Antimicrobial Susceptibility Assays Based on the Quantification of Bacterial Lipopolysaccharides via a Label Free Lectin Biosensor

A label free lectin biosensor developed in our laboratory that can quantitatively measure the binding between the lectin immobilized at the carbohydrate sensor surface and the lipopolysaccharide (LPS) on Gram-negative bacteria was demonstrated for an antibiotic susceptibility assay. The biosensor utilizes a polythiophene interface containing fused quinone moieties glycosylated to form a carbohydrate platform for the immobilization of Concanavalin A (Con A) and is capable of LPS binding measurements via orthogonal quartz crystal microbalance and electrochemical readouts (EQCM). Such orthogonal transduction provides cross-validation, better sensor sensitivity, and a large dynamic range of the measurements. We have applied this label free lectin biosensor for a new antibiotic susceptibility assay by characterizing the antimicrobial activities of various antibiotics (i.e., ciprofloxacin, ceftriaxone, and tetracycline) against Escherichia coli W1485 as a model system. The label free biosensor allows both end point and real time measurements of antibiotic effects on the bacterial cell surface LPS, which is shown to correlate to their antibiotic effects. At the end point, after 18 h incubation of bacterial cells with these three antibiotics respectively, the bacterial LPS binding signal was reduced to 23%, 27%, and 38%, respectively, for the three antibiotics, indicating that ciprofloxacin is the most effective against this E. coli strain. Real time measurements at the 1 h time point showed a similar trend with a reduction of binding to 91%, 93%, and 95%, respectively. From the binding kinetics of these measurements, the relaxation time (τ) was obtained, where higher τ value means slow binding interactions between the lectin and the bacterial LPS. The obtained order of τ, (i.e., τ_{ciprofloxacin} > τ_ceftriaxone > τ_tetracycline) again indicated that ciprofloxacin has more bactericidal activity than the other two antibiotics with the same concentrations. Thus, we are able to establish that the reduction in the binding of LPS with the lectin Con A sensor upon exposure to various antibiotics has a direct relation with the antibiotic dosages making this label free biosensor assay promising for therapeutic management of these drugs as well as for applications in antibiotic research and development

Additional file 1: Table S1. of Do emergency medicine journals promote trial registration and adherence to reporting guidelines? A survey of “Instructions for Authors”

Journal selection, with exclusions. (DOCX 13 kb

In Nanoconfined Environments, Larger Ions in the Electrolyte Influence the Local Proton Availability for the Oxygen Reduction Reaction

The impact of the electrolyte ion size on electrocatalytic reactions that occur within nanoconfined volumes is currently unknown. Herein, the effect of the size of solvated alkali metal ions on the oxygen reduction reaction (ORR) in acidic electrolytes was explored by using nanoparticles that contain isolated Pt nanochannels of 1–2 nm in diameter. The exterior surface of the nanoparticles was passivated to ensure that the ORR occurred only in the nanoconfined volume defined by the nanochannels. A number of alkali metal ions, with different hydrated sizes, were added into the acidic electrolyte, and different electrolyte ionic strengths were used to establish different levels of nanoconfinement. The results show that the ORR activity at comparatively positive applied potentials is not affected by the presence and nature of the alkali metal ions in the electrolyte. At less positive potentials, however, the activity is influenced by the presence of alkali metal ions in the electrolyte, and this is dependent on both the identity of the alkali metal ions and the electrolyte ionic strength. The differences in activities at less positive potentials are attributed to differences in the alkali metal ions’ accessibility to the nanoconfined space with Li+ being accessible and decreasing the electrocatalytic activity relative to inaccessible K+ ions that cannot enter the nanoconfined channels. This was corroborated by molecular dynamics modeling suggesting that the energy penalty for the alkali metal ions to enter the nanochannels is different for the different alkali metal ions and is affected by the surface charge of the nanochannel walls

sj-docx-2-jic-10.1177_08850666231155822 - Supplemental material for A Propensity-Matched Cohort Assessing Impact of a Neutralizing Monoclonal Antibody in Mild-to-Moderate Coronavirus Disease 2019

Supplemental material, sj-docx-2-jic-10.1177_08850666231155822 for A Propensity-Matched Cohort Assessing Impact of a Neutralizing Monoclonal Antibody in Mild-to-Moderate Coronavirus Disease 2019 by Malak Abbas, Nada Farhat, Zainab Hammoud, Curtis Dickey, Ali Shuayto and Nai-Wei Chen, Lama M Hsaiky, Matthew Sims, David Sengstock, Joseph Schramski, Zafar Shamoon in Journal of Intensive Care Medicine</p

sj-docx-1-jic-10.1177_08850666231155822 - Supplemental material for A Propensity-Matched Cohort Assessing Impact of a Neutralizing Monoclonal Antibody in Mild-to-Moderate Coronavirus Disease 2019

Supplemental material, sj-docx-1-jic-10.1177_08850666231155822 for A Propensity-Matched Cohort Assessing Impact of a Neutralizing Monoclonal Antibody in Mild-to-Moderate Coronavirus Disease 2019 by Malak Abbas, Nada Farhat, Zainab Hammoud, Curtis Dickey, Ali Shuayto and Nai-Wei Chen, Lama M Hsaiky, Matthew Sims, David Sengstock, Joseph Schramski, Zafar Shamoon in Journal of Intensive Care Medicine</p

Additional file 1: of An open-label, pragmatic, randomized controlled clinical trial to evaluate the comparative effectiveness of daptomycin versus vancomycin for the treatment of complicated skin and skin structure infection

Daptomycin Pragmatic Skin Trial IRB and Participating Center List. (DOCX 18 kb