Green-Synthesized Silver Nanoparticles: Antifungal and Cytotoxic Potential for Further Dental Applications.

Fungal infections caused by Candida albicans (C. albicans) are one of the most prevalent types of oral disorders in the elderly. It has been reported that drug resistance to fungal pathogens poses a severe risk to global healthcare systems and public health. Therefore, the goal of this work is to investigate the cytotoxic and antifungal properties of silver nanoparticles (AgNPs) produced using three different natural extracts: Berzelia lanuginose, Helichrysum cymosum, and Searsia crenata. According to the UV-Vis results, the synthesized AgNPs via B. lanuginose, H. cymosum, and S. crenata show surface plasmonic resonance (SPR) peaks at 430, 440, and 428 nm, respectively. HR-TEM revealed different shapes for the nanoparticles within the size ranges of 16-20, 31-60, and 57-72 nm for B. lanuginose, H. cymosum, and S. crenata, respectively. Using a human oral fibroblast cell line, the cytotoxicity of both AgNPs and plant extracts was tested at concentrations of 0.007, 0.012, 0.025, and 0.062 mg/mL (buccal mucosa fibroblasts). The antifungal activity showed growth inhibition zones of approximately 18 mm, 18.67 mm, and 18.33 mm for the AgNPs conjugated with B. lanuginose, H. cymosum, and S. crenata, respectively. For the studied samples, the minimum inhibitory concentration (MIC50) was less than 0.015 mg/mL. The AgNPs exhibited antifungal activity that was concentration- and size-dependent. The results of this study offer new insights into the cytotoxicity and antifungal activity of the green-synthesized AgNPs.

Prospects of Using Gum Arabic Silver Nanoparticles in Toothpaste to Prevent Dental Caries.

There is growing interest in the use of green synthesized silver nanoparticles (AgNPs) to control and prevent dental diseases. The incorporation of green synthesized AgNPs into dentifrices to reduce pathogenic oral microbes is motivated by their presumed biocompatibility and broad-spectrum antimicrobial activity. In the present study, gum arabic AgNPs (GA-AgNPs) were formulated into a toothpaste (TP) using a commercial TP at a non-active concentration, to produce GA-AgNPs_TP. The TP was selected after evaluating the antimicrobial activity of four commercial TPs 1-4 on selected oral microbes using agar disc diffusion and microdilution assays. The less active TP-1 was then used in the formulation of GA-AgNPs_TP-1; thereafter, the antimicrobial activity of GA-AgNPs_0.4g was compared to GA-AgNPs_TP-1. The cytotoxicity of GA-AgNPs_0.4g and GA-AgNPs_TP-1 was also assessed on the buccal mucosa fibroblast (BMF) cells using the MTT assay. The study demonstrated that antimicrobial activity of GA-AgNPs_0.4g was retained after being combined with a sub-lethal or inactive concentration of TP-1. The non-selective antimicrobial activity and cytotoxicity of both GA-AgNPs_0.4g and GA-AgNPs_TP-1 was demonstrated to be time and concentration dependent. These activities were instant, reducing microbial and BMF cell growth in less than one hour of exposure. However, the use of dentifrice commonly takes 2 min and rinsed off thereafter, which could prevent damage to the oral mucosa. Although, GA-AgNPs_TP-1 has a good prospect as a TP or oral healthcare product, more studies are required to further improve the biocompatibility of this formulation.

Antimicrobial Effects of Gum Arabic-Silver Nanoparticles against Oral Pathogens.

Dental caries is considered one of the most prevalent oral diseases worldwide, with a high rate of morbidity among populations. It is a chronic infectious disease with a multifactorial etiology that leads to the destruction of the dental tissues. Due to their antimicrobial, anti-inflammatory, antifungal, and antioxidant properties; silver nanoparticles (AgNPs) are incorporated in dental products to help prevent infectious oral diseases. In this study, the antimicrobial effects of AgNPs synthesized using Gum Arabic extracts (GAE) were examined. The GA-AgNPs were synthesized and characterized using ultraviolet-visible (UV-Vis) spectrophotometer, dynamic light scattering (DLS), transmission electron microscopy (TEM), and Fourier transform infrared (FTIR) spectroscopy. The antimicrobial activity of the GA-AgNPs was evaluated on Streptococcus sanguinis (S. sanguinis), Streptococcus mutans (S. mutans), Lactobacillus acidophilus (L. acidophilus), and Candida albicans (C. albicans) using agar disc diffusion and microdilution assays. The antibiofilm of GA-AgNPs was evaluated on the surface of human tooth enamel that had been exposed to S. mutans with and without the GA-AgNPs using scanning electron microscopy (SEM). GA-AgNPs were spherical in shape with a particle size distribution between 4 and 26 nm. The GA-AgNPs exhibited antimicrobial activity against all the tested oral microbes, with GA-AgNPs_0.4g having higher antimicrobial activity. The GA-AgNPs_0.4g inhibited S. mutans adhesion and biofilm formation on the surface of the tooth enamel. Therefore, this study supports the prospective implementation of the plant extract-mediated AgNPs in dental healthcare.

Plant Extract-Synthesized Silver Nanoparticles for Application in Dental Therapy.

Oral diseases are the most common non-communicable diseases in the world, with dental caries and periodontitis causing major health and social problems. These diseases can progress to systematic diseases and cause disfigurement when left untreated. However, treatment of oral diseases is among the most expensive treatments and often focus on restoration of form and function. Caries prevention has traditionally relied on oral hygiene and diet control, among other preventive measures. In this paper, these measures are not disqualified but are brought into a new context through the use of nanotechnology-based materials to improve these conventional therapeutic and preventive measures. Among inorganic nanomaterials, silver nanoparticles (AgNPs) have shown promising outcomes in dental therapy, due to their unique physicochemical properties and enhanced anti-bacterial activities. As such, AgNPs may provide newer strategies for treatment and prevention of dental infections. However, numerous concerns around the chemical synthesis of nanomaterials, which are not limited to cost and use of toxic reducing agents, have been raised. This has inspired the green synthesis route, which uses natural products as reducing agents. The biogenic AgNPs were reported to be biocompatible and environmentally friendly when compared to the chemically-synthesized AgNPs. As such, plant-synthesized AgNPs can be used as antimicrobial, antifouling, and remineralizing agents for management and treatment of dental infections and diseases.

Antimicrobial and cytotoxic activity of electrosprayed chitosan nanoparticles against endodontic pathogens and Balb/c 3T3 fibroblast cells.

The aims of this study were to synthesize highly positively charged chitosan nanoparticles (Ch-Np) using the electrospraying technique, and to test their antimicrobial activity against endodontic pathogens, and cytotoxicity against fibroblast cells. Ch-Np were synthesized from low molecular weight chitosan (LMW-Ch) using the electrospraying technique, and characterized. The antimicrobial activity was evaluated against Streptococcus mutans, Enterococcus faecalis, and Candida albicans in their planktonic state using a Time-Kill Test performed by using broth micro-dilution technique, and against biofilm biomass using a microtiter plate biofilm assay. The cytotoxicity was evaluated using Balb/c 3T3 fibroblast cells with the standard MTT assay. Electrospraying of LMW-Ch produced Ch-Np with an average size of 200 nm, and a surface charge of 51.7 mV. Ch-Np completely eradicated S. mutans and E. faecalis in the planktonic state and showed fungistatic activity against C. albicans. Furthermore, it significantly reduced the biofilm biomass for all the tested microbial species [S. mutans (p = 0.006), E. faecalis (p < 0.0001), and C. albicans (p = 0.004)]. When tested for cytotoxicity using 3T3 cells, Ch-Np showed no cytotoxicity. In conclusion, the highly positively charged, colloidal dispersion of Ch-Np are effective as a biocompatible endodontic antimicrobial agent.

Streptococcus mutans Growth and Resultant Material Surface Roughness on Modified Glass Ionomers.

The present study investigate the optical density of Streptococcus mutans (S. mutans) at 450 nm (OD450 nm) as well as the change in surface roughness of three commercially available chitosan- and nanodiamond-modified glass ionomers. The results indicated that the optical density of S. mutans OD450 nm decreased significantly (p < 0.0001) from 0 h through 2-4 h for each of the control materials. The lowest S. mutans OD450 nm was noted for Fuji IX followed by Ketac Universal. Riva Self Cure had the largest increase in the S. mutans OD450 nm. The control materials and their chitosan/nanodiamond modifications showed significant growth at 6 h compare to the preceding time periods of 2 and 4 h. The materials Fuji IX, Fuji IX modified with 5% Nanodiamonds, Fuji IX modified with 10% Chitosan and Ketac Universal modified with 10% Chitosan performed the best with regard to the bacterial reduction. Only the chitosan modifications showed an increase in the surface roughness after 24 h of exposure to the S. mutans. The chitosan and the nanodiamond modifications provided the best disruption of the S. mutans biofilm formation.