Photocleavable antimicrobial peptide mimics for precluding antibiotic resistance

UV-cleavable antimicrobial peptide mimics were synthesized to address environmental accumulation issues.

Hydra amphiphiles: Using three heads and one tail to influence aggregate formation and to kill pathogenic bacteria

Hydra amphiphiles mimic the morphology of the mythical multi-headed creatures for which they are named. Likewise, when faced with a pathogenic bacterium, some hydra derivatives are as destructive as their fabled counterparts were to their adversaries. This report focuses on eight new tricephalic (triple-headed), single-tailed amphiphiles. Each amphiphile has a mesitylene (1,3,5-trimethylbenzene) core, two benzylic trimethylammonium groups and one dimethylalkylammonium group with a linear hydrophobe ranging from short (C₈H₁₇) to ultralong (C₂₂H₄₅). The logarithm of the critical aggregation concentration, log(CAC), decreases linearly with increasing tail length, but with a smaller dependence than that of ionic amphiphiles with fewer head groups. Tail length also affects antibacterial activity; amphiphiles with a linear 18 or 20 carbon atom hydrophobic chain are more effective at killing bacteria than those with shorter or longer chains. Comparison to a recently reported amphiphilic series with three heads and two tails allows for the development of an understanding of the relationship between number of tails and both colloidal and antibacterial properties.

Supramolecular Hydrogelators and Hydrogels: From Soft Matter to Molecular Biomaterials

In this review we intend to provide a relatively comprehensive summary of the work of supramolecular hydrogelators after 2004 and to put emphasis particularly on the applications of supramolecular hydrogels/hydrogelators as molecular biomaterials. After a brief introduction of methods for generating supramolecular hydrogels, we discuss supramolecular hydrogelators on the basis of their categories, such as small organic molecules, coordination complexes, peptides, nucleobases, and saccharides. Following molecular design, we focus on various potential applications of supramolecular hydrogels as molecular biomaterials, classified by their applications in cell cultures, tissue engineering, cell behavior, imaging, and unique applications of hydrogelators. Particularly, we discuss the applications of supramolecular hydrogelators after they form supramolecular assemblies but prior to reaching the critical gelation concentration because this subject is less explored but may hold equally great promise for helping address fundamental questions about the mechanisms or the consequences of the self-assembly of molecules, including low molecular weight ones. Finally, we provide a perspective on supramolecular hydrogelators. We hope that this review will serve as an updated introduction and reference for researchers who are interested in exploring supramolecular hydrogelators as molecular biomaterials for addressing the societal needs at various frontiers.

A zinc complex of a neutral pyridine-based amphiphile: a highly efficient and potentially therapeutic bactericidal material

The complexation of Zn(ii) with a neutral pyridine-based amphiphile generates a potent bactericidal material for potential antibacterial and antibiofilm therapy.

Biocompatible nanocarrier fortified with a dipyridinium-based amphiphile for eradication of biofilm

Annihilation of bacterial biofilms is challenging owing to their formidable resistance to therapeutic antibiotics and thus there is a constant demand for development of potent antibiofilm agents that can abolish established biofilms. In the present study, the activity of a dipyridinium-based cationic amphiphile (compound 1) against established bacterial biofilms and the subsequent development of a compound 1-loaded nanocarrier for potential antibiofilm therapy are highlighted. Solution-based assays and microscopic analysis revealed the antagonistic effect of compound 1 on biofilms formed by Staphylococcus aureus MTCC 96 and Pseudomonas aeruginosa MTCC 2488. In combination studies, compound 1 could efficiently potentiate the action of tobramycin and gentamicin on P. aeruginosa and S. aureus biofilm, respectively. A human serum albumin (HSA)-based nanocarrier loaded with compound 1 was generated, which exhibited sustained release of compound 1 at physiological pH. The compound 1-loaded HSA nanocarrier (C1-HNC) displayed the signature membrane-directed activity of the amphiphile on target bacteria, efficiently eliminated established bacterial biofilms, and was observed to be nontoxic to a model human cell line. Interestingly, compound 1 as well as the amphiphile-loaded HSA nanocarrier could eradicate established S. aureus biofilm from the surface of a Foley's urinary catheter. On the basis of its biocompatibility and high antibiofilm activity, it is conceived that the amphiphile-loaded nanocarrier may hold potential in antibiofilm therapy.

Membrane-directed high bactericidal activity of (gold nanoparticle)-polythiophene composite for niche applications against pathogenic bacteria

The use of nanoscale materials as bactericidal agents represents a novel paradigm in the development of therapeutics against drug-resistant pathogenic bacteria. In this paper the antimicrobial activity of a water soluble (gold nanoparticle)-polythiophene (AuNP-PTh) composite against common bacterial pathogens is reported. The nanocomposite is broad-spectrum in its bactericidal activity and exhibits a membrane-directed mode of action on target pathogens. The therapeutic potency of AuNP-PTh is demonstrated by experiments which reveal that the nanocomposite can breach the outer membrane defense barrier of Gram-negative pathogens for subsequent killing by a hydrophobic antibiotic, inhibit the growth of model gastrointestinal pathogens in simulated gastric fluid, and significantly eradicate bacterial biofilms. The high bacterial selectivity and lack of cytotoxicity on human cells augers well for future therapeutic application of the nanocomposite against clinically relevant pathogenic bacteria.

Retention of nisin activity at elevated pH in an organic acid complex and gold nanoparticle composite

Biocompatible organic acids and citrate-stabilized gold nanoparticles were interacted with nisin to generate robust antimicrobial agents, which display archetypical nisin activity even at elevated pH.