Biosensors and Bioelectronics: X最新文献

This paper introduces a unique multimode, multichannel piezoelectric vibration sensor for the next-generation fully implantable cochlear implant (FICI) systems. The sensor, which can be implanted on the middle ear chain to collect and filter the ambient sound in eight frequency bands, comprises an array of 4 M-shape multimode and 11 single cantilevers. Finite element (FE) analysis indicates a 2.05-fold improvement in capturing frequency information for the multimodal sensor compared to its single-mode counterpart. Under an acoustic excitation at 100 dB SPL, the sensor, mounted on an artificial tympanic membrane, yielded a peak output voltage of 546.16 mVpp and a peak sensitivity of 285.28 mVpp/Pa at 1613 Hz. The extrapolated acoustic results indicated a dynamic frequency range between 300 Hz and 6 kHz, even at 30 dB SPL. Furthermore, a lightweight titanium coupler, employing a two-sided clipping structure with a maximum wall thickness of 70 μm, is micromachined for surgical attachment of the transducer to the middle ear chain. A commercial accelerometer, implanted on the incus short process (SP) of a cadaver using the titanium coupler, successfully recorded 0.1 g for 100 dB SPL at 500 Hz, revealing the potential feasibility of the coupler for vibration sensor implantation. Moreover, the presented anatomically accurate FE model of the middle ear, exhibiting a high correlation coefficient (R²) of 0.97 with the cadaveric experiment, suggests an efficient numerical approach for evaluating the implantation of middle ear prostheses. In this regard, the study holds great promise for clinical application in the field of implantable hearing aids.

Prostate cancer (PCa) appears among the most frequently diagnosed types of malignancies in males. Because of the high demand and increasing detection rate of early PCa, alongside the specificity limitations of the gold standard clinical tools available for the diagnosis and prognosis of prostate cancer, there is an urgent need for more reliable PCa markers and highly sensitive diagnostic tools to avoid under-treatment and over-diagnosis. PCA3, or prostate cancer antigen 3, is a potential prostate cancer biomarker that is more specific and useful for preventing unnecessary repeat biopsies, particularly in men with persistently high prostate-specific antigen indices after a negative biopsy. Additionally, an electrochemically based biosensor would prove to be a powerful diagnostic tool for PCA3 detection in urine because of its simplicity, sensitivity, and cost-effectiveness, in contrast to the more traditional PCa diagnostics that depend on blood testing. This paper aimed to design a novel and simple electrochemical impedimetric biosensor based on a label-free RNA-aptamer (CG3-PCA3) as the molecular recognition element for detecting PCA3. The proposed aptasensor for the detection of PCA3 has been developed using a screen-printed carbon electrode (SPCE) modified by gold nanoparticles (AuNPs), further improving sensitivity and allowing the immobilisation of thiolate aptamers on its surface. The findings presented here demonstrated a high sensitivity to PCA3, with a detection limit of 20 fM in artificial urine and 1 fM in buffer. These results indicate that the PCA3 aptasensor could be a promising tool for routine PCa diagnosis due to its high sensitivity and cost-effectiveness.

Nucleic acid amplification tests (NATs), such as genetic tests using polymerase chain reaction (PCR), are sensitive methods for detecting pathogens and food contamination. The rapid, easy, and inexpensive detection of amplicons, DNA, or RNA is key to realizing on-site NATs. We have previously developed a novel amplicon detection method using magnetic microbeads based on the hydrophobicity of DNA in deionized water. In this study, we aimed to expand the method for the detection of multiplex DNA amplicons. Tagged primers and probes for selective attachment were used to detect amplicons from two strawberry pathogens. The amplicon-labeled magnetic microbeads were placed in the round-bottom well of a hydrophilic glass substrate. The attachment of amplicons to the magnetic microbeads changed their surface from hydrophilic to hydrophobic. The magnetized microbeads concentrated at the bottom when the substrate was placed on a permanent magnet, and the concentrated microbeads were easily recognizable by the naked eye. Microbeads without amplicons were adsorbed over a broad area of the bottom of the glass well owing to their hydrophilicity. The appropriate tag probe was attached to specific amplicons for detection, and each amplicon from multiplex PCR was selectively detected within approximately 15 min. Notably, this method requires no electric power and contributes to the realization of on-site NAT detection. This study presents a simple and rapid method for the selective detection of multiplex PCR amplicons using DNA–DNA hybridization.

Our study successfully fabricated sourness and saltiness sensors and investigated the response toward acetic acid and sodium chloride as the sourness and saltiness sample solutions, respectively. The sensors were made using a lipid membrane with a mixture of two materials. The fabricated sensors can detect the concentration of a small amount of 0.03 mM for the sourness sensor and 0.316 mM for the saltiness sensor, much lower than the human tongue threshold. Moreover, the sensors show a directly proportional response for both sourness and saltiness sensors in the range of 0.03–3 mM of acetic acid and 0.316–31.6 mM of sodium chloride, respectively. The interaction between positive charge in the lipid membrane and anionic species in the sample solution was believed to be the sensing mechanism in this research. Both sensors were refabricated three times, and the saltiness sensor exhibited a similar response when exposed to 3.16 mM of sodium chloride, while the sourness sensor still has to improve its reproducibility. In addition, the fabricated sensors were also tested on three consecutive days to observe the stability.

The polymer purpald (4-amino-3-hydrazino-5-mercapto-1,2,4-triazole) film on glassy carbon electrode (p-Purpald@GCE) was fabricated using purpald monomer by electropolymerization method, and the modified electrode was applied as a probe for the simultaneous sensing of ascorbic acid (AA), uric acid (UA), L-cysteine (L-Cys) and lipoic acid (LA). The modified p-Purpald@GCE was well characterized by Scanning electrode microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Cyclic Voltammetry (CV), Electrochemical impedance spectroscopy (EIS) and Differential Pulse Voltammetry (DPV) techniques. CV, EIS results were confirmed the good electrocatayst nature of p-Purpald@GCE. Independent and simultaneous detection of AA, UA, L-Cys, and LA ware performed by DPV method. For Independent detection, based on the oxidation current changes, we have calculated the limit of detection (LOD) of 392, 137, 341 and 200 nM (LOD) = 3S/m) for AA, UA, L-Cys and LA, respectively. The simultaneous detection of AA, UA, L-Cys, and LA executed and LOD found to be 364, 132, 275 and 192 nM, respectively. The modified electrode shows the high selectivity towards AA, UA, L-Cys and LA even in the presence of high concentration of other interferences. The developed sensor technique will be useful for the sensitive and simultaneous detection of AA, UA, L-Cys, and LA in food and clinical samples.

Carbon dots (CDs) are the most promising nanomaterials of zero-dimensional nanoparticle materials because they have strong fluorescence properties, good photoluminescence conversion, stability, and inter-charge transfer performance. CDs also have the advantages of good biocompatibility, low toxicity, and hydrophilic properties. CDs are generally synthesized through two approaches: top-down and bottom-up. Green synthesis of environmentally friendly CDs with easy and simple procedures has become an exciting concern lately and in the future. In addition to green synthesis, green carbon sources such as biomass waste have promising potential. The advantages of fluorescence CDs make them applicable in food sensing. Fluorescent resonance energy transfer, photoinduced electron transfer, and internal screening effect mechanisms enable precise detection of heavy metal ions, food additives, foodborne pathogens, nutrient composition, pesticide residues, and veterinary drug residues. This review provides a brief overview and future perspectives on green synthesis CDs and their applications for more advanced food sensing in food safety analysis.

Infections cause concern for mankind, and sometimes their diagnosis may take much time. Owing to its high sensitivity, rapidity, and specificity, the immunochromatographic assay (ICA) is used widely to diagnose infections. The use of the ICA for this purpose makes it possible to detect dangerous diseases early, prevent their progress, strongly reduce the treatment cost and mortality, and increase life expectancy. One promising ICA format involves the use of gold nanoparticles. Here we present the principles and history of ICA use for the diagnosis of infections and discuss the prospects for using gold nanoparticles in the ICA. We present data on the methods used to make and conjugate gold nanoparticles and on the effect of particle size and shape on ICA sensitivity. We discuss the prospects for using the ICA to diagnose bacterial and viral infections, and we review instrumental methods for quantifying ICA results. Finally, we discuss the prospects for using the gold nanoparticle–based ICA in the diagnosis of infections.

This study focuses on the first-ever high-sensitivity, low-cost, and quick response electrochemical estimation of metadoxine (MTD) in pharmaceuticals and human blood serum using a non-enzymatic nanocomposite modified glassy carbon electrode (CuO/CH/GCE) loaded with chitosan. The electroactive surface of GCE was produced by drop-casting a suspension of CuO/CH nanocomposite in N,N-dimethylformamide (DMF) onto the non-enzymatic electrode surface. Synthesized nanocomposite was characterised by using XRD, XPS, EDX, TEM, Raman and FESEM techniques. EIS technique was utilized to study the enhanced charge-transfer phenomenon occurring at the surface of modified sensor. The electrooxidation of MTD at CuO/CH/GCE surface is depending at pH of supporting electrolyte, scan rate and concentration of analyte. CV and SWV technique were used to carry out electrochemical study, optimised voltammetric response is observed in the BR buffer at pH 2.5, with irreversible diffusion-controlled process. Within the linear concentration range of MTD from 1.99 μg/L to 29.56 μg/L, this sensor exhibited lowest LOD (0.64 μg/L) and LOQ (2.14 μg/L). The MTD in pharmaceutical formulation and human blood serum can be determined with this highly selective peak potential (Ep ∼ 1.2 V), repeatable (%RSD 0.91), and reproducible (%RSD 2.31) method. The average percentage recovery in human blood serum and pharmaceutical formulation is 99.89% and 99.90%. This paper reports a lowest LOD value for MTD detection in the comparison with other reported methods (Table S1). None of the selected excipients were found to interfere more than 5% with redox potential of MTD without affecting the performance of sensor.

In this work, nickel oxide (NiO) nanostructures deposited by glancing angle deposition (GLAD) are fabricated to achieve highly specific catalytic electrooxidation of lactate, replacing the natural enzyme lactate oxidase for electrochemical detection of lactate in sweat. GLAD NiO electrodes exhibit high sensitivity (412 μA mM⁻¹ cm⁻²), wide linear detection range (1–45 mM), low detection limit (3 μM), and excellent specificity in artificial sweat samples. The unique microporous structure of the GLAD NiO electrodes, combined with their high surface area, high catalytic activity, and excellent conductivity, enhance the performance of the sensor and demonstrate their exceptional effectiveness in the sensitive detection of lactate. In-house fabricated gold counter, and stable solid-state Ag/AgCl reference electrodes, all fabricated on a flexible PET substrate along with the GLAD NiO working electrode, demonstrate performance comparable to commercial Pt auxiliary and Ag/AgCl (1M KCl) reference electrodes in lactate detection, along with outstanding flexibility, tested at various radii of curvature (15 mm, 7.5 mm, and 5 mm). The durable and long-lasting GLAD NiO electrode chips overcome numerous challenges in transport, storage, and operation, paving the way for the development of wearable lactate sensors that can detect lactate levels in sweat.

Synthetic single-stranded oligonucleotides play crucial roles in DNA amplification reactions for various applications, such as serving as primers, enabling magnetic separation, and generating dsDNA for subsequent digestion. Typically, these oligos are added in excess to ensure rapid binding to their intended targets. However, while performing rolling circle amplification (RCA) using phi29 DNA polymerase, we observed a decrease in amplification efficiency when oligos were present in the reaction. This phenomenon was consistently observed in two separate laboratories, prompting this study to delve into the root causes responsible for the decline in RCA efficiency. The lowered efficiency was consistent regardless of the manufacturer or any mutations in the phi29 polymerase. We identified several variables that influenced RCA efficiency, mainly the length of the oligos used and the presence of modifications, particularly those obstructing 3’ end digestion. This strongly suggests that the exonuclease domain of phi29 DNA polymerase is responsible for the competition-based inhibition. Our investigation shows that even picomole quantities of oligos can significantly reduce total DNA production during the phi29 DNA polymerase-mediated amplification process. Conversely, the addition of oligos to the reaction did not impede the efficiency of Bst 3.0 polymerase, likely due to the lack of an exonuclease domain of said polymerase. While increasing the quantity of phi29 DNA polymerase in the reaction partially alleviated the adverse effects of excess oligos, we believe it is crucial to carefully optimize the oligo quantities to achieve maximum amplification of the desired targets.