Sensitivity of photoelctrocehmical aptasensor using spiral nanorods for detecting antiobiotic levels in experimental and real samples

Sulfur defect-engineered Bi2S3-x/In2S3-y mediated signal enhancement of photoelectrochemical sensor for lead ions detection

Lead ions (Pb2+) are heavy metal ions that are harmful to living organisms and ecosystems. It is important to realize sensitive detection of Pb2+ in the environment. In this study, a signal enhancement photoelectrochemical (PEC) sensor with high sensitivity was constructed for the detection of Pb2+. Firstly, to obtain excellent electron transfer performance, sulfur defect-engineered Bi2S3-x/In2S3-y mediated signal enhancement formed by Bi2S3 and In2S3 with well-matched structure in terms of energy level as the substrate materials. In this case, the introduction of sulfur vacancies further affects the electronic structure of the material, which significantly improves the electrical conductivity and effectively increases the electron transfer rate. In addition, the as-synthesized Cu@Cu2O nanosphere is chosen as the marker to accelerate the electron transfer through the surface plasmon resonance effect of Cu. The constructed sensor was able to detect Pb2+ in the range of 1 ng mL-1-100 μg mL-1 with a limit of detection of 19.2 pg mL-1. The sensor exhibits good reproducibility, specificity, and stability, indicating such PEC sensor can achieve the sensitive detection of Pb2+ in the environment. This work paves a new way for the construction of PEC sensors and the specific PEC detection of Pb2+ in environmental waters.

Nanomaterial surface modification toolkit: Principles, components, recipes, and applications

Surface-functionalized nanostructures are at the forefront of biotechnology, providing new opportunities for biosensors, drug delivery, therapy, and bioimaging applications. The modification of nanostructures significantly impacts the performance and success of various applications by enabling selective and precise targeting. This review elucidates widely practiced surface modification strategies, including click chemistry, cross-coupling, silanization, aldehyde linkers, active ester chemistry, maleimide chemistry, epoxy linkers, and other protein and DNA-based methodologies. We also delve into the application-focused landscape of the nano-bio interface, emphasizing four key domains: therapeutics, biosensing, environmental monitoring, and point-of-care technologies, by highlighting prominent studies. The insights presented herein pave the way for further innovations at the intersection of nanotechnology and biotechnology, providing a useful handbook for beginners and professionals. The review draws on various sources, including the latest research articles (2018-2023), to provide a comprehensive overview of the field.

High efficient electrochemical biosensor based on exonuclease-Ⅲ-assisted dual-recycling amplification for ultrasensitive detection of kanamycin

A target-triggered and exonuclease-Ⅲ-assisted strand displacement, dual-recycling amplification reaction-based biosensor was developed for the rapid, ultrasensitive and accurate detection of kanamycin. The robust profiling platform was constructed using high conductive MXene/VS₂ for the electrode surface modification and high active CeCu₂O₄ bimetallic nanoparticles as nanozyme to improve the sensitivity as well as the catalytic signal amplification of the biosensor. Using the dual supplementary recycling of primer DNA and hairpin DNA, the electrochemical platform could accurately detect kanamycin to as low as 0.6 pM from the range of 5 pM to 5 μM. By profiling five other antibiotics, this platform exhibited high specificity, enhanced repeatability and reproducibility. Based on these intrinsic characteristics and by utilizing milk and water samples, the as-designed biosensor offers a remarkable strategy for antibiotic detection due to its favorable analytical accuracy and reliability, thereby demonstrating potential application prospect for various antibiotic biosensing in food quality control, water contamination detection and biological safety analysis.

Screening of a Sialyllactose-Specific Aptamer and Engineering a Pair of Recognition Elements with Unique Fluorescent Characteristics for Sensitive Detection of Sialyllactose

A single-stranded DNA (ssDNA) aptamer specific for 6'-sialyllactose (6'-SL) was screened through magnetic separation-based SELEX and post-SELEX truncation and used to construct unique aptamer bio-dots for sensitive detection of 6'-SL. Eighteen rounds of screening were conducted during the SELEX process. The ssDNA aptamer Apt9 (K_d = 152.3 nM) with a length of 79 nucleotides (nt) was demonstrated as the optimal aptamer candidate after affinity and specificity evaluation. Then, Apt9 was truncated and optimized according to secondary structure and molecular docking. A 35 nt truncated aptamer Apt9-1 (K_d = 91.75 nM) with higher affinity than Apt9 was finally obtained. Furthermore, Apt9-1 was used to synthesize bio-dots as a new recognition element of 6'-SL, and the aminobenzene boric acid functionalized carbon dots were employed as the other recognition element. With the respective fluorescent characteristics, the two quantum dots (QDs) were made a pair to construct a 6'-SL fluorescent biosensor. The linear detection range of the biosensor is 10 μM to 5 mM, and the detection limit is 0.9 μM. With the advantages of time-saving, high efficiency, and simplicity in the actual sample detection, the screened aptamer and dual-QD-based biosensor have broad application prospects in 6'-SL detection.

Triple-Helix Molecular Switch Triggered Cleavage Effect of DNAzyme for Ultrasensitive Electrochemical Detection of Chloramphenicol

The abuse of chloramphenicol (CAP) in animal-derived products leads to serious food safety problems, so the sensitive and accurate determination of CAP residues has great noteworthiness for public health. Herein, we present a novel electrochemical aptasensor that incorporates a poly(diallyldimethylammonium chloride) functionalized graphene/Ag@Au nanosheets (PDDA-Gr/Ag@Au NSs) composite modified electrode and a DNAzyme signal amplification effect triggered by a triple-helix molecular switch (THMS) for detecting CAP. The PDDA-Gr/Ag@Au NSs composite has the advantages of high surface area, great conductivity, and dispersibility and has successfully improved the electrochemical performance of the electrode. Specific interaction with CAP will cause the signal transduction probe (STP) to be released from the THMS. After that, the DNAzyme will be activated with the help of Pb²⁺ and remove the immobilized signal probe on the electrode surface. The signal change was recorded by square wave voltammetry (SWV) and led to an accurate quantification of CAP. With all these features, the proposed sensing strategy yielded a satisfactory analytical performance with linearity between 1 pM and 1 μM and a limit of detection of 18.6 fM. Furthermore, the aptasensor shows excellent specificity for CAP in the presence of other antibiotics and resists interference with other common metal ions. Importantly, the performance is not diminished when the constructed aptasensor is applied to measuring CAP in milk powder. This THMS-based method is easy to design, and alteration to different targets can be achieved by simply replacing the aptamer sequence in the THMS. Therefore, this method shows significant prospects as a flexible platform for accurate monitoring of antibiotic residues in foodstuffs.

Electrochemical Aptasensors for Antibiotics Detection: Recent Achievements and Applications for Monitoring Food Safety

Antibiotics are often used in human and veterinary medicine for the treatment of bacterial diseases. However, extensive use of antibiotics in agriculture can result in the contamination of common food staples such as milk. Consumption of contaminated products can cause serious illness and a rise in antibiotic resistance. Conventional methods of antibiotics detection such are microbiological assays chromatographic and mass spectroscopy methods are sensitive; however, they require qualified personnel, expensive instruments, and sample pretreatment. Biosensor technology can overcome these drawbacks. This review is focused on the recent achievements in the electrochemical biosensors based on nucleic acid aptamers for antibiotic detection. A brief explanation of conventional methods of antibiotic detection is also provided. The methods of the aptamer selection are explained, together with the approach used for the improvement of aptamer affinity by post-SELEX modification and computer modeling. The substantial focus of this review is on the explanation of the principles of the electrochemical detection of antibiotics by aptasensors and on recent achievements in the development of electrochemical aptasensors. The current trends and problems in practical applications of aptasensors are also discussed.

An Effective Label-Free Electrochemical Aptasensor Based on Gold Nanoparticles for Gluten Detection

Nanomaterials can be used to modify electrodes and improve the conductivity and the performance of electrochemical sensors. Among various nanomaterials, gold-based nanostructures have been used as an anchoring platform for the functionalization of biosensor surfaces. One of the main advantages of using gold for the modification of electrodes is its great affinity for thiol-containing molecules, such as proteins, forming a strong Au-S bond. In this work, we present an impedimetric biosensor based on gold nanoparticles and a truncated aptamer for the quantification of gluten in hydrolyzed matrices such as beer and soy sauce. A good relationship between the R_ct values and PWG-Gliadin concentration was found in the range between 0.1–1 mg L⁻¹ of gliadin (corresponding to 0.2–2 mg L⁻¹ of gluten) with a limit of detection of 0.05 mg L⁻¹ of gliadin (corresponding to 0.1 mg L⁻¹ of gluten). The label-free assay was also successfully applied for the determination of real food samples.