Search for: All records

Abstract: A colorimetric indicator displacement assay (IDA) amenable to high-throughput experimentation was developed to determine the percentage of cis and trans alkenes. Using 96-well plates two steps are performed: a reaction plate for dihydroxylation of the alkenes followed by an IDA screening plate consisting of an indicator and a boronic acid. The dihydroxylation generates either erythro or threo vicinal diols from cis or trans alkenes, depending upon their syn- or antiaddition mechanisms. Threo diols preferentially associate with the boronic acid due to the creation of more stable boronate esters, thus displacing the indicator to a greater extent. The generality of the protocol was demonstrated using seven sets of cis and trans alkenes. Blind mixtures of cis and trans alkenes were made, resulting in an average error of 2% in the percentage of cis or trans alkenes, and implementing E2 and Wittig reactions gave errors of 3%. Furthermore, we developed variants of the IDA for which the color may be tuned to optimize the response for the human eye. 

Poly(methyl methacrylate) (PMMA) bone cement is used in several biomedical applications including as antibiotic‐filled beads, temporary skeletal spacers, and cement for orthopedic implant fixation. To mitigate infection following surgery, antibiotics are often mixed into bone cement to achieve local delivery. However, since implanted cement is often structural, incorporated antibiotics must not compromise mechanical properties; this limits the selection of compatible antibiotics. Furthermore, antibiotics cannot be added to resolve future infections once cement is implanted. Finally, delivery from cement is suboptimal as incorporated antibiotics exhibit early burst release with most of  the drug remaining permanently trapped. This prolonged subtherapeutic dosage drives pathogen antibiotic resistance. To overcome these limitations of antibiotic‐laden bone cement, insoluble cyclodextrin (CD) microparticles are incorporated into PMMA to provide more sustained delivery of a broader range of drugs, without impacting mechanics. PMMA formulations with and without CD microparticles are synthesized and filled with one of three antibiotics and evaluated using zone of inhibition, drug release, and compression studies. Additionally, the ability of PMMA with microparticles to serve as a refillable antibiotic delivery depot is explored. Findings suggest that addition of CD microparticles to cement promotes postimplantation antibiotic refilling and enables incorporation of previously incompatible antibiotics while preserving favorable mechanical properties.