Fluorescence Sensing of Eclampsia Biomarkers via the Immunosorbent Atom Transfer Radical Polymerization Assay.

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.

Controllable radical polymerization of TEMPO redox for stable and sensitive enzyme electrode interface.

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.

An electrochemical biosensor for the amplification of thrombin activity by perylene-mediated photoinitiated polymerization.

BACKGROUND: 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. RESULTS: 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 âˆ¼ 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. SIGNIFICANCE: 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.

Application potential of senolytics in clinical treatment.

Of the factors studied in individual ageing, the accumulation of senescent cells has been considered as an essential cause of organ degeneration to eventually initiate age-related diseases. Cellular senescence is attributed to the accumulation of damage for an inducement in the activation of cell cycle inhibitory pathways, resulting the cell permanently withdraw from the cell proliferation cycle. Further, senescent cells will activate the inflammatory factor secretion pathway to promote the development of various age-related diseases. Senolytics, a small molecule compound, can delay disease development and extend mammalian lifespan. The evidence from multiple trials shows that the targeted killing of senescent cells has a significant clinical application for the treatment of age-related diseases. In addition, senolytics are also significant for the development of ageing research in solid organ transplantation, which can fully develop the potential of elderly organs and reduce the age gap between demand and supply. We conclude that the main characteristics of cellular senescence, the anti-ageing drug senolytics in the treatment of chronic diseases and organ transplantation, and the latest clinical progress of related researches in order to provide a theoretical basis for the prevention and treatment of ageing and related diseases.

Ultrasensitive detection of miRNA-21 by click chemistry and fluorescein-mediated photo-ATRP signal amplification.

The development of a convenient and efficient assay using miRNA-21 as a lung cancer marker is of great importance for the early prevention of cancer. Herein, an electrochemical biosensor for the detection of miRNA-21 was successfully fabricated under blue light excitation using click chemistry and photocatalytic atom transfer radical polymerization (photo-ATRP). By using hairpin DNA as a recognition probe, the electrochemical sensor deposits numerous electroactive monomers (ferrocenylmethyl methacrylate) on the electrode surface under the reaction of photocatalyst (fluorescein) and pentamethyldiethylenetriamine, thereby achieving signal amplification. This biosensor is sensitive, precise and selective for miRNA-21, and is highly specific for RNAs with different base mismatches. Under optimal conditions, the biosensor showed a linear relationship in the range of 10 fM ∼1 nM (R2 = 0.995), with a detection limit of 1.35 fM. Furthermore, the biosensor exhibits anti-interference performance when analyzing RNAs in serum samples. The biosensor is based on green chemistry and has the advantages of low cost, specificity and anti-interference ability, providing economic benefits while achieving detection objectives, which makes it highly promising for the analysis of complex samples.

Solvent-directed multiple correspondence fluorescent probe for highly selective and sensitive detection of Cu2+ and Mg2.

A solvent-directed, new Schiff base multiple correspondence fluorescent probe, (E)-2-(2-hydroxybenzylidene) hydrazine-1-carboxamid (L), was synthesized for selective sensing of Cu2+ and Mg2+ ions. L showed excellent selectivity and high sensitivity toward Cu2+ in "turn off" mode with a detection limit of 40.5 nM in 10 mM, pH = 7.0 PBS buffer. Contrary to that, when acetonitrile was used as the solvent, L exhibited highly selective and sensitive fluorescence sensing ability for Mg2+ in "turn on" mode with a detection limit of 9.5 nM. L can coordinate to Cu2+ and Mg2+ in a 1:1 molar ratio, respectively, evidenced by Job's plot analysis. Their binding modes were investigated by NMR, IR and XPS spectroscopies. Moreover, the satisfied results were obtained when L was used to detect Cu2+ and Mg2+ in real water samples.

Mn-MOF catalyzed multi-site atom transfer radical polymerization electrochemical sensing of miRNA-21.

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@ß-CD-Br15 and permit the initiator to be immobilized on the electrode surface. Accordingly, ß-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 ß-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.

Cyanocobalamin (VB12) Bionic Enzyme-Assisted Photocatalytic Chain-Growth Polymerization for Detection of Lung Cancer Biomarkers.

Cobalt-mediated radical polymerization is noted for its great level of control over the polymerization of acrylic and vinyl esters monomers, even at high molar mass. Vitamin B12, a natural bionic enzyme cobalt complex, involves the conversion of organic halides to olefins through chain-growth polymerization. In this work, the notion of R-Co(III) free radical persistent free radical effect and vitamin B12 circulation were first reported for the perception of ultralow abundance of microRNA-21, a lung cancer biomarker. Indeed, most Co-containing catalytic reactions can occur under mild conditions due to their minimal bond dissociation of the C-Co bond, with blue light irradiation. Based on the intrinsic stability of the vitamin B12 framework and recycling of the catalyst, it is evident that this natural catalytic scheme has potential applications in medicinal chemistry and biomaterials. In addition, this strategy, combined with highly specific recognition probes and vitamin B12 circulation-mediated chain-growth polymerization, has a detection limit as low as 910 aM. Furthermore, it is sensitive for sensing in serum samples containing biomarkers and shows great potential for RNA selection and amplification sensing in clinical samples.

Ultrasensitive miRNA-21 Biosensor Based on Zn(TCPP) PET-RAFT Polymerization Signal Amplification and Multiple Logic Gate Molecular Recognition.

Quantitative measurement of microRNAs (miRNAs) is extremely important in plenty of biomedical applications especially cancer diagnosis but remains a great challenge. In this work, we developed a logic gate recognition biosensing platform based on the "trinity" molecular recognition mode for quantifying miRNAs with a detection limit of 4.48 aM, along with a linear range from 0.1 nM to 10 aM under optimal experimental conditions. In order to obtain excellent detection performance, we adopted a Zn(TCPP) photocatalytic electron transfer reversible addition-fragmentation chain transfer (PET-RAFT) polymerization signal amplification strategy. The light-induced PET-RAFT has developed green applications of free radical polymerization in the field of biosensors. This is the first report on the preparation of signal amplification biosensors using PET-RAFT for tumor marker detection. With the outstanding detection performance, we can apply the sensor system to the early screening of lung cancer patients.

A dichromatic plasmonic ELISA CD81 protein sensor for ultrasensitive detection of preeclampsia.

Preeclampsia (PE) seriously affects pregnant women and fetuses' health and causes maternal near-misses. CD81 has been confirmed to be a novel PE biomarker with great potential. Herein, a hypersensitive dichromatic biosensor based on the plasmonic enzyme-linked immunosorbent assay (plasmonic ELISA) is proposed initially for the application of CD81 in early screening for PE. In this work, a novel chromogenic substrate [(HAuCl4)-(N-methylpyrrolidone)-(Na3C6H5O7)] is designed based on the H2O2 dual catalysis reduction pathway of Au ions. The two reduction pathways of Au ions are controlled by H2O2 which ensures that the synthesis and growth of AuNPs are sensitive to H2O2. The amount of H2O2 correlates with the concentration of CD81 and directs the production of different-sized AuNPs in this sensor. Blue solutions are generated when analytes are present. When analytes are absent, solutions turn red. Therefore, due to different absorption peaks in red and blue, bimodal detection can be performed, and then two detection signals can be generated, one on signal at 550 nm and another off signal at 600 nm. This method exhibits a linear response to the logarithmic CD81 concentrations in the range of 0.1-1000 pg mL-1 with detection limits of 86 fg mL-1 and 152 fg mL-1 at two wavelengths. The false positive rate is low due to the nonspecific coloration caused by serum, which produces a more intense color contrast. The results indicate that the proposed dichromatic sensor could be used as a visual sensing platform for the direct detection of CD81 in biological samples and demonstrate its potential in preeclampsia diagnosis.

A novel fluorescence sensor for uranyl ion detection based on a dansyl-modified peptide.

It is of great significance to sensitively and selectively detect uranyl ion (UO22+) in environmental and biological samples due to the high risks of UO22+ to human health. However, such suitable sensors are still scarce. A novel fluorescence sensor based on a dansyl-modified peptide, Dansyl-Glu-Glu-Pro-Glu-Trp-COOH (D-P5), was efficiently synthesized by Fmoc solid phase peptide synthesis. As the first linear peptide-based fluorescence sensor for UO22+, D-P5 exhibited high selectivity and sensitivity to UO22+ over 27 metal ions (UO22+, Cr3+, Cu2+, Ba2+, Hg2+, Pb2+, Co2+, Ag+, Fe3+, Ca2+, K+, Mg2+, Mn2+, Na+, Ni2+, Cd2+, Zn2+, Al3+, Dy3+, Er3+, Gd2+, Ho3+, La3+, Lu3+, Pr3+, Sm3+, Tm3+) by a turn-off fluorescence response in 10 mM HEPES buffer (pH 6.3). The effects of anions such as S2-, NO3-, SO42- CO32-, HCOO-, antioxidant ascorbic acid and 4-nitrophenyl acetate on the selectivity for UO22+ detection were also studies. D-P5 sensor could be used for detecting UO22+ in a good linear relationship with concentration in the range of 0-8.0 µM with a low limit of detection of 83.2 nM. Furthermore, the interaction of the sensor with UO22+ was characterized by ESI-MS, IR, XPS and ITC measurements. The 1:1 binding stoichiometry between the sensor and UO22+ was measured by the job's plot and further verified by ESI-MS. The binding constant of the sensor with UO22+ was calculated to be 9.8 × 104 M-1 by modified Benesi-Hildebrand equation. ITC results showed that theΔHθ andΔSθ for the interaction of D-P5 with UO22+ were -(7.167 ± 1.25) kJ·mol-1 and 66.5 J·mol-1·K-1, respectively. Time-resolved fluorescence spectroscopy indicated that the mechanism of fluorescence quenching of D-P5 by UO22+ ion was static quenching process. In addition, this sensor displayed a good practicality for UO22+ detection in lake water sample without tedious sample pretreatment.

Ferritin-Enhanced Direct MicroRNA Detection via Controlled Radical Polymerization.

Accurate quantitative detection of tracing nucleic acids remains a great challenge in cancer genetic testing. It is crucial to propose a low-cost and highly sensitive direct gene detection method for cancer prevention and treatment. Herein, this work reports an ultrasensitive biosensor via a ferritin-enhanced atom-transfer radical polymerization (Ft-ATRP) process. Intriguingly, microRNA-21, an early marker of lung cancer, can be detected without being transcribed in advance by an innovative signal amplification strategy using ferritin-mediated aggregation of hydrophilic nitroxide radical monomers as an electrochemical biosensor. The sensor uses peptide nucleic acid probes modified on a gold electrode to accurately bind the target lung cancer marker in the sample, and then ferritin, which is naturally present in human blood, induces Ft-ATRP on the electrode surface under mild conditions. Many of 4-methacryloyloxy-2,2,6,6-tetramethylpiperidine 1-oxyl free radical (MATMP) monomers with electrochemical signals are combined into polymeric chains to be modified on target assays. The limit of detection (LOD) of microRNA-21 is as low as 6.03 fM, and the detection concentration ranges from 0.01 to 100 pM (R2 = 0.994). The RNA biosensor can realize great performance analysis of complicated samples in simple operation, in addition, the detection process used by the catalyst, polymers containing electrochemical signals, and the electrolyte solution all have good water solubility. The superior performance of the RNA biosensor demonstrates its potential to screen and identify lung cancer in target patients.

Rose bengal-mediated photoinduced atom transfer radical polymerization for high sensitivity detection of target DNA.

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, ß-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.

Sensitive electrochemical detection of A549 exosomes based on DNA/ferrocene-modified single-walled carbon nanotube complex.

Exosome is an emerging tumor marker, whose concentration level can reflect the occurrence and development of tumors. The development of rapid and sensitive exosome detection platform is of great significance for early warning of cancer occurrence. Here, a strategy for electrochemical detection of A549-cell-derived exosomes was established based on DNA/ferrocene-modified single-walled carbon nanotube complex (DNA/SWCNT-Fc). DNA/SWCNT-Fc complexes function as a signal amplification platform to promote electron transfer between electrochemical signal molecules and electrodes, thereby improving sensitivity. At the same time, the exosomes can be attached to DNA/SWCNT-Fc nanocomposites via the established PO43--Ti4+-PO43- method. Moreover, the application of EGFR antibody, which can specifically capture A549 exosomes, could improve the accuracy of this sensing system. Under optimal experimental conditions, the biosensor showed good linear relationship between the peak current and the logarithm of exosomes concentration from 4.66 × 106 to 9.32 × 109 exosomes/mL with a detection limit of 9.38 × 104 exosomes/mL. Furthermore, this strategy provides high selectivity for exosomes of different cancer cells, which can be applied to the detection of exosomes in serum samples. Thus, owing to its advantages of high sensitivity and good selectivity, this method provides a diversified platform for exosomes identification and has great potential in early diagnosis and biomedical applications.

A novel colorimetric detection of glutathione based on stable free radical TEMPO oxidation of 3,3',5,5'-tetramethylbenzizine (TMB) via Copper(II) acetylacetonate catalysis.

In this work, a new colorimetric method for the determination of Glutathione (GSH) on the basis of stable free radical 2,2,6,6 - tetramethylpiperidine - 1 - oxyl (TEMPO) oxidation of 3,3',5,5'-tetramethylbenzizine (TMB) via copper(II) acetylacetonate (Cu(acac)2) catalysis was proposed. TEMPO was catalyzed by Cu(acac)2 to produce TEMPO+, then TEMPO+ oxidized TMB to produce oxidized TMB (ox - TMB). The resulting ox - TMB showed blue and possessed a distinct absorption peak about 650 nm. Whereas, GSH prohibited the generation of ox - TMB through inhibiting TMB oxidation. As compared to the case that GSH was absent, significantly enhanced absorption was determined, and was proportional to GSH amount. On this basis, a qualitative and quantitative detection method of GSH with the naked eye and the microplate reader was achieved. The developed TEMPO - based method achieved GSH biosensing with improved sensitivity in a good specificity - manner. The limit of detection (LOD) was 90 µM via naked eye, and the microplate reader was 4.71 µM. And the stable free radical TEMPO possessed higher stability and lower toxicity than traditional oxidant of H2O2. Moreover, this TEMPO - based method achieved good results in the detection of GSH in human serums.

Stable nitronyl nitroxide monoradical MATMP as novel monomer of reversible addition fragmentation chain transfer (RAFT) polymerization for ultrasensitive DNA detection.

In this work, it came up a hydrophilic and stable nitronyl nitroxide monoradical 4-methacryloyloxy-2,2,6,6-tetramethylpiperidine 1-oxyl freeradical (MATMP) as new monomer of polymerization for DNA detection. The detection limit was over 1,000,000 times lower than 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) derivatives as electrochemical labels alone. Within this approach, a single biomolecule can be converted into the strong electrochemical signal, therefore lung cancer DNA can be detected at low concentration. For the first step, the HS-PNA probe was fixed on the surface of the Au electrode. After the target DNA was captured by complementary base pairing, 4-cyano-4-(phenylcarbonothioylthio) pentanoic acid (CPAD), chain transfer agent of RAFT polymerization, was bonded to target DNA as reaction via coordination bond of Zr4+. Electroactive polymers had grown by means of surface initiated thermally RAFT polymerization with MATMP as monomer. MATMP polymer significantly improves the electrochemical signal. This method can detect DNA from 0.01 fM to 10 pM, and detection limit is 1.51 aM. The sensitivity of this method is greater than that in most other reported signal amplification strategies of DNA biosensor, which indicates that it is appropriate for single nucleotide polymorphism analysis and will broaden prospects for biological molecules detection application.

Hemoglobin-catalyzed atom transfer radical polymerization for ultrasensitive electrochemical DNA detection.

The use of hemoglobin (Hb) to drive atom transfer radical polymerization (ATRP) process (Hb-ATRP) for detection of lung cancer related nucleic acid is firstly reported. Hb does not need to be treated prior to using indicating the potential for synthetic engineering in complex biological microenvironments without the need for in vitro techniques. Here, we report a new signal amplification strategy using Hb-mediated graft of nitronyl niroxide monoradical polymers as a signal-on electrochemical biosensor for ultralow level DNA highly selective detection. Building DNA biosensors includes: (i) the fixation of peptide nucleic acid (PNA) probe (no phosphate group) via the 5' terminus-SH; (ii) the modification of transition metal; (iii) Site-specific markers of Hb-ATRP promoter, and (iv) the grafting of polymers with electrochemical signal by Hb-ATRP process. Through the Hb-ATRP process of nitronyl nitroxide monoradical (TEMPO), the presence of a small amount of DNA can eventually result in calling a certain number of TEMPO redox tags. Obviously, the Hb-ATRP is a method of easy source of raw materials, simple operation and no need for complex equipment. The constructed biosensor, as expected, is highly selective and sensitive to target DNA. The detection limit can be calculated as 15.96 fM under optimal conditions. The excellent performance also shows that the constructed DNA biosensor is suitable for DNA screening and DNA concentration determination in complex sample matrix.

Fluorescent assay of alkaline phosphatase activity via atom transfer radical polymerization.

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.

Sensitive electrochemiluminescence analysis of lung cancer marker miRNA-21 based on RAFT signal amplification.

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.

High sensitive electrochemical methamphetamine detection in serum and urine via atom transfer radical polymerization signal amplification.

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.