Search Results (69)

The development of gas sensors with high sensitivity and low operating temperatures is essential for practical applications in environmental monitoring and industrial safety. SnO₂-based gas sensors, despite their widespread use, often suffer from high working temperatures and limited sensitivity to H₂ gas, which presents significant challenges for their performance and application. This study addresses these issues by introducing a novel SnO₂-based sensor featuring a three-dimensional (3D) nanostructure, designed to enhance sensitivity and allow for room-temperature operation. This work lies in the use of a 3D anodic aluminum oxide (AAO) template to deposit SnO₂ nanoparticles through ultrasonic spray pyrolysis, followed by modification with platinum (Pt) nanoparticles to further enhance the sensor’s response. The as-prepared sensors were extensively characterized, and their H₂ sensing performance was evaluated. The results show that the 3D nanostructure provides a uniform and dense distribution of SnO₂ nanoparticles, which significantly improves the sensor’s sensitivity and repeatability, especially in H₂ detection at room temperature. This work demonstrates the potential of utilizing 3D nanostructures to overcome the traditional limitations of SnO₂-based sensors. Full article

Leptin is an adipocyte-derived hormone that orchestrates different physiological processes, including energy balance, thermogenesis, immune regulation, reproduction, and tissue remodeling. These effects are mediated through interaction with the CRH2 domain of the leptin receptor (Ob-R). While the structural aspects of the interaction between leptin and Ob-R have been first studied in humans and mice, comparative analyses of stability across mammalian species under physiologically relevant microenvironmental conditions remain limited. We performed a bioinformatics-driven structural, stability, and thermodynamic characterization of the leptin–CRH2 complex. This included structural homology modeling using a full-length template, interface mapping, and binding energy estimation. Additionally, we analyzed the effect of pH, ionic strength, and temperature on complex formation to mimic physiological and pathological tissue conditions to enhance clarity in the structural features and stability of the complex. Our results show that the interaction is primarily enthalpy-driven and is sensitive to temperature, ionic strength, and pH changes for all heterodimers analyzed here. The predicted binding free energy (ΔG) ranged from −10.50 to −16.81 kcal/mol across species. The integrated bioinformatic analyses suggest that subtle sequence variations influence the stability and environmental responsiveness of the complex. This study provides a molecular framework for understanding how leptin–Ob-R binding adapts across species and tissue contexts. Full article

Molybdenum disulfide (MoS₂) has gained attention for its promising gas-sensing capabilities due to its high surface area and tunable electronic properties. In this study, we investigate the time-dependent growth (under constant conditions) of sputtered MoS₂ films on ZnO nanorods and their impact on NO₂ sensing performance. ZnO nanorods, synthesized via a hydrothermal method, provide a high-surface-area template to enhance charge transport and gas adsorption. Gas-sensing experiments revealed a strong correlation between MoS₂ thickness and NO₂ response, with the 25-min-sputtered MoS₂ film exhibiting the highest response of 20.9%. The synergistic interaction between MoS₂ and ZnO nanorods facilitated charge transfer and enhanced adsorption sites for NO₂ molecules. These findings emphasize the critical role of time-dependent growth of MoS₂ film in modulating gas-sensing performance and provide insights into designing high-sensitivity NO₂ sensors at room temperature. This study contributes to the development of hybrid MoS₂/ZnO nanostructures for next-generation environmental monitoring applications. Full article

Due to its widespread distribution in industrial, commercial, and residential settings, xylene detection is crucial. In this study, carbon sphere templates and NaHCO₃ etching were used to synergistically prepare WO₃ with uniform macropores, which was then decorated with Au elements. The findings demonstrated that the Au-decorated WO₃-etched sample (WO₃-1%E+Au) had the best sensing performance for 100 ppm xylene (response value: 21.3, optimal operating temperature: 360 °C) and short response/recovery time (1 s/11 s). The etching of NaHCO₃ and the synergistic carbon sphere templates were responsible for the sensing performance, as they enhanced the sample surface’s specific surface area and roughness while also supplying additional active sites. Furthermore, the sensor’s sensitivity and selectivity to xylene were enhanced by the coupling effect and dehydrogenation catalysis of the noble metal Au. The results of this work advance our knowledge of gas-sensing mechanisms and offer guidance for the creation of extremely sensitive and selective xylene gas sensors. Full article

Inverse opal (IO) structures based on photonic colloidal crystal (PCC) templates are types of materials that possess unique optical properties due to their ordered arrays. These materials have the ability to manipulate the propagation of light, producing unique reflection spectra and structural colours. Due to these properties, IOs have been used as optical sensors for various applications such as the detection of physical, chemical, and biological entities. This review begins with a brief introduction of PCCs, IOs and their preparation procedures. The recent advancements in the applications of IOs for sensing temperature, pH, humidity, chemical compounds (such as organic solvents and heavy metal ions), and biological entities (such as tumour cells, viruses and bacteria) are then discussed in detail. The review also explores strategies and techniques aimed at enhancing the sensitivity and lowering the limit of detection of IO-based sensors. Finally, it addresses the current challenges, existing limitations, and prospective future directions in the development and deployment of IO-based sensors. Full article

DNA phosphorothioate (PT) modifications, characterized by the replacement of a non-bridging phosphate oxygen atom with a sulfur atom, are widely observed in bacterial genomes. Sensitive detection of phosphorothioate is crucial for elucidating their biological roles and functions. Herein, we developed an innovative method that leverages oligonucleotide-templated reactions (OTRs) and fluorogenic oligonucleotide probes. By optimizing temperature, probe sequence length, and the relative distance between PT position and the fluorophore probe, we achieved sensitive detection for DNA PT modifications through fluorogenic signal amplification, which provides an efficient and cost-effective approach for sensitive detection of phosphorothioate-modified DNA. Full article

Rolling circle amplification (RCA) at ambient temperature is prone to false positive signals during nucleic acid detection, which makes it challenging to establish an efficient RCA detection method. The false positive signals are primarily caused by binding of non-target nucleic acids to the circular single-stranded template, leading to non-specific amplification. Here, we present an RCA method for miRNA detection at 37 °C using two circular ssDNAs, each of which is formed by ligating the intramolecularly formed nick (without any splint) in a secondary structure. The specific target recognition is realized by utilizing low concentrations (0.1 nM) of circular ssDNA1 (C1). A phosphorothioate modification is present at G*AATTC on C1 to generate a nick for primer extension during the primer self-generated rolling circle amplification (PG-RCA). The fragmented amplification products are used as primers for the following RCA that serves as signal amplification using circular ssDNA2 (C2). Notably, the absence of splints and the low concentration of C1 significantly inhibits non-target binding, thus minimizing false positive signals. A high concentration (10 nM) of C2 is used to carry out linear rolling circle amplification (LRCA), which is highly specific. This strategy demonstrates a good linear response to 0.01–100 pM of miRNA with a detection limit of 7.76 fM (miR-155). Moreover, it can distinguish single-nucleotide mismatch in the target miRNA, enabling the rapid one-pot detection of miRNA at 37 °C. Accordingly, this method performs with high specificity and sensitivity. This approach is suitable for clinical serum sample analysis and offers a strategy for developing specific biosensors and diagnostic tools. Full article

Background: Epigenetic biomarkers, particularly CpG methylation, are increasingly employed in clinical and forensic settings. However, we still lack a cost-effective, sensitive, medium-scale method for the analysis of hundreds to thousands of user-defined CpGs suitable for minute DNA input amounts (<10 ng). In this study, motivated by promising results in the genetics field, we investigated single-molecule molecular inversion probes (smMIPs) for simultaneous analysis of hundreds of CpGs by using an example set of 514 age-associated CpGs (Zhang model). Methods: First, we developed a novel smMIP design tool to suit bisulfite-converted DNA (Locksmith). Then, to optimize the capture process, we performed single-probe capture for ten selected, representative smMIPs. Based on this pilot, the full smMIP panel was tested under varying capture conditions, including hybridization and elongation temperature, smMIP and template DNA amounts, dNTP concentration and elongation time. Results: Overall, we found that the capture efficiency was highly probe-(and hence, sequence-) dependent, with a heterogeneous coverage distribution across CpGs higher than the 1000-fold range. Considering CpGs with at least 20X coverage, we yielded robust methylation detection with levels comparable to those obtained from the gold standard EPIC microarray analysis (Pearsons’s r: 0.96). Conclusions: The observed low specificity and uniformity indicate that smMIPs in their current form are not compatible with the lowered complexity of bisulfite-converted DNA. Full article

Tomato leaf curl New Delhi virus (ToLCNDV) and tomato yellow leaf curl virus (TYLCV) are two important viral pathogens that severely affect Solanaceae and Cucurbitaceae plants. In order to reduce the further spread of these viruses, it is crucial to establish an efficient and reliable method to accurately detect the viruses. In this study, a multiplex PCR assay for the simultaneous detection of TYLCV and ToLCNDV was established. Three primer pairs designed from conserved regions within the coat protein or movement protein-encoding regions of the respective viruses were employed in the assay. The optimization of parameters such as primer concentration was set at 0.15 μM/0.15 μM, 0.25 μM/0.25 μM, and 0.50 μM/0.50 μM for ToLCNDV-DNA-A-F/R, TYLCV-F/R, and ToLCNDV-DNA-B-F/R primer pairs. At optimal primer concentrations, the multiplex PCR method demonstrates effective performance with an annealing temperature ranging from 51 °C to 66 °C. The specificity of the assay evaluated by testing against other begomoviruses showed no evidence of cross-amplification. Further sensitivity analysis performed using a serially diluted plasmid containing viral targets as templates demonstrated high sensitivity with a detection limit of 10³ copies/μL. Field surveys utilizing the multiplex PCR assay successfully identified the infection of TYLCV and ToLCNDV in field-collected samples. Full article

In this study, a simple and easy synthesis strategy to realize the modification of AuHgPt nanoalloy materials on the surface of ITO glass at room temperature is presented. Gold nanoparticles as templates were obtained by electrochemical deposition, mercury was introduced as an intermediate to form an amalgam, and then a galvanic replacement reaction was utilized to successfully prepare gold–mercury–platinum (AuHgPt) nanoalloys. The obtained alloys were characterized by scanning electron microscopy, UV–Vis spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction techniques. The electrochemical sensing performance of the AuHgPt-modified electrode for hydrogen peroxide was evaluated by cyclic voltammetry and chronoamperometry. Under light conditions, the AuHgPt-modified electrode exhibited a desirable current response in the detection of hydrogen peroxide due to the synergistic effect of the localized surface plasmon resonance effect inherent in gold nanoparticles, and this synergistic effect improved the sensitivity of hydrogen peroxide detection. Meanwhile, the AuHgPt-modified electrode also exhibited better stability and reproducibility, which makes the modified electrode have great potential for various applications in the field of electrochemical sensing. Full article

The Phi29 DNA polymerase is renowned for its processivity in synthesizing single-stranded DNA amplicons by rolling around a circularized DNA template. However, DNA synthesis rolling circle amplification (RCA) is significantly hindered by the secondary structure in the circular template. To overcome this limitation, an engineered circular template without secondary structure could be utilized to improve the sensitivity of RCA-based assays without increasing its complexity. We herein proposed an entropy-driven special RCA technology for the detection of HPV16 E7 gene at room temperature. The strategy is composed of a molecular beacon containing a loop region for nucleic acid target recognition and a stem region to initiate RCA. With the target analyte, the stem region of the molecular beacon will be exposed and then hybridized with a special circular template to initiate the DNA amplification. We tested different designs of the molecular beacon sequence and optimized the assay’s working conditions. The assay achieved a sensitivity of 1 pM in 40 min at room temperature. The sensitivity of this assay, at 1 pm, is about a hundred-fold greater than that of conventional linear RCA performed in solution. Our proposed sensor can be easily reprogrammed for detecting various nucleic acid markers by altering the molecular beacon’s loop. Its simplicity, rapid assay time, and low cost make it superior to RCA sensors that utilize similar strategies. Full article

Background: Bovine respiratory syncytial virus (BRSV) is a significant cause of bovine respiratory disease, resulting in significant losses to the cattle industry. For rapid detection of BRSV, a real-time recombinase-aided isothermal amplification assay (qRT-RAA) based on the F gene of BRSV was developed in this study. Results: The developed qRT-RAA assay showed good exponential amplification of the target fragment in 20 min at a constant temperature of 39 °C. And this assay displayed a high specificity for BRSV, without cross-reactions with Infectious Bovine Rhinotracheitis Virus (IBRV), Bovine Parainfluenza Virus Type 3 (BPIV3), Bovine Viral Diarrhea Virus (BVDV), and Bovine Coronavirus (BCoV). With the standard RNA of BRSV serving as a template, the limit of detection for qRT-RAA was 102 copies/μL. We examined ninety-seven clinical samples from cattle with respiratory disease using this method and determined a positive rate of 7.2% (7/97), consistent with results using the classical PCR method reported previously. Conclusions: A qRT-RAA assay for BRSV detection was established in this study. The method is specific and sensitive and can be completed within 20 min at 39 °C. These works demonstrate that the generated qRT-RAA assay is an effective diagnostic tool for rapidly detecting BRSV in resource-limited settings, which may be applied for the clinical detection of BRSV. Full article

Ethyl acetate is a critical medical indicator for detecting certain types of cancer. However, at present, available sensitive materials often exhibit drawbacks, such as high operating temperatures and poor responses to low concentrations of ethyl acetate. In this study, a ZnO nanorod sensing material was prepared using high-temperature annealing and a hydrothermally synthesized metal-organic framework (MOF) as a template. Au nanodots (AuNDs) were subsequently modified on the ZnO nanorods using an in situ ion reduction, which provided a better dispersion of Au nanodots compared with that obtained using the common reductant method. A variety of characterization methods indicate that the highly dispersed AuNDs, which possess a high catalytic activity, were loaded onto the surface as active centers, leading to a significant augmentation in the adsorption of oxygen on the surface compared with the original ZnO material. Consequently, the AuND@ZnO material exhibited heightened responsiveness to ethyl acetate at a lower operating temperature. The Au@ZnO-based sensor has a response rate (R_a/R_g) of 41.8 to 20 ppm ethyl acetate gas at 140 °C, marking a 17.4-fold increase compared with that of the original material. Due to its low power consumption and high responsiveness, AuND@ZnO is a promising candidate for the detection of ethyl acetate gas in medical applications. Full article

Multifunctional targeted drug delivery systems have been explored as a novel cancer treatment strategy to overcome limitations of traditional chemotherapy. The combination of photodynamic therapy and chemotherapy has been shown to enhance efficacy, but the phototoxicity of traditional photosensitizers is a challenge. In this study, we prepared a multi-sensitive composite hydrogel containing gold nanoclusters (Au NCs) and the temperature-sensitive antitumor drug 5-fluorourac il (5-FU) using carboxymethyl cellulose (Carr) as a dual-functional template. Au NCs were synthesized using sodium borohydride as a reducing agent and potassium as a promoter. The resulting Au NCs were embedded in the Carr hydrogel, which was then conjugated with lactobionic acid (LA) as a targeting ligand. The resulting Au NCs/5-FU@Carr-LA composite hydrogel was used for synergistic photodynamic therapy (PDT), photothermal therapy (PTT), and chemotherapy. Au NCs/5-FU@Carr-LA releases the drug faster at pH 5.0 due to the acid sensitivity of the Carr polymer chain. In addition, at 50 °C, the release rate of Au NCs/5-FU@Carr-LA is 78.2%, indicating that the higher temperature generated by the photothermal effect is conducive to the degradation of Carr polymer chains. The Carr hydrogel stabilized the Au NCs and acted as a matrix for drug loading, and the LA ligand facilitated targeted delivery to tumor cells. The composite hydrogel exhibited excellent biocompatibility and synergistic antitumor efficacy, as demonstrated by in vitro and in vivo experiments. In addition, the hydrogel had thermal imaging capabilities, making it a promising multifunctional platform for targeted cancer therapy. Full article

Pyocyanin is considered a maker of Pseudomonas aeruginosa (P. aeruginosa) infection. Pyocyanin is among the toxins released by the P. aeruginosa bacteria. Therefore, the development of a direct detection of PYO is crucial due to its importance. Among the different optical techniques, the Raman technique showed unique advantages because of its fingerprint data, no sample preparation, and high sensitivity besides its ease of use. Noble metal nanostructures were used to improve the Raman response based on the surface-enhanced Raman scattering (SERS) technique. Anodic metal oxide attracts much interest due to its unique morphology and applications. The porous metal structure provides a large surface area that could be used as a hard template for periodic nanostructure array fabrication. Porous shapes and sizes could be controlled by controlling the anodization parameters, including the anodization voltage, current, temperature, and time, besides the metal purity and the electrolyte type/concentration. The anodization of aluminum foil results in anodic aluminum oxide (AAO) formation with different roughness. Here, we will use the roughness as hotspot centers to enhance the Raman signals. Firstly, a thin film of gold was deposited to develop gold/alumina (Au/AAO) platforms and then applied as SERS-active surfaces. The morphology and roughness of the developed substrates were investigated using scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. The Au/AAO substrates were used for monitoring pyocyanin secreted from Pseudomonas aeruginosa microorganisms based on the SERS technique. The results showed that the roughness degree affects the enhancement efficiency of this sensor. The high enhancement was obtained in the case of depositing a 30 nm layer of gold onto the second anodized substrates. The developed sensor showed high sensitivity toward pyocyanin with a limit of detection of 96 nM with a linear response over a dynamic range from 1 µM to 9 µM. Full article