A sensitive and label-free electrochemical microRNA biosensor based on Polyamidoamine Dendrimer functionalized Polypyrrole nanowires hybrid

Nanostructured conductive polymers: synthesis and application in biomedicine

Conductive polymers (CPs), distinguished by their sp2-hybridized carbon backbone, offer remarkable electrical conductivity while maintaining the advantageous mechanical flexibility and processing characteristics typical of organic polymers. Compared to their bulk counterparts, nanostructured CPs exhibit unique physicochemical properties, such as large surface areas and shortened charge/mass transport pathways, making them promising candidates for various applications. This mini review explores various synthesis methodologies for nanostructured CPs, including electrospinning, hard templating, and soft templating techniques, while elucidating their advantages and disadvantages. Additionally, the burgeoning biomedical applications of nanostructured CPs are highlighted, including drug delivery, neural electrodes and interfaces, nerve regeneration, and biosensing, demonstrating their potential to significantly advance contemporary biomedical science.

Vertical growth of rhenium disulfide on rGO empowers multi-signal amplification for ultrasensitive MiRNA-21 detection

Unique rhenium disulfide/reduced graphene oxide (ReS2/rGO) nanoframeworks were synthesized with a hierarchical layered and porous structure for the ultrasensitive electrochemical detection of microRNA-21 (miRNA-21) by empowering multi-signal amplification strategy of catalytic hairpin self-assembly-hybridization chain reaction (CHA-HCR). The layered and porous nanostructures endowed ReS2/rGO with a larger specific surface area and more active sites through connecting vertical ReS2 with rGO which was preferable for promoting the electron transfer over electrode surface because of a conductive network. This nanoframework facilitated the loading of adequate gold nanoparticles to fix the capture probe via Au-S bond. In the presence of the target miRNA-21, the CHA-HCR double amplification reaction could be triggered to generate a long double strand with methylene blue (MB) embedded inside. The electrochemical sensing platform was thus empowered by the unique ReS2/rGO nanoframeworks to detect miRNA-21 in the range 1 fM ~ 100 pM with the remarkably enhanced sensitivity through detecting the significantly amplified signal from the REDOX reaction of MB inside the long chain. The verification of the miRNA-21 detection in real blood samples further proved the great potential of this new method with the limit of detection reduced down to 0.057 fM and opens a new window for ReS2 in developing sensitive biosensors for early clinical cancer diagnosis.

Development of bismuth sulfide nanorods and polyamidoamine dendrimer on reduced graphene oxide as electrode nanomaterials for electrochemical determination of salbutamol

Dendrimers, a new class of nanomaterials, are receiving more attention in various fields. In this study, by combining the advantages of polyamidoamine (PAMAM) dendrimer with reduced graphene oxide (rGO) and bismuth sulfide (Bi₂S₃), we came to design a new composite and its application for electrochemical sensors was investigated for the first time. As a new approach in the preparation of the composite, PAMAM was used for the first time to increase the surface of Bi₂S₃ with rGO, which ultimately led to an increase in the active surface area of the sensor (5 times compared to the bare electrode). For the first time, we used the sonochemical method for interaction between PAMAM with Bi₂S₃ and rGO, which was a simpler and faster method to prepare the composite. The purposeful design of the composite was done by using the experimental design method to obtain the optimum composition of components. The new nanocomposite was successfully applied for simple and sensitive electrochemical sensing of salbutamol for controlling the health of food. Salbutamol is used as a prohibited additive in animal and poultry feed. The sensor has good sensitivity (35 times increase compared to the bare electrode) and a low detection limit (1.62 nmol/L). Moreover, it has acceptable selectivity, good repeatability (1.52-3.50%), good reproducibility (1.88%), and satisfactory accuracy (recoveries: 84.6-97.8%). An outstanding feature of the sensor is its broad linear range (5.00-6.00 × 10² nmol/L). This sensor is well suited for the determination of salbutamol in milk, sausage, and livestock and poultry feed samples.

Application of Polypyrrole-Based Electrochemical Biosensor for the Early Diagnosis of Colorectal Cancer

Although colorectal cancer (CRC) is easy to treat surgically and can be combined with postoperative chemotherapy, its five-year survival rate is still not optimistic. Therefore, developing sensitive, efficient, and compliant detection technology is essential to diagnose CRC at an early stage, providing more opportunities for effective treatment and intervention. Currently, the widely used clinical CRC detection methods include endoscopy, stool examination, imaging modalities, and tumor biomarker detection; among them, blood biomarkers, a noninvasive strategy for CRC screening, have shown significant potential for early diagnosis, prediction, prognosis, and staging of cancer. As shown by recent studies, electrochemical biosensors have attracted extensive attention for the detection of blood biomarkers because of their advantages of being cost-effective and having sound sensitivity, good versatility, high selectivity, and a fast response. Among these, nano-conductive polymer materials, especially the conductive polymer polypyrrole (PPy), have been broadly applied to improve sensing performance due to their excellent electrical properties and the flexibility of their surface properties, as well as their easy preparation and functionalization and good biocompatibility. This review mainly discusses the characteristics of PPy-based biosensors, their synthetic methods, and their application for the detection of CRC biomarkers. Finally, the opportunities and challenges related to the use of PPy-based sensors for diagnosing CRC are also discussed.

Assessing Meat Freshness via Nanotechnology Biosensors: Is the World Prepared for Lightning-Fast Pace Methods?

In the rapidly evolving field of food science, nanotechnology-based biosensors are one of the most intriguing techniques for tracking meat freshness. Purine derivatives, especially hypoxanthine and xanthine, are important signs of food going bad, especially in meat and meat products. This article compares the analytical performance parameters of traditional biosensor techniques and nanotechnology-based biosensor techniques that can be used to find purine derivatives in meat samples. In the introduction, we discussed the significance of purine metabolisms as analytes in the field of food science. Traditional methods of analysis and biosensors based on nanotechnology were also briefly explained. A comprehensive section of conventional and nanotechnology-based biosensing techniques is covered in detail, along with their analytical performance parameters (selectivity, sensitivity, linearity, and detection limit) in meat samples. Furthermore, the comparison of the methods above was thoroughly explained. In the last part, the pros and cons of the methods and the future of the nanotechnology-based biosensors that have been created are discussed.

Combining bioinspired nanochannels with ferrocene doped MoS2 nanoplates: Application to ratiometric electrochemical detection of let-7a

Sensitive and accurate detection of tumor suppressor genes is vastly important to the related therapeutic research. Herein, a ratiometric electrochemical method for let-7a detection was established by integrating a ferrocene (Fc) doped MoS₂ nanoplates modified electrode into the nanochannels-based biosensing platform. The ratiometric signal was developed by the redox current of methylene blue (MB) which reflects the target recognition occurred into the nanochannels and the redox current of Fc which corrects the slight signal deviation caused by some analyte-independent factors. And thus, the ratio of peak current of MB and Fc (I_MB/I_Fc) measured at differential pulse voltammogram varied precisely with the increment of the concentration of let-7a incubated in the bioinspired nanochannels. The strategy of spherical DNAzyme induced deposition in nanochannels was utilized to further amplify the signal. Under optimal conditions, a wide linear dynamic range of 50 aM to 10 pM spanning five orders of magnitude was obtained. The developed electrochemical method, with attomole level of detection limit, was successfully applied to the determination of let-7a in human serum and tumor cells. The study not only offers a new route for reliable nucleic acid detection, but also provides an excellent opportunity to extend the application of the two-dimensional transition-metal dichalcogenides.

Numerical simulation of optical refractometric sensing of multiple disease markers based on lab-in-a-fiber

A multi-parameter optical refractometric sensor based on lab-in-a-fiber is proposed and its sensing properties have been investigated. Based on the particular three suspended-core fiber, the sensor has three channels for liquid circulation and three suspended cores for detection. The multiple disease markers can be detected by coating the specific bio-recognition layer on the surface of three channels. The bio-recognition layer thickness, representing the concentration of the disease markers, can then be measured by the wavelength of fiber Bragg grating inscribed in each suspended core. Owing to the triple symmetry of the fiber, the sensitivity of each core is similar. The simulation results show that the grating wavelength linearly changes with the bio-recognition layer thickness variation. Through the sensitivity matrix, the sensitivity of the sensor is 0.362 nm/nm and the sensing accuracy is ± 1 nm.

The Bioanalytical and Biomedical Applications of Polymer Modified Substrates

Polymers with different structures and morphology have been extensively used to construct functionalized surfaces for a wide range of applications because the physicochemical properties of polymers can be finely adjusted by their molecular weights, polydispersity and configurations, as well as the chemical structures and natures of monomers. In particular, the specific functions of polymers can be easily achieved at post-synthesis by the attachment of different kinds of active molecules such as recognition ligand, peptides, aptamers and antibodies. In this review, the recent advances in the bioanalytical and biomedical applications of polymer modified substrates were summarized with subsections on functionalization using branched polymers, polymer brushes and polymer hydrogels. The review focuses on their applications as biosensors with excellent analytical performance and/or as nonfouling surfaces with efficient antibacterial activity. Finally, we discuss the perspectives and future directions of polymer modified substrates in the development of biodevices for the diagnosis, treatment and prevention of diseases.

Cyclodextrin-dendrimers nanocomposites functionalized high performance liquid chromatography stationary phase for efficient separation of aromatic compounds

In this work, novel cyclodextrin-dendrimers nanocomposites functionalized high performance liquid chromatography stationary phases were developed for efficient separation of aromatic compounds. β-cyclodextrin was grafted onto the surface of silica gel matrix with poly (amidoamine) dendrimers as spacers. Scanning electron microscope, fourier transform infrared spectroscopy, element analysis and Brunner-Emmet-Teller measurement proved the successful grafting of cyclodextrin-dendrimers nanocomposites. The obtained stationary phases showed satisfactory separation effects for alkylbenzenes and benzenesulfonic acid substituents in reverse phase liquid chromatography mode. Weak hydrophilic and ion exchange interactions were also confirmed at the same time. Meanwhile, the effects of dendrimers and cyclodextrin on the chromatography performance were discussed. Separation mechanism of the stationary phases were verified by two-dimensional nuclear magnetic resonance technology, and the result implied that the proposed cyclodextrin-dendrimers nanocomposites functionalized stationary phases have significant prospects for separation and determination of more aromatic compounds in future.

Electrochemical DNA Sensor Based on Acridine Yellow Adsorbed on Glassy Carbon Electrode

Electrochemical DNA sensors offer unique opportunities for the sensitive detection of specific DNA interactions. In this work, a voltametric DNA sensor is proposed on the base of glassy carbon electrode modified with carbon black, adsorbed acridine yellow and DNA for highly sensitive determination of doxorubicin antitumor drug. The signal recorded by cyclic voltammetry was attributed to irreversible oxidation of the dye. Its value was altered by aggregation of the hydrophobic dye molecules on the carbon black particles. DNA molecules promote disaggregation of the dye and increased the signal. This effect was partially suppressed by doxorubicin compensate for the charge of DNA in the intercalation. Sensitivity of the signal toward DNA and doxorubicin was additionally increased by treatment of the layer with dimethylformamide. In optimal conditions, the linear range of doxorubicin concentrations determined was 0.1 pM–1.0 nM, and the detection limit was 0.07 pM. No influence of sulfonamide medicines and plasma electrolytes on the doxorubicin determination was shown. The DNA sensor was tested on two medications (doxorubicin-TEVA and doxorubicin-LANS) and showed recoveries of 102–105%. The DNA sensor developed can find applications in the determination of drug residues in blood and for the pharmacokinetics studies.