer radical polymerization is firstly reported for DNA detection. • Two types of polymerization are used for signal amplification. • The limit of detection of this strategy is greatly improved to 25 amol/L. • This method shows satisfied selectivity and stability for biomolecule detection. Atom transfer radical polymerization as a form of controlled/living radical polymerization is particularly attractive. In this work, dual atom transfer radical polymerization (ATRP) is reported for ultrasensitive DNA detection. Firstly, a peptide nucleic acid (PNA) modified with a thiol group was self-assembled on an electrode surface to capture target DNA (TDNA). The initiator of the first ATRP (ATRP-1), α-bromoisobutyric acid (BIBA), was linked to forming PNA/DNA heteroduplexes via coordination of Zr4+. The polymer chain formed by the monomer of ATRP-1 (2-(2-bromoisobutyryloxy) ethyl methacrylate, BIEM) was also one of initiators of the second ATRP (eATRP-2). The other initiator of eATRP-2 was additional BIBA. ATRP-1 involves activator regeneration by electron transfer (ARGET) ATRP, regulated via excess reducing agent. eATRP-2 is electrochemically mediated ATRP which can control the polymerization via an appropriate applied potential. Compared with one ATRP, more monomers of eATRP-2 modified with ferrocene are attached to electrode surface. Under optimal conditions, this dual ATRP strategy provides a low limit of detection (25 aM, ~150 molecules) with satisfactory selectivity and stability. Importantly, this strategy presents a useful prospect for the field of biomolecule detection. [ABSTRACT FROM AUTHOR] more...