Antimicrobial Efficacy Of Silver Nanoparticles Research Articles

Comparative Evaluation of Antimicrobial Efficacy of Silver Nanoparticles Infused with Azadirachta indica Extract and Chlorhexidine Against Red-complex Pathogens.

The present study aimed to evaluate the antimicrobial efficacy of silver nanoparticles infused with Azadirachta indica extract and chlorhexidine against red-complex periopathogens. Neem leaf extraction was done followed by standardization to the synthesis of neem-infused silver nanoparticles and fractionation of compounds done by using thin layer chromatography to separate the mixture of neem leaf extract. Characterization of neem-infused silver nanoparticles was done by scanning electron microscopy and UV-Visible spectroscopy. The compound identified in neem-infused silver nanoparticles was gedunin which was confirmed by Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. Determination of antibacterial activity done by disc diffusion, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) methods. Group I-99% ethanolic extract, group II-neem-infused silver nanoparticles (NAgNPs), group III-chlorhexidine. The relative inhibitory zone value for Tannerella forsythia (180) in neem-infused silver nanoparticles (group II) was greater when compared with other periopathogens Porphyromonas gingivalis (133) and Treponema denticola (160) than 99% ethanolic extract (group I), chlorhexidine (group III). Neem-infused silver nanoparticles (group III) showed superior antimicrobial activity against T. forsythia (19.3 ± 31.1547) and T. denticola (18±0) when compared with P. gingivalis (17.6 ± 0.5774). On evaluating MIC and minimum bacterial concentrations, P. gingivalis is more resistant than other pathogens in neem-infused silver nanoparticles (group III). Neem-infused silver nanoparticles exhibited superior antibacterial activity as compared with gold-standard chlorhexidine against red-complex periodontal pathogens. For MIC and MBC all the three periopathogens were effective but P. gingivalis was more resistant. Antibiotics are effective against many drug-resistant bacteria. As a ready-made medicine, they can be used to treat many infections. Silver nanoparticles in drug delivery systems generally increase solubility, stability, and biodistribution, thereby increasing their effectiveness. Green synthesis using plant extracts as precursors to synthesize nanoparticles has proven to be environmentally non-hazardous combined with remarkably improved efficacy against bacterial and viral diseases. So neem-infused silver nanoparticles can be utilized as a drug delivery system. Hence, it can be used as a potential antibacterial ingredient in formulations for periodontal use like mouthwashes and gels for local drug delivery. How to cite this article: Krishnappan S, Ravindran S, Balu P, et al. Comparative Evaluation of Antimicrobial Efficacy of Silver Nanoparticles Infused with Azadirachta indica extract and Chlorhexidine Against Red-Complex Pathogens. J Contemp Dent Pract 2024;25(6):547-553.

Green synthesis, characterization and antimicrobial efficacy of silver nanoparticles from Kappaphycus alvarezii extract

Green synthesis, characterization and antimicrobial efficacy of silver nanoparticles from Kappaphycus alvarezii extract

Antimicrobial Activity of Silver Nanoparticles Synthesized Using Ocimum tenuiflorum and Ocimum gratissimum Herbal Formulations.

Background The exploration of green synthesis for silver nanoparticles using diverse plant sources has gained significant attention. This study specifically investigates the use of Ocimum tenuiflorum and Ocimum gratissimum, known for their antibacterial properties, in synthesizing silver nanoparticles. The primary aim of this study is to evaluate the antimicrobial efficacy of silver nanoparticles synthesized using a herbal formulation composed of Ocimum tenuiflorum and Ocimum gratissimumagainst different oral pathogens. Materials and methods The process involved the combination of herbal extracts from Ocimum tenuiflorumand Ocimum gratissimumwith a silver nitrate solution leading to the synthesis of silver nanoparticles. The formation of silver nanoparticles was confirmed by ultraviolet and visible absorption spectroscopy. The obtained silver nanoparticles were used to study their antimicrobial activity. Antimicrobial activity was assessed using the agar well diffusion method against pathogens including Streptococcusmutans, Enterococcus faecalis, C. albicans, Lactobacillus acidophilus, and S. aureus. The zone of inhibition quantified antimicrobial effectiveness. A time-kill curve assay evaluated bactericidal properties and the concentration-dependent relationship between silver nanoparticles and the net growth rate of oral pathogens. Results Statistical analysis was done to compare measures such as mean, standard deviation, and percentages. The antimicrobial assessment demonstrated that 100 μg/mL of silver nanoparticles exhibited the highest efficacy against S. mutans, S. aureus, E. faecalis, and Lactobacillus sp. For C. albicans, all concentrations of silver nanoparticles and the control plant extract displayed similar antimicrobial activity. The time-kill assay illustrated effective inhibition at 100 μg/mL against all tested pathogens, including S. mutans, S. aureus, E. faecalis, C. albicans, and Lactobacillus sp.The result showed positive inhibitory activity of silver nanoparticles against all tested bacterial strains. Conclusion The significant antimicrobial efficacy of green-synthesized silver nanoparticles positions them as promising candidates for dental applications. Their demonstrated bactericidal and fungicidal activities suggest potential use as effective dental antimicrobial agents, opening avenues for innovative solutions in oral healthcare.

Evaluation of Antimicrobial Efficacy of Silver Nanoparticles and Chitosan Nanoparticles against Enterococcus Faecalis and Candida Albicans Biofilm (An in vitro Study)

Evaluation of Antimicrobial Efficacy of Silver Nanoparticles and Chitosan Nanoparticles against Enterococcus Faecalis and Candida Albicans Biofilm (An in vitro Study)

Molecular Profiling, Characterization and Antimicrobial Efficacy of Silver Nanoparticles Synthesized from Calvatia gigantea and Mycena leaiana against Multidrug-Resistant Pathogens.

The use of natural products isolated from mushrooms against infection, cancer diseases and other oxidative-stress-related diseases is one of the cornerstones of modern medicine. Therefore, we tried to establish a combination of medicinal mushrooms and nanotechnology possibly with the field of medicine for the development of antibacterial agents against these MDR strains. The aim of the research was to understand the molecular identification, characterization and antibacterial action of Calvatia gigantea and Mycena leaiana. The identification of fruiting body species via morpho-anatomical and molecular methods was necessary to analyze the genetic variability and phylogenetic relationships of mushrooms. Phylogenetic analysis revealed that Calvatia from Hunza, Pakistan, exhibited 98% resemblance to the previously discovered Langermannia gigantean (DQ112623) and L. gigantean (LN714562) from northern Europe, and Mycena (Pakistan) showed a 97% similarity to M. leaiana (MF686520) and M. leaiana (MW448623) from the USA. UV-vis, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) were used for AgNPs' characterization. The UV-vis absorption peak of 500-600 nm indicates the AgNPs' presence. XRD results determined Calvatia gigantea AgNPs were nanocrystals and Mycena leaiana seems to be amorphous. In addition, SEM results showed the cubic morphology of C. gigantea with a diameter of 65 nm, and the FTIR spectra of fruiting body revealed the presence of functional groups-carboxyl, nitro, and hydroxyl-in AgNPs, which catalyzed the reduction of Ag+ to Ag0. Further antibacterial activity of mushrooms against MDR strains was determined via agar well diffusion assay, and Minimum Inhibitory Concentration (MIC) was estimated by qualitative experimentation using the broth dilution method. All experiments were conducted in triplicate. The results showed that the mushroom AgNPs, along with their synergy and nano-composites (with the exception of Ethyl-acetate), were shown to have zones of inhibition from 4 mm to 29 mm against multidrug-resistant pathogens such as Acinetobacter baumannii, Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumonia, Proteus mirabilis, Enterobacter cloacae and Escherichia coli. The mushroom composites were active against most of the tested microorganisms whilst the lowest MIC value (10-40 mg/mL) was recorded against MDR strains. Hence, the present study suggested the possibility of employing compounds present in mushrooms for the development of new antibacterial agents, as well as efflux pump inhibitors.

Rutin Mediated Synthesis of Silver Nanoparticles derived from Melia dubia and Evaluation of Antioxidant and Antimicrobial Activity

Researches based on bio inspired synthesis of noble metal nano materials has become a promising one in today’s biomedical approach in therapy and diagnosis due to multidimensional applications. Furthermore, silver nanoparticles were reported to have several medicinal applications. Hence the present study was to explore the antioxidant and antimicrobial efficacy of silver nanoparticles (AgNPs) synthesized from rutin isolated from the methanolic extract of leaves of Melia dubia. The biosynthesized nanoparticles were analyzed using UV-Visible, FT-IR, XRD and SEM techniques. The band at 398.5nm in the UV-Visible spectra confirmed the formation of AgNPs. The characteristic shift in OH and C=O peak after the formation of silver nano particles shows the participation of biomaterial (Rutin) in the reduction process which is further supported by SEM report. The average size of the particle (19 nm) was determined from XRD analysis using the Scherrer’s equation. The antimicrobial and antioxidant efficacy of harvested nanoparticles were compared for their potential with rutin and silver salt. The synthesized material was shown to have good antimicrobial activity towards the tested bacteria and fungi and potentially active towards free radicals. Thus, the silver nanoparticles (AgNps) synthesized using bio-flavanoid viz. rutin are potentially good and therefore can be further studied for pharmacological activities.

Antimicrobial Efficacy of Silver Nanoparticles against Candida Albicans.

Current treatment protocols for patients diagnosed with denture stomatitis are under scrutiny, and alternative options are being explored by researchers. The aim of this systematic review was to determine if silver nanoparticles inhibit the growth of Candida albicans, and the research question addressed was: In adults, do silver nanoparticles inhibit the growth of Candida albicans in acrylic dentures and denture liners compared to normal treatment options. A systematic review was the chosen methodology, and criteria were formulated to include all types of studies, including clinical and laboratory designs where the aim was tested. Of the 18 included studies, only one was a clinical trial, and 17 were in vitro research. The inhibition of candidal growth was based on the % concentration of AgNPs included within the denture acrylic and denture liner. As the % AgNPs increased, candida growth was reduced. This was reported as a reduction of candidal colony forming units in the studies. The quality of the included studies was mostly acceptable, as seen from the structured and validated assessments completed.

Microstructure, Mechanical and Antibacterial Properties of TiNb-Based Alloy Implanted by Silver Ions

In this study, in order to obtain an antibacterial property for the TiNb-based alloy, the metal vapor vacuum arc (MEVVA) ion implantation technology was applied to implant the silver on the surface of TiNb-based alloy, which brought the change of the microstructures and mechanical properties for the surface of substrate. It was found that the diffusely distributed silver nanoparticles generated on the outermost surface of the implanted layer and the Ag element exist as a solid-solution state in the implanted layer. Meanwhile, the region of the implanted layer mainly constituted nanocrystalline structures based on the analyses of microstructures. Hence, the nanocrystalline strengthening effect formed by high-energy ion bombardment and the solid solution strengthening effect of silver atoms made contributions to the increase of surface comprehensive mechanical properties, including the surface hardness and elastic modulus. Finally, the suitable Ag-implanted specimen can obtain excellent antibacterial ability. Except for the antibacterial mechanism of silver ions release, the dispersed silver nanoparticles on the surface also provide the contact antimicrobial mechanism, which is the Schottky barrier–dependent antimicrobial efficacy of silver nanoparticles.

Antimicrobial Efficacy of Irreversible Hydrocolloid Impression Impregnated with Silver Nanoparticles Compared to Surface Disinfected Impressions - An In vivo Study.

Background:Routine disinfection procedures have shown to cause incomplete disinfection and detrimental effects on dimensional properties of the impression. Hence, self-disinfecting impression materials impregnated with antimicrobial agents were developed.Purpose:The purpose is to evaluate the antimicrobial efficacy of silver nanoparticles (AgNPs) impregnated in irreversible hydrocolloid (IH) impression material in in vivo conditions.Materials and Methods:This study comprised of four groups-IH impressions disinfected by immersion in 2% glutaraldehyde, IH impregnated with AgNPs of sizes 80–100 nm and 20–30 nm, nondisinfected impressions as control. Five impressions were made for each group and a total of 20 impression samples were made. The antimicrobial action of each sample was assessed by counting the number of colony forming units and by disc diffusion method.Results:The results were obtained and the data were statistically analyzed by Kruskal–Wallis test and tabulated. The results revealed that AgNPs of size 80–100 nm when impregnated in irreversible impression material showed effective antimicrobial action.Conclusion:The anti-microbial action of 80–100 nm AgNP impregnated IH impressions is comparable to that of impressions disinfected by immersion in 2% glutaraldehyde for 10 min.

Antimicrobial Efficacy of Silver Nanoparticles as Root Canal Irrigant's: A Systematic Review.

Removal of microbes is imperative during endodontic therapy. Due to their antimicrobial property, silver nanoparticles have been used for endodontic irrigation of the root canals. The objective of the present study was to provide a qualitative analysis of the published literature assessing silver nanoparticles as root canal irrigants. A search of PubMed, SCOPUS, Web of Science, and Embase databases was done without any time restriction. Articles published in English were included. Data were extracted and the risk of bias was assessed. Of the 154 studies identified, after screening according to the inclusion criteria, five in vitro studies were included. The results indicate that silver nanoparticles have an anti-microbial effect to varying degrees depending on certain factors. Within the limitations of the present studies that have a moderate to low risk of bias, an antimicrobial effect of silver nanoparticles is observed. Silver nanoparticles have the potential to be used as endodontic irrigants, although their efficacy depends on particle size and the duration of contact which require further investigation.

Antimicrobial efficacy of silver nanoparticles against Candida albicans: A systematic review protocol.

Denture-induced stomatitis is one form of candidiasis. It is characterised as inflammation and erythema of the oral mucosa underneath the denture-bearing areas and clinically classified into three types according to severity. Denture hygiene, appropriate mouth rinses and the use of antifungal therapy are commonly used to treat the condition, but new technologies are emerging that may assist in its treatment. The aim of this systematic review is to determine if silver nanoparticles inhibit the growth of Candida Albicans when included in acrylic dentures and in different denture liners. A protocol was developed and published on PROSPERO (Registration No: CRD42019145542) and with the institutional ethics committee (Registration No: BM20/4/1). The protocol includes all aspects of a systematic review namely: selection criteria, search strategy, selection methods using predetermined eligibility criteria, data collection, data extraction, critical appraisal of included studies, and the intended statistical analyses such as calculating risk ratios (RR) for dichotomous outcomes and presented at 95% confidence intervals, a meta-analysis, if possible or a narrative report as needed. With rigorous inclusion criteria set and databases identified for searching, appropriate clinical and laboratory studies may be obtained but the results and its interpretation and translation into clinical practice may be a challenge as these depend on the quality of the research.

“MYCO SYNTHESIS OF SILVER NANOPARTICLES USING GLIOCLADIUM ROSEUM (CLONOSTACHYS ROSEA (LINK) SCHROERS, SAMUELS) AND ITS ANTIMICROBIAL EFFICACY AGAINST SELECTED PATHOGENS”

Objective: Antimicrobial efficacy of silver nanoparticles from Gliocladium roseum, culture filtrate (C. F.) and mycelial mat extract (M. E.) against selected pathogens.
 Methods: Culture filtrate (C. F.) and Mycelial mat extract (M. E.) of Gliocladium roseum were subjected to 10 Mm silver nitrate solution for the synthesis of silver nanoparticles. Formed silver nanoparticles were evaluated via UV-vis spectroscopy and the structural elucidation was done by FT-IR and TEM. Antimicrobial efficacy was tested against bacterial (Salmonella typhi and Klebsiella pneumonia) and fungal (Cladosporium cladosporioides and Alternaria alternata) pathogens. Different nanoparticle concentrations-50, 100, 150 and 200 µl were checked via disc diffusion method.
 Results: Gliocladium roseum (C. F. and M. E.) on interaction with silver nitrate solution effectively reduced metallic silver exhibiting a colour change from yellow to dark brown within 24 h due to the formation of silver nanoparticles. The UV-vis spectrum of C. F. and M. E. showed maximum absorption peaks at 350-400 nm and 400-450 nm respectively and FT-IR and TEM showed strong N-H bonding and spherical shaped silver nanoparticles with the size of 11-19 nm (C. F.) and 25-38 nm (M. E.). Antimicrobial analysis resulted in efficient inhibitory activity against Salmonella typhi, Klebsiella pneumonia and also showed moderate inhibitory activity against Alternaria alternata and Cladosporium cladopsorioides.
 Conclusion: The synthesis of silver nanoparticles from fungus Gliocladium roseum is simple, cheap, safe and eco-friendly thus emphasising on large scale scientific application.

Antimicrobial Efficacy of Silver Nanoparticles Incorporated in an Orthodontic Adhesive: An Animal Study.

Objectives:This study assessed the antimicrobial efficacy of silver nanoparticles (AgNPs) incorporated in Transbond XT orthodontic adhesive used in rats.Materials and Methods:Transbond XT orthodontic adhesive containing 0%, 1%, 5% and 10% AgNPs was experimentally produced. Twenty-eight male Wistar rats were randomly divided into four groups (n=7) of control (0% AgNPs), 1% AgNPs, 5% AgNPs and 10% AgNPs. After anesthetizing the rats, one drop (10 μm) of the adhesive was applied on the central incisor, and light-cured for 20 s. Transbond XT composite (1×1×1 mm) was also applied. Another 10-μm drop was applied over it, and light-cured for 40 s. Biofilm test was carried out, and the number of colony forming units (CFUs) of Streptococcus sanguinis (S. sanguinis), Streptococcus mutans (S. mutans) and Lactobacillus acidophilus (L. acidophilus) in the saliva of rats was counted at baseline and 24 h after the application of adhesive. The data were analyzed using one-way ANOVA and Tukey’s test.Results:In presence of 5% and 10% AgNPs, S. sanguinis and L. acidophilus counts were significantly lower than those in the control and 1% AgNP groups (P<0.05). The S. mutans colony count was significantly lower in presence of all concentrations of AgNPs compared with the control group (P<0.05). The S. mutans colony count in 10% AgNP group was significantly lower than that in 1% and 5% AgNP groups (P<0.05).Conclusion:Silver nanoparticles have dose-dependent antimicrobial effects; 5% concentration is the minimum concentration of AGNPs with optimal antimicrobial efficacy against all strains evaluated in this study.

Cytotoxic and Antimicrobial Efficacy of Silver Nanoparticles Synthesized Using a Traditional Phytoproduct, Asafoetida Gum.

PurposeThe present study synthesized silver nanoparticles (AgNPs) using the aqueous extract of a traditional medicinal product consisting of an oleoresin (a combination of macromolecules of carbohydrates and proteins) exuded from the rhizome of the plant Ferula foetida (asafoetida gum) and evaluated its biological properties.Materials and MethodsThe silver nanoparticles synthesized using asafoetida gum (As-AgNPs) were characterized using UV/Vis spectroscopy, fourier infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD) and transmission electron microscopy (TEM) and EADX. The cytotoxicity and antimicrobial activity As-AgNPs were evaluated against MCF-7 cell lines and selected microbial pathogens, respectively.ResultsThe synthesized silver nanoparticles were crystalline in nature with a spherical shape. The average particle size was 5.6–8.6 nm. The cytotoxicity of the synthesized As-AgNPs was evaluated against MCF-7 cell lines, and the As-AgNPs were found to be effective in inhibiting the multiplication of cancer cells. The As-AgNPs exhibited significant antimicrobial activity towards E. coli, K. pneumoniae and C. albicans. The MIC of the synthesized As-AgNPs was 7.80 μg/mL for E. coli ATCC 25922, Salmonella sp. WS50- and S. typhi; 15.60 μg/mL for S. typhimurium and S. aureus WS10, and 31.20 μg/mL for K. pneumoniae and S. aureus ATCC 43300-MRSA. In addition, MIC values of 15.60 μg/mL for C. albicans ATCC8436 and 31.20 μg/mL for C. krusei ATCC6258 were obtained.ConclusionAs asafoetida is a good traditional medicine, its involvement in the synthesis of AgNPs led the silver nanoparticles to exhibit good cytotoxic and antimicrobial effects.

The synthesis of nano silver-graphene oxide system and its efficacy against endodontic biofilms using a novel tooth model

ObjectiveThe deleterious caustic effects of sodium hypochlorite (NaOCl) as a root canal irrigant makes it imperative that alternative methods are developed for root canal disinfection. The purpose of this study was to examine the antimicrobial efficacy of silver nanoparticles (AgNPs) synthesized on an aqueous graphene oxide (GO) matrix (Ag-GO), with different irrigant delivery methods to enhance the disinfection regimen, using a novel ex vivo infected tooth model. MethodsAgNPs were prepared by reducing AgNO3 with 0.01M NaBH4 in presence of GO. Elemental analysis was performed with scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS) and scanning transmission electron microscopy (STEM) was used for size and morphology analysis of GO and Ag-GO. Nutrient stressed, multi-species biofilms were grown in prepared root canals of single-rooted teeth. The irrigants used were sterile saline, 1% and 2.5% NaOCl, 2% chlorhexidine gluconate (CHX), 17% EDTA and an aqueous suspension of 0.25% Ag-GO. The antimicrobial efficacy of the irrigants were performed with paper point sampling and measurement of microbial counts. The biofilm disruption in dentine tubule surfaces was analysed with confocal laser scanning microscopy (CLSM). The acquisition of total biovolume (μm3/μm2) and biofilm viability was performed using software BioImage_L. Two-way analysis of variance (ANOVA) with post hoc Tukey tests was used for data analysis with level of statistical significance set at P<0.05. ResultsSEM/EDS analysis confirmed impregnation of Ag within the GO matrix. TEM images showed polygonal GO sheets and spherical AgNPs of diameter 20–50nm, forming a network on the surface of GO sheets. The use of ultrasonic activation enhanced the efficacy of Ag-GO compared to 1% NaOCl, 2% CHX, 17% EDTA and sterile saline (P<0.05). The microbial killing efficacy of 2.5% NaOCl was superior compared to the experimental groups. The maximum biofilm disruption, in dentine tubule surfaces, was achieved by 2.5% NaOCl, however Ag-GO caused a significant reduction of total biovolumes compared to the rest of the experimental groups (P<0.05%). SignificanceThe successful documentation of the microbial killing and biofilm disruption capacity of Ag-GO is a promising step forward to explore its unique properties in clinical applications and biomaterials in dentistry.

Antimicrobial efficacy and mechanisms of silver nanoparticles against Phanerochaete chrysosporium in the presence of common electrolytes and humic acid

In this study, influences of cations (Na+, K+, Ca2+, and Mg2+), anions (NO3−, Cl−, and SO42−), and humic acid (HA) on the antimicrobial efficacy of silver nanoparticles (AgNPs)/Ag+ against Phanerochaete chrysosporium were investigated by observing cell viability and total Ag uptake. K+ enhanced the antimicrobial toxicity of AgNPs on P. chrysosporium, while divalent cations decreased the toxicity considerably, with preference of Ca2+ over Mg2+. Impact caused by a combination of monovalent and divalent electrolytes was mainly controlled by divalent cations. Compared to AgNPs, however, Ag+ with the same total Ag content exhibited stronger antimicrobial efficacy towards P. chrysosporium, regardless of the type of electrolytes. Furthermore, HA addition induced greater microbial activity under AgNP stress, possibly originating from stronger affinity of AgNPs over Ag+ to organic matters. The obtained results suggested that antimicrobial efficacy of AgNPs was closely related to water chemistry: addition of divalent electrolytes and HA reduced the opportunities directly for AgNP contact and interaction with cells through formation of aggregates, complexes, and surface coatings, leading to significant toxicity reduction; however, in monovalent electrolytes, the dominating mode of action of AgNPs could be toxic effects of the released Ag+ on microorganisms due to nanoparticle dissolution.

In vitro evaluation of antimicrobial property of silver nanoparticles and chlorhexidine against five different oral pathogenic bacteria

IntroductionNumerous antimicrobial agents are used to eliminate oral biofilm. However due to emergence of multi drug resistant microorganisms, the quest to find out biologically safe and naturally available antimicrobial agents continues. AimTo evaluate antimicrobial efficacy of silver nano-particles against five common oral pathogenic bacteria. ObjectiveTo determine antimicrobial activity of silver nanoparticles and chlorhexidine gluconate against oral pathogenic bacteria. Material and MethodWe used strains of Streptococcus mutans (MTCC 497), Streptococcus oralis (MTCC 2696), Lactobacillus acidophilus (MTCC 10307), Lactobacillus fermentum (MTCC 903), and Candida albicans (MTCC 183). We used commercially available silver nanoparticles (experimental group) and chlorhexidine gluconate (positive control). We determined minimum inhibitory concentration (MIC) minimum bactericidal concentration (MBC) of both agents and analyzed the data using paired ‘t’ test, one way ANOVA and Tucky’s post Hoc HSD. ResultSilver nanoparticles inhibited bacterial growth moderately. The mean MIC of AgNP against S. mutans was 60 ± 22.36 μg/ml, S. oralis – 45 ± 11.18 μg/ml, L. acidophilus – 15 ± 5.59 μg/ml, L. fermentum – 90 ± 22.36 μg/ml, Candida albicans – 2.82 ± 0.68 μg/ml respectively. For chlorhexidine gluconate, mean MIC for S. mutans was 300 ± 111.80 μg/ml, S. oralis – 150 ± 55.90 μg/ml, L. acidophilus – 450 ± 111.80 μg/ml, L. fermentum – 450 ± 111.80 μg/ml and Candida albicans – 150 ± 55.90 μg/ml. MIC and MBC values of AgNP were significantly lower than chlorhexidine gluconate and statistically significant (p < 0.05). ConclusionSilver nanoparticles exhibited better bacteriostatic and bactericidal effect with concentration less than five folds as compared to chlorhexidine. Silver nanoparticles when used in appropriate concentration as safe alternative to present chemically derived other antimicrobial agents.

Comparative Evaluation of Antimicrobial Efficacy of Silver Nanoparticles and 2% Chlorhexidine Gluconate When Used Alone and in Combination Assessed Using Agar Diffusion Method: An In vitro Study.

Context:Silver nanoparticle (AgNP) is a potent antimicrobial that is widely used in several fields of medicine. Chlorhexidine (CHX) gluconate is a well-known agent used in dentistry to eliminate oral microbial flora.Aims:The aim of this study is to evaluate the efficacy of AgNPs, 2% CHX gluconate, and the combination of two solutions against endodontic pathogens such as Enterococcus faecalis, Klebsiella pneumoniae, and Candida albicans. These organisms are frequently found in the root canal space and their persistence may lead to endodontic failure. The synergistic effect of the two solutions has been evaluated in this study. The antibiotic gentamycin was taken as the control group.Settings and Design:Agar well diffusion method was used and minimum inhibitory concentration of AgNP was found to be 15 μg/mL. AgNPs were synthesized from the aqueous plant extract of Cassia roxburghii. The combination of CHX-AgNP solution was stirred together by a glass rod. The values were tabulated and subjected to statistical analysis using the SPSS software version 20. One-way ANOVA test was used to compare within the groups and between groups. The level of significance was set at 5%.Results:CHX-AgNP combined solution exhibited the highest efficacy in comparison to these solutions used alone. They showed the highest efficacy against C. albicans among the three organisms tested.Conclusion:The present study demonstrates the antimicrobial efficacy of a novel mixture of CHX-AgNP solution, and it may be developed as a promising antimicrobial agent against endodontic flora.

Enhanced antimicrobial efficacy of thermal-reduced silver nanoparticles supported by titanium dioxide

The antimicrobial efficacy of silver nanoparticles (AgNPs) is influenced by many factors, including the particle size, AgNP oxidation state and support materials. In this study, AgNPs are synthesized and supported by two types of TiO2 powders (P25 and Merck TiO2) using two heat-treatment temperatures (120 and 200°C). The formation of well-dispersed AgNPs with diameters ranging from 3.2 to 5.7nm was confirmed using transmission electron microscopy. X-ray photoelectron spectroscopy and X-ray diffraction indicated that the majority of the AgNPs were reduced from Ag+ to Ag0 at 200°C. The AgNP antimicrobial activity was determined by the zone of inhibition against three fungi, A. niger, P. spinulosum and S. chartarum, and two bacteria, E. coli (Gram-negative) and S. epidermidis (Gram-positive). The antimicrobial activity of metallic AgNPs was more pronounced than that of silver nitrate and some antimicrobial drugs. The AgNPs exhibited optimal antimicrobial efficacy when the AgNP dispersion on the surface of TiO2 was in the region between 0.2 and 0.7μg-Ag/m2. The minimum (critical) AgNP concentrations needed to inhibit the growth of bacteria (E. coli) and fungi (A. niger) were 13.48 and 25.4μg/mL, respectively. The results indicate that AgNPs/TiO2 nanocomposites are a promising disinfectant against both bacteria and fungi.

Enhanced Cellular Internalization: A Bactericidal Mechanism More Relative to Biogenic Nanoparticles than Chemical Counterparts.

Biogenic synthesis of silver nanoparticles for enhanced antimicrobial activity has gained a lot of momentum making it an urgent need to search for a suitable biocandidate which could be utilized for efficient capping and shaping of silver nanoparticles with enhanced bactericidal activity utilizing its secondary metabolites. Current work illustrates the enhancement of antimicrobial efficacy of silver nanoparticles by reducing and modifying their surface with antimicrobial metabolites of cell free filtrate of Trichoderma viride (MTCC 5661) in comparison to citrate stabilized silver nanoparticles. Nanoparticles were characterized by visual observations, UV-visible spectroscopy, zetasizer, and transmission electron microscopy (TEM). Synthesized particles were monodispersed, spherical in shape and 10-20 nm in size. Presence of metabolites on surface of biosynthesized silver nanoparticles was observed by gas chromatography-mass spectroscopy (GC-MS), energy dispersive X-ray analysis (EDAX), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The antimicrobial activity of both silver nanoparticles was tested against Shigella sonnei, Pseudomonas aeruginosa (Gram-negative) and Staphylococcus aureus (Gram-positive) by growth inhibition curve analysis and colony formation unit assay. Further, it was noted that internalization of biosynthesized nanoparticles inside the bacterial cell was much higher as compared to citrate stabilized particles which in turn lead to higher production of reactive oxygen species. Increase in oxidative stress caused severe damage to bacterial membrane enhancing further uptake of particles and revoking other pathways for bacterial disintegration resulting in complete and rapid death of pathogens as evidenced by fluorescein diacetate/propidium iodide dual staining and TEM. Thus, study reveals that biologically synthesized silver nanoarchitecture coated with antimicrobial metabolites of T. viride was more potent than their chemical counterpart in killing of pathogenic bacteria.