Nur Fatihah Mohd Zaidi

Latent tuberculosis infection (LTBI) remains a major global health challenge due to the lack of rapid, sensitive, and biomarker-based diagnostic tools. This study addresses the need to develop a label-free electrochemical aptasensor using screen-printed gold electrodes (SPGEs) for the sensitive detection of HspX, a latency-associated antigen highly expressed during Mycobacterium tuberculosis dormancy. The aptasensor was fabricated through the immobilization of a thiolated 83-nucleotide DNA aptamer onto electrochemically activated SPGEs via Au–S chemisorption, followed by surface blocking with 6-mercapto-1-hexanol (6-MCH) to reduce non-specific interactions. Potassium ferricyanide/ferrocyanide was used as the redox probe. Cyclic voltammetry (CV) and square wave voltammetry (SWV) analyses confirmed step-wise current reduction at each modification step, indicating successful surface functionalization. Optimization studies identified 3 μM as the optimal aptamer concentration for achieving maximal surface coverage without inducing steric hindrance. The developed aptasensor demonstrated excellent reproducibility, with a relative standard deviation (RSD) of 2.8 % across five independently prepared electrodes. Analytical performance evaluation using recombinant HspX showed a strong linear correlation between SWV peak current reduction and the HspX concentration, resulting in limits of detection of 0.56 ng/mL in buffer and 1.12 ng/mL in spiked serum samples. Despite minor signal attenuation in serum, the sensor maintained high sensitivity and reliability under physiologically relevant conditions. Overall, this study presents a rapid, reproducible, and sensitive electrochemical aptasensor for detecting HspX at diagnostically relevant levels, with strong potential as an affordable, point-of-care diagnostic for LTBI, especially in resource-limited settings.

This study investigates the potential of a protein-DNA aptamer conjugate to enhance aptamer binding to recombinant human intercellular adhesion molecule 1 (rhICAM-1). Aptamers are single-stranded nucleic acids that bind target molecules through hydrogen bonding and hydrophobic interactions. Conjugating aptamers with antibodies or proteins has been shown to improve their binding affinity. Using Systematic Evolution of Ligands by Exponential Enrichment (SELEX), eight rounds of selection were performed with ICAM-1-coupled Dynabeads Protein A, identifying a G/C-rich aptamer, DI05, as having the strongest binding affinity to rhICAM-1. An antibody inhibition assay demonstrated a significant reduction in rhICAM-1 binding to immobilized ap-tamers (DI05, DI20, DI31, and DI33). Additionally, the binding affinity of eGFP-conjugated DI05 to rhICAM-1 was higher than that of unconjugated DI05. Docking simulations revealed close contact between DI05 and ICAM-1, with interactions primarily mediated by hydrogen bonds within three hairpin structures at ≤2.8 Å. These findings highlight the potential of aptamer-small protein conjugates as a promising strategy to enhance aptamer binding characteristics.

Salmonella enterica serovar Typhi (S. Typhi) that has developed resistance to many antimicrobials poses a serious challenge to public health. Hence, this study aimed to systematically determine the prevalence of antimicrobial resistance (AMR) in S. Typhi isolated from the environment and humans as well as to ascertain the spread of the selected AMR genes in S. Typhi. This systematic review and meta-analysis were performed according to the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines, and the study protocol was registered with the International Prospective Register of Systematic Reviews (PROSPERO). A total of 2353 studies were retrieved from three databases, of which 42 studies fulfilled the selection criteria. The pooled prevalence of AMR S. Typhi (using a random-effect model) was estimated at 84.8% (95% CI; 77.3–90.2), with high heterogeneity (I²: 95.35%, p-value < 0.001). The high estimated prevalence indicates that control methods should be improved immediately to prevent the spread of AMR among S. Typhi internationally.

The emergence of nosocomial multidrug-resistant Klebsiella pneumoniae is an escalating public health threat worldwide. The prevalence of nosocomial infections due to K. pneumoniae was recorded up to 10%. In this systematic review and meta-analysis, which were conducted according to the guidelines of Preferred Reporting Items for Systematic Review and Meta-Analysis, 1092 articles were screened from four databases of which 47 studies fulfilled the selected criteria. By performing a random-effect model, the pooled prevalence of nosocomial multidrug-resistant K. pneumoniae was estimated at 32.8% (95% CI, 23.6–43.6), with high heterogeneity (I² 98.29%, p-value < 0.001). The estimated prevalence of this pathogen and a few related studies were discussed, raising awareness of the spread of multidrug-resistant K. pneumoniae in the healthcare setting. The emergence of nosocomial multidrug-resistant K. pneumoniae is expected to increase globally in the future, and the best treatments for treating and preventing this pathogen should be acknowledged by healthcare staff.

Objective: To isolate and characterize RNA aptamers that are specific to human CD36 protein using systematic evolution of ligands by exponential enrichment (SELEX) technology to identify candidates for adjunct therapy to reverse the binding of Plasmodium-infected erythrocytes. Methods: RNA aptamers were isolated using nitrocellulose membrane-based SELEX and binding analysis was screened using an electrophoretic mobility shift assay and enzyme-linked oligonucleotide assay. Results: Thirteen cycles of nitrocellulose membrane-based SELEX yielded three aptamers (RC60, RC25, RC04) exhibiting high binding against CD36 protein as shown on electrophoretic mobility shift assay. The sequence analysis revealed a G-quadruplex sequence within all the isolated aptamers that might contribute to aptamer binding and thermodynamic stability. The specificity assay further showed that RC60 and RC25 were highly specific to CD36. The competitive inhibition assay demonstrated that RC60 and RC25 shared a similar binding epitope recognized by mAb FA6-152, a specific monoclonal antibody against CD36. Conclusions: RC60 and RC25 are promising candidates as anti-cytoadherence for severe malaria adjunct therapy.