Multicenter evaluation of the Selux Next-Generation Phenotyping antimicrobial susceptibility testing system.

The Selux Next-Generation Phenotyping (NGP) system (Charlestown, MA) is a new antimicrobial susceptibility testing system that utilizes two sequential assays performed on all wells of doubling dilution series to determine MICs. A multicenter evaluation of the performance of the Selux NGP system compared with reference broth microdilution was conducted following FDA recommendations and using FDA-defined breakpoints. A total of 2,488 clinical and challenge isolates were included; gram-negative isolates were tested against 24 antimicrobials, and gram-positive isolates were tested against 15 antimicrobials. Data is provided for all organism-antimicrobial combinations evaluated, including those that did and did not meet FDA performance requirements. Overall very major error and major error rates were less than 1% (31/3,805 and 107/15,606, respectively), essential agreement and categorical agreement were >95%, reproducibility was ≥95%, and the average time-to-result (from time of assay start to time of MIC result) was 5.65 hours.

Microplate-based surface area assay for rapid phenotypic antibiotic susceptibility testing.

Rapid delivery of proper antibiotic therapies to infectious disease patients is essential for improving patient outcomes, decreasing hospital lengths-of-stay, and combating the antibiotic resistance epidemic. Antibiotic stewardship programs are designed to address these issues by coordinating hospital efforts to rapidly deliver the most effective antibiotics for each patient, which requires bacterial identification and antimicrobial susceptibility testing (AST). Despite the clinical need for fast susceptibility testing over a wide range of antibiotics, conventional phenotypic AST requires overnight incubations, and new rapid phenotypic AST platforms restrict the number of antibiotics tested for each patient. Here, we introduce a novel approach to AST based on signal amplification of bacterial surfaces that enables phenotypic AST within 5 hours for non-fastidious bacteria. By binding bacterial surfaces, this novel method allows more accurate measurements of bacterial replication in instances where organisms filament or swell in response to antibiotic exposure. Further, as an endpoint assay performed on standard microplates, this method should enable parallel testing of more antibiotics than is currently possible with available automated systems. This technology has the potential to revolutionize clinical practice by providing rapid and accurate phenotypic AST data for virtually all available antibiotics in a single test.

One-pot polyglycidol nanogels via liposome master templates for dual drug delivery.

Polyglycidol-based nanohydrogels (nHGs) have been prepared by optimizing the use of liposome master templates resulting in a high-yielding and more practical one-pot process to provide materials capable of carrying drugs of adverse chemical nature. The nanogels prepared with the one-pot method showed favorable kinetics for the release of either Nile Red (NR) or lysozyme (LYS), loaded with gel precursors such as semi-branched poly(glycidol allylglycidyl ether), PEG dithiol (1KDa), a free radical initiator and liposomal lipids at the liposome formation step. This process is superior to a comparable step-wise traditional approach and circumvents loading of the gel precursors with the hydrophilic drug into preformed liposome templates. A thiol-ene crosslinking reaction accomplishes the formation of the nanonetwork resulting in nHGs prepared in the traditional step-wise (nHG-SW) approach and the one-pot (nHG-OP) process. Both nanogel networks were characterized in terms of particle size and zeta (ζ) potential with average values of 148nm±39nm and -25.9mV±9.2 for the nHG-SW and 132nm±32 and -23.1mV±9.7 for the nHG-OPs. Loading efficiency for both of the nanogels with NR was determined by spectrophotometry to be 28% (nHP-SW) and 31% (nHP-OP). The LYS loading was based on the target loading of 10µg/mg for both nanogels found to be 84% and 86% for the nHG-SW and nHP-OP, respectively. As proof of concept for combination drug delivery, the in vitro release of both drug mimics, NR and LYS, were monitored under physiologically relevant conditions by an optimized dialysis method. The implementation of the multi-functional and semi-branched polyglycidol is recognized as the main contributor for the observed highly controlled release of proteins that are otherwise rapidly released from common PEG-based nanogel networks. Furthermore, the one-pot process led to be the most favorable drug delivery system based on the release kinetics pointing to a denser polymer network.

Precise Microscale Polymeric Networks through Piezoelectronic Inkjet Printing.

Microsized particles are versatile drug delivery systems with applications as inhalants, implants, and vaccines. An ideal fabrication technique is envisioned to provide particles with controlled size dimensions and is facile, without excessive loss of drug during incorporation, modulated morphologies and release kinetics. In this work, we report on the utilization of a set of polymeric building blocks such as allyl- functionalized polycarbonates, semibranched poly(glycidol allylglycidyl ether)s, and dithiol-PEG cross-linkers to form microsized networks in controlled size dimensions of 18-12 µm, 12-8 µm, and 1-2 µm with modulated morphologies and hydrophilicity based on the ratio of the polycarbonate or polyglycidol building blocks. Piezoelectric ink jet printing allows for the direct printing of these polymeric structures onto substrates, after which the printed droplet is cross-linked via UV light using thiol-ene click reactions. By varying the ratio of the allyl-functionalized building block droplets from being purely prepared either from polycarbonate (PC), polyglycidol (PG) backbones or in a ratio of 70/30 of functionalized polycarbonates and polyglycidols, the droplets can be either printed in DMSO or water. Preliminary studies to control the particle sizes not only through the droplet volume but also by reducing the polymer concentration by 20%, resulted in another set of 70/30 polycarbonate/polyglycidol micron sized networks with an observed corresponding size reduction of 20%. With this, we have developed a facile technique to prepare microsized hydrogel particles with homogeneous and attractive size dimensions that can be directly prepared without using lithography methodologies. The strength of the approach is the set of unique polymeric building blocks that in combination with the new technique allows for a modulation of hydrophilicity and morphologies to form promising drug delivery candidates to carry and release synthetic as well as biological cargo.

Stretchable gas barrier achieved with partially hydrogen-bonded multilayer nanocoating.

Super gas barrier nanocoatings are recently demonstrated by combining polyelectrolytes and clay nanoplatelets with layer-by-layer deposition. These nanobrick wall thin films match or exceed the gas barrier of SiOx and metallized films, but they are relatively stiff and lose barrier with significant stretching (≥ 10% strain). In an effort to impart stretchability, hydrogen-bonding polyglycidol (PGD) layers are added to an electrostatically bonded thin film assembly of polyethylenimine (PEI) and montmorillonite (MMT) clay. The oxygen transmission rate of a 125-nm thick PEI-MMT film increases more than 40x after being stretched 10%, while PGD-PEI-MMT trilayers of the same thickness maintain its gas barrier. This stretchable trilayer system has an OTR three times lower than the PEI-MMT bilayer system after stretching. This report marks the first stretchable high gas barrier thin film, which is potentially useful for applications that require pressurized elastomers.

Controlled branching of polyglycidol and formation of protein-glycidol bioconjugates via a graft-from approach with "PEG-like" arms.

The control of the branching in polyglycidols as semibranched alternatives to traditional polyglycidols is presented. The relative abundance of dendritic carbons is lowered by five-fold compared to hyperbranched polyglycidols. It is the first example of tailoring the branching in polyglycidol and creating protein-glycidol bioconjugates as alternatives to pegylated biostructures.