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The early diagnosis of major diseases, such as malignant tumors, has always been an important field of research. Through screening, early detection of such diseases, and timely and effective treatment can significantly improve the survival rate of patients and reduce medical costs. Therefore, the development of a simple detection method with high sensitivity and strong specificity, and that is low cost is of great significance for the diagnosis and prognosis of the disease. Electrochemical DNA biosensing analysis is a technology based on Watson Crick base complementary pairing, which uses the capture probe of a known sequence to specifically recognize the target DNA and detect its concentration. Because of its advantages of low cost, simple operation, portability, and easy miniaturization, it has been widely researched and has become a cutting‐edge topic in the field of biochemical analysis and precision medicine. However, the existing methods for electrochemical DNA biosensing analysis have some shortcomings, such as poor stability and specificity of capture probes, insufficient detection sensitivity, and long detection cycles. In this review, we focus on improving the sensitivity and practicability of electrochemical DNA biosensing analysis methods and summarize a series of research work carried out by using electrically neutral peptide nucleic acid as an immobilized capture probe. [ABSTRACT FROM AUTHOR]

[Display omitted] • A DNA sensor based on atom transfer radical polymerization (ATRP) was designed. • Photo-ATRP based on catalyst 10-phenylphenothiazine was first applied in biosensor. • The biosensor has highly sensitive to t-DNA with a detection limit of 79 aM. • The biosensor was successfully used for detection of DNA in biological samples. The development of ultrasensitive deoxyribonucleic acid (DNA) sensors related to the disease is of great significance for early diagnosis and prevention of the disease. Here, an ultrasensitive DNA sensor based on the photocatalytic atom transfer radical polymerization (photo-ATRP) strategy was prepared. In this strategy, the target DNA was specifically recognized by sulfhydryl-modified peptide nucleic acid (PNA), and α-bromophenylacetic acid (BPAA) was grafted onto the DNA via phosphate-Zr(IV)-carboxylate. In the presence of photocatalyst 10-phenylphenothiazine (PTH), α-Br was reduced under 365 nm UV light to generate active radicals, and the polymer chain containing electrochemical signaling molecule (ferrocene) was introduced to the electrode surface by mediated ATRP. Finally, the peak current value was measured by square wave voltammetry (SWV) and the concentration of DNA was evaluated. The biosensor was constructed based on a green strategy for ATRP reaction without using a heavy metal catalyst (metal-free), thus reducing the pollution of the environment. Moreover, under optimal conditions, the relationship between the DNA sensor and the target was linear in the concentration range of 0.1 fM ∼ 10 pM, and the limit of detection was 79 aM. The sensor has the advantages of high sensitivity, interference-free and good stability, which indicates that it has great practical application potential in the field of life science and medical research. [ABSTRACT FROM AUTHOR]

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]

[Display omitted] • A highly selective and ultrasensitive DNA detection method was developed by utilizing target cycle and ATRP. • The optimized biosensor was capable of detecting 1.954 aM target DNA (12 molecules DNA can be detected in a 10 μL system). • This signal amplification strategy can be applied for the detection of protein and other biological molecular. We propose a novel electrochemical biosensor platform with triple helix structure as switch, Exonuclease III (Exo III)-mediated target cycle at 2-D level and electrochemical-mediated atom transfer radical polymerization (ATRP) at 3-D level as double signal amplification strategy for nucleic acid detection with ultra-sensitivity and high-selectivity. In this strategy, triple-helical DNA modified with N 3 was first constructed on the gold electrode (AuE) surface. Exo III mediated target cycle was then triggered in the presence of Target DNA. N 3 was released and exposed on the AuE surface, owing to the triple helix structure was destroyed in this process. propargyl-2-bromoisobutyrate (PBIB), the initiator of ATRP, was then introduced to the biosensor surface via click chemistry. Finally, electrochemically mediated ATRP polymerizes a large amount of electroactive monomer, ferrocene methacrylate (FMMA), onto the AuE surface. The target circulates to make target DNA reused at the 2-D level, and ATRP polymerizes a large number of electrochemical signal molecules at the 3-D level, making the biosensor detection limit as low as 1.954 aM. Moreover, the linear range of target DNA detection reaches 7 orders of magnitude (10 aM-10 fM, R2 = 0.993). In addition, the biosensor shows excellent anti-interference ability when analyzing DNA in serum samples. In short, the preparation method is rapid, simple, easy to operate, and has potential applications in biological analysis. [ABSTRACT FROM AUTHOR]

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]

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. [Display omitted] • A miRNA-21 sensor based on atom transfer radical polymerization was designed. • Photo-ATRP based on catalyst fluorescein was first applied in biosensor. • The biosensor has highly sensitive to miRNA-21 with a detection limit of 1.35 fM. • The biosensor has good anti-interference ability in normal human serum. [ABSTRACT FROM AUTHOR]

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]

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]