Aliyu Danmusa Mohammed, Aliyu Basiru

Antimicrobial Activity of Chemically Modified Anionic Azo Dyes and Their Potential for Treating Infectious Diseases

Introduction

Antimicrobial activity of chemically modified anionic azo dyes and their potential for treating infectious diseases. Discover enhanced antimicrobial activity of modified azo dyes (QAS, AgNPs) against S. aureus and E. coli. Explore their potential for treating infectious diseases, targeting resistant Gram-positive strains.

Abstract

This study explores the synthesis, characterization, and antimicrobial evaluation of quaternary ammonium salts (QAS) and silver nanoparticles (AgNPs) incorporated with azo dyes—Sunset Yellow, Tartrazine, and Allura Red. FTIR spectroscopic studies confirmed key functional groups and interactions, including azo (–N=N), C=C, and hydroxyl stretches, indicating successful conjugation between dyes and carrier materials. The antimicrobial activities of these compounds were assessed against Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, and Salmonella spp. Results revealed enhanced inhibition zones, particularly for the dye incorporated with siver nanoparticles (dye-AgNPs) combinations, with Tartrazine + AgNPs (B2) showing the highest efficacy against S. aureus. Quaternary ammonium salts alone displayed moderate activity, while their combinations with azo dyes yielded improved bacterial inhibition, especially against Gram-positive strains. The enhanced antimicrobial performance is attributed to increased lipophilicity and better penetration of bacterial membranes due to dye incorporation. Furthermore, the research highlights the potential use of azo dye-functionalized QAS and AgNPs as effective antimicrobial agents, especially in targeting resistant Gram-positive pathogens.

Review

This study presents a promising investigation into the antimicrobial potential of chemically modified anionic azo dyes, specifically Sunset Yellow, Tartrazine, and Allura Red, conjugated with quaternary ammonium salts (QAS) and silver nanoparticles (AgNPs). The research outlines a clear methodology involving synthesis, comprehensive FTIR characterization to confirm successful conjugation, and subsequent antimicrobial evaluation against key bacterial pathogens, including *Staphylococcus aureus*, *S. epidermidis*, *Escherichia coli*, and *Salmonella spp*. The reported enhanced inhibition zones, particularly for dye-AgNPs combinations, highlight a significant advance in developing novel antimicrobial agents, offering a valuable contribution to the field of infectious disease treatment. A key strength of this work lies in the clear demonstration of improved antimicrobial activity following dye incorporation, with Tartrazine + AgNPs (B2) exhibiting notably high efficacy against *S. aureus*. The abstract successfully articulates a plausible mechanism for this enhanced performance, attributing it to increased lipophilicity and better penetration of bacterial membranes. This mechanistic insight is crucial for understanding the observed synergistic effects between the dyes and carrier materials. The preferential activity against Gram-positive strains, a group known for increasing antibiotic resistance, underscores the practical relevance and potential clinical impact of these functionalized compounds. While the abstract provides compelling initial findings, a comprehensive review would also consider areas for deeper exploration in the full manuscript. To fully establish the therapeutic potential, a detailed discussion on the compounds' cytotoxicity to host cells is imperative, especially given the known concerns with AgNPs and QAS. Furthermore, a more quantitative assessment of antimicrobial efficacy, such as minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs), would strengthen the comparative analysis. Future directions could also involve investigating the stability of these conjugates in various physiological conditions and expanding the antimicrobial spectrum to include anaerobic bacteria or fungi, ultimately paving the way for *in vivo* studies to validate their clinical utility.

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