Patsamon Rijiravanich

The growing demand for decentralised and point-of-care (POC) nucleic acid testing has increased interest in label-free, sequence-specific DNA biosensors and computational approaches that can guide their design before extensive experimental optimisation. Here, an in silico workflow was first employed to evaluate a gold nanoparticle (AuNP)-amplified, target-induced DNA displacement assay. Nearest-neighbour duplex thermodynamics, DNA secondary-structure analysis, and High Ambiguity Driven biomolecular DOCKing (HADDOCK) were used to assess sequence complementarity and displacement behaviour. The analyses confirmed Watson–Crick complementarity among the electrode capture, reporter, and target sequences and identified an unintended mismatch in the magnetic bead-capture probe. HADDOCK analyses using default RNA and explicit DNA settings consistently favoured target over non-target displacement, although control poses were more setting-sensitive. Experimental testing subsequently provided supporting evidence for the computational assessment. Electrochemical measurements showed the anticipated signal hierarchy of target > non-target > buffer, although differences were not statistically significant at the replicate numbers tested. The magnetic bead platform produced weak, non-differential responses, consistent with the sequence-level design limitation identified computationally. Together, these findings demonstrate the utility of computational pre-screening for interrogating displacement mechanisms, identifying correctable design errors, and guiding rational experimental optimisation of nucleic acid biosensors. No statistically significant target discrimination was achieved at the replicate numbers tested, and the proposed corrected bead-capture sequence has not been experimentally validated.

A novel screen-printing approach was employed to fabricate molybdenum disulfide (MoS ₂ ) based membranes using exfoliation-free solvothermally synthesized ink-like MoS ₂ gel and Whatman filter paper (WFP).

Ensuring food safety is paramount for the food industry and global health concerns. In this study, we have developed a method for the detection of prevalent foodborne pathogenic bacteria, including Escherichia coli, Salmonella spp., Listeria spp., Shigella spp., Campylobacter spp., Clostridium spp., and Vibrio spp., utilizing antibody-aptamer arrays. To enhance the fluorescence signals on the microarray, the mesoporous silica nanoparticles (MSNs) conjugated with fluorescein, streptavidin, and seven detection antibodies-biotin were employed, forming fluorescein doped mesoporous silica nanoparticles conjugated with detection antibodies (MSNs-Flu-SA-Abs) complexes. The array pattern was designed for easy readability and enabled the simultaneous detection of all seven foodborne pathogens, referred to as the 7FP-biochip. Following the optimization of MSNs-Flu-SA-Abs complexes attachment and enhancement of the detection signal in fluorescent immunoassays, a high level of sensitivity was achieved. The detection limits for the seven pathogens in both buffer and food samples were 10² CFU/mL through visual screening, with fluorescent intensity quantification achieving levels as low as 20-34 CFU/g were achieved on the antibody-aptamer arrays. Our antibody-aptamer array offers several advantages, including significantly reduced nonspecific binding with no cross-reaction between bacteria. Importantly, our platform detection exhibited no cross-reactivity among the tested bacteria in this study. The multiplex detection of foodborne pathogens in canned tuna samples with spiked bacteria was successfully demonstrated in real food measurements. In conclusion, our study presents a promising method for detecting multiple foodborne pathogens simultaneously. With its high sensitivity and specificity, the developed antibody-aptamer array holds great potential for enhancing food safety and public health.

Dengue virus (DENV) infection, which is transmitted by Aedes mosquitoes, is a major public health concern in tropical and subtropical countries. With an annual incidence of approximately 10 million cases and 20,000-25,000 deaths, particularly among children, there is an urgent need for practical diagnostic tools. The presence of dengue non-structural protein 1 (NS1) during early infection has been linked to cytokine release, vascular leakage, and endothelial dysfunction, making it a potential marker for severe dengue. Paper-based immunoassays such as lateral flow assays (LFAs) and microfluidic paper-based analytical devices (PADs) have gained popularity as diagnostic tests due to their simplicity, rapidity, inexpensiveness, specificity, and ease of interpretation. However, conventional paper-based immunoassays for dengue NS1 detection typically rely on visual inspection, yielding only qualitative results. To address this limitation and enhance sensitivity, we proposed a highly portable NS1 dengue detection assay on a Paper-based Analytical Device (PAD), namely, DEN-NS1-PAD, that integrates a smartphone application as a colorimetric and quantitative reader. The development system enables direct quantification of NS1 concentrations in clinical samples. Serum and blood samples obtained from patients were utilized to demonstrate the system prototype performance. The results were obtained immediately and can be employed for clinical assessment, both in well-equipped healthcare facilities and resource-limited settings. This innovative combination of a paper-based immunoassay with a smartphone application offers a promising approach for enhanced detection and quantification of dengue NS1 antigen. By augmenting sensitivity beyond the capabilities of the naked eye, this system holds great potential for improving clinical decision-making in dengue management, particularly in remote or underserved areas.

Lead (Pb²⁺) contamination in blood can trigger the developmental of disabilities in children and some serious problems of chronic illnesses. In this work, a simple label-free GR5 DNAzyme and gold nanoparticles were applied in a colorimetric assay for Pb²⁺ detection. Using this method, the reaction and cleaving process between DNAzyme and lead were perfect. The experiment was successfully tested for the detection of Pb²⁺ in the buffer. The visual detection limit of this colorimetric assay obtained was 10 nM. The biosensor showed excellent specificity for Pb²⁺ compared to other metal ions.