Antibacterial Activity of Indolicidin-Coated Silver Nanoparticles in Oral Disease

Carla Zannella,Mariateresa Vitiello,Mariarosaria Boccellino,Annarita Falanga,Marina Di Domenico,Amir Fahmi,Gianluigi Franci,Roberta Gasparro,Surbhi Shinde,Marilena Galdiero,Biagio Santella,Ludovica Nucci,Emilia Galdiero

doi:10.3390/app10051837

Abstract

(1) Background: In dentistry, silver nanoparticles (AgNPs) have progressively earned great interest as antimicrobial drugs and are widely used in several biomedical fields. Recent progress in the analysis of complex bacterial communities has demonstrated the richness of the oral microbiota and the presence of numerous previously unexplained strains. Several efforts have been dedicated to the investigation of antimicrobial peptides (AMPs). Those peptides are a widespread group of small peptides against invading microbes. We report the production of a hybrid molecule composed of AgNPs and indolicidin, a well-known antibacterial peptide. (2) Methods: Spectroscopy and microscopy were used to analyze the optical features and to determine the size of the generated AgNPs. The AgNP antibacterial activity was evaluated versus oral Gram-positive and Gram-negative bacteria. (3) Results: The coated nanoparticles’ antibacterial activity strongly inhibited the growth of microorganisms, with very low minimum inhibitory concentration (MIC) values in the range of 5–12.5 μg/mL. We hypothesize that this effect depended on the specific characteristics of the metal surface coated with indolicidin. The second result was that the coated nanoparticles observed cellular toxicity, was lower with respect to the toxicity of peptide and the naked AgNPs when used individually. (4) New investigations regarding antimicrobial effect of AgNPs coated with AMPs in oral infections are an urgent task.

Highlights

Research in pharmaceutical and biomedicine faces the great challenge of increasing drug resistance, which endlessly forces the research community to implement new therapies [1]
The human oral microbiome database (HOMD) reports more than 700 prokaryotic different species that coexist in the oral cavity that could negatively influence the health of human body and could be involved in the progression of many infections and systemic pathologies [4]
The UV-vis spectra in Figure 2 shows very broad band of aggregated AgNPs prepared in absence of indolicidin, in presence of indolicidin a narrow band appeared at 365 nm

Summary

Introduction

Research in pharmaceutical and biomedicine faces the great challenge of increasing drug resistance, which endlessly forces the research community to implement new therapies [1]. The human oral microbiome database (HOMD) reports more than 700 prokaryotic different species that coexist in the oral cavity that could negatively influence the health of human body and could be involved in the progression of many infections and systemic pathologies [4]. Antibiotics are generally used to tackle the infectious states of the oral cavity, but recently the use of antimicrobial peptides (AMPs) is being considered. AMPs play a protective function by establishing a defense system that may react in a fast and efficient manner [5]. They have a broad-spectrum activity against microorganisms, a low aptitude to induce resistance [6,7], and are excellent candidates for clinical exploitation [8,9]. Two lead examples are the magainin derivative (MSI-78), used as a topical cream for the treatment of foot infections in diabetes [10], and indolicidin (CP-226), used against severe acne and skin infections with Staphylococcus aureus (S. aureus) resistant to methicillin [11]

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Results

Conclusion