A bio-based pro-antimicrobial polymer network via degradable acetal linkages

Abstract

With the increasing number of patients prescribed immunosuppressants coupled with the rise in antibiotic resistance - life-threatening microbial infections are a looming global threat. With limited success within the antibiotic pipeline, nature-based essential oils (EOs) are being investigated for their multimodal effectiveness against microbes. Despite the promising potential of EOs, difficulties in their encapsulation, limited water solubility, and high volatility limit their use. Various studies have shown that covalent attachment of these EO derivatives to polymers can mitigate these limitations. The current study presents the synthesis of a fully-degradable, sustained release, cytocompatible, pro-antimicrobial acetal network derived from p-anisaldehyde. This polymer network design provides a pathway toward application-specific EO releasing materials with quantitative encapsulation efficiencies, sustained release, and broad-spectrum antimicrobial activity.

Command-destruct thermosets via photoinduced thiol-catalyzed β-scission of acyclic benzylidene acetals

“…1A). However, application of the thiol-catalyzed process to acyclic benzylidene acetals, such as those employed as building blocks for our previous work, [15][16][17] would result in cleavage of the acetal to the benzoate ester and alkyl group 22 (Fig. 1B) -a process that we postulated could lead to polymer network destruction.…”

“…Sulfur-centered radicals are ubiquitous in many chemical and biological processes 1 and have found broad utility in synthetic polymer chemistry due to their facile formation and inherent reactivity. 2,3 Due to the relatively weak S-H bond (bond dissociation energy 79-87 kcal/mol), 4 thiyl radicals are readily generated by hydrogen atom abstraction of thiols via thermal or photochemical initiation.…”

“…aliphatic alcohols/amines, acetals, etc.). 1 H-abstraction then generates a nucleophilic carboncentered radical that can either be reduced back the starting material by the thiol or engage in additional transformations. Roberts et al exploited the concept of converting electrophilic radicals to nucleophilic radicals using catalytic quantities of thiol as "polarity reversal catalysts" (PRCs) for a broad range of small molecule transformations, 9 including reductions, 10,11 epimerizations, 12 and deoxygenations.…”

“…Building on our recent work with hydrolytically degradable poly(thioether acetal) thermosets, [15][16][17] we were inspired by literature from Roberts et al that used thiols as PRCs for radical-mediated redox of benzylidene acetals to benzoate esters (Fig. 1).…”

Emerging Nanomedicine Therapies to Counter the Rise of Methicillin-Resistant Staphylococcus aureus

“…Using this strategy, the antimicrobial agent p-anisaldehyde (pA) was entrapped in a polymeric mesh that was capable of controlled release under acidic conditions. When released it was observed that the antimicrobial activity of the pA was retained and resulted in significantly improved inhibition of MRSA compared to free drug controls with minimal toxicity observed [ 177 ]. However, it should be noted again, the potential for additional regulatory hurdles that may be associated with chemically binding the active drug to the delivery vector.…”