Suspension Bead Array of the Single-Stranded Multiplex Polymerase Chain Reaction Amplicons for Enhanced Identification and Quantification of Multiple Pathogens

Detection of respiratory pathogenic bacterial nucleic acid detection by Loop-mediated Isothermal Amplification in patients with bacterial pulmonary infections

Objective

Nucleic acid testing can accurately and rapidly identify the presence of pathogenic bacteria. In this study, we analyzed respiratory pathogenic bacteria nucleic acids by LAMP (Loop-mediated isothermal amplification) to clarify the clinical application in patients with bacterial pulmonary infections.

Methods

Clinical data and specimens were collected from 99 patients with bacterial pulmonary infections from June 2021 to April 2023. We compared the differences between nucleic acid detection of LAMP and sputum culture. The correlation between inflammation manifestations of pulmonary imaging and the nucleic acid detection of LAMP was compared and analyzed. And the relationship between LAMP and blood inflammatory markers were analyzed.

Results

The positive rate of LAMP using sputum specimens was significantly higher than that of sputum culture (P < 0.05). Pathogenic bacteria in sputum samples are more likely to be detected by LAMP in patients with inflammatory on lung imaging examination. The coincidence rate of elevated PCT and CRP expression with positive LAMP results were 83.87 % and 88.71 %, respectively. Moreover, PCT, CRP and WBC were significantly higher in LAMP positive group than those in negative group (P < 0.05).

Conclusion

Nucleic acid testing of sputum specimens for pathogenic bacteria by LAMP on the basis of imaging examination can provide a rapid and accurate experimental basis for clinical diagnosis of bacterial pulmonary infections.

Specific lateral flow detection of isothermal nucleic acid amplicons for accurate point-of-care testing

For point-of-care testing (POCT), coupling isothermal nucleic acid amplification schemes (e.g., recombinase polymerase amplification, RPA) with lateral flow assay (LFA) readout is an ideal platform, since such integration offers both high sensitivity and deployability. However, isothermal schemes typically suffers from non-specific amplification, which is difficult to be differentiated by LFA and thus results in false-positives. Here, we proposed an accurate POCT platform by specific recognition of target amplicons with peptide nucleic acid (PNA, assisted by T7 Exonuclease), which could be directly plugged into the existing RPA kits and commercial LFA test strips. With SARS-CoV-2 as the model, the proposed method (RPA-TeaPNA-LFA) efficiently eliminated the false-positives, exhibiting a lowest detection concentration of 6.7 copies/μL of RNA and 90 copies/μL of virus. Using dual-gene (orf1ab and N genes of SARS-CoV-2) as the targets, RPA-TeaPNA-LFA offered a high specificity (100%) and sensitivity (RT-PCR Ct < 31, 100%; Ct < 40, 71.4%), and is valuable for on-site screening or self-testing during isolation. In addition, the dual test lines in the test strips were successfully explored for simultaneous detection of SARS-CoV-2 and H1N1, showing great potential in response to future pathogen-based pandemics.

Suspension arrays based on nanoparticle-encoded microspheres for high-throughput multiplexed detection

Spectrometrically or optically encoded microsphere based suspension array technology (SAT) is applicable to the high-throughput, simultaneous detection of multiple analytes within a small, single sample volume. Thanks to the rapid development of nanotechnology, tremendous progress has been made in the multiplexed detecting capability, sensitivity, and photostability of suspension arrays. In this review, we first focus on the current stock of nanoparticle-based barcodes as well as the manufacturing technologies required for their production. We then move on to discuss all existing barcode-based bioanalysis patterns, including the various labels used in suspension arrays, label-free platforms, signal amplification methods, and fluorescence resonance energy transfer (FRET)-based platforms. We then introduce automatic platforms for suspension arrays that use superparamagnetic nanoparticle-based microspheres. Finally, we summarize the current challenges and their proposed solutions, which are centered on improving encoding capacities, alternative probe possibilities, nonspecificity suppression, directional immobilization, and "point of care" platforms. Throughout this review, we aim to provide a comprehensive guide for the design of suspension arrays, with the goal of improving their performance in areas such as multiplexing capacity, throughput, sensitivity, and cost effectiveness. We hope that our summary on the state-of-the-art development of these arrays, our commentary on future challenges, and some proposed avenues for further advances will help drive the development of suspension array technology and its related fields.

Fast and sensitive detection of an anthrax biomarker using SERS-based solenoid microfluidic sensor

We report the application of a fully automated surface-enhanced Raman scattering (SERS)-based solenoid-embedded microfluidic device to the quantitative and sensitive detection of anthrax biomarker poly-γ-D-glutamic acid (PGA) in solution. Analysis is based on the competitive reaction between PGA and PGA-conjugated gold nanoparticles with anti-PGA-immobilized magnetic beads within a microfluidic environment. Magnetic immunocomplexes are trapped by yoke-type solenoids embedded within the device, and their SERS signals were directly measured and analyzed. To improve the accuracy of measurement process, external standard values for PGA-free serum were also measured through use of a control channel. This additional measurement greatly improves the reliability of the assay by minimizing the influence of extraneous experimental variables. The limit of detection (LOD) of PGA in serum, determined by our SERS-based microfluidic sensor, is estimated to be 100 pg/mL. We believe that the defined method represents a valuable analytical tool for the detection of anthrax-related aqueous samples.

Recent Advances in Burkholderia mallei and B. pseudomallei Research

Burkholderia mallei and Burkholderia pseudomallei are Gram-negative organisms, which are etiological agents of glanders and melioidosis, respectively. Although only B. pseudomallei is responsible for a significant number of human cases, both organisms are classified as Tier 1 Select Agents and their diseases lack effective diagnosis and treatment. Despite a recent resurgence in research pertaining to these organisms, there are still a number of knowledge gaps. This article summarizes the latest research progress in the fields of B. mallei and B. pseudomallei pathogenesis, vaccines, and diagnostics.