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

A narrative review on application of metal and metal oxide nanoparticles in endodontics

The distinct physicochemical and biological characteristics of metal and metal oxide nanoparticles have attracted considerable interest in various branches of dentistry as potential solutions to the problems associated with conventional dental treatments and to promote human health. Many scientists have been interested in nanoparticles for endodontic applications in the last several decades. Endodontic treatment is more likely to be successful when metal and metal oxide nanoparticles are used. Endodontic therapies often make use of nanoparticles made of metals and metal oxides. The effect of nano metals and metal oxide in endodontic treatments has not been published or is not widely available in the literature. Therefore, this paper aims to review recent studies on the development and application of some important metal and metal oxide nanoparticles such as silver and silver oxide, zinc oxide, zirconium oxide, magnesium oxide, titanium dioxide and other metal oxide nanoparticles in endodontic therapeutic procedures.

Synthesis of Silver Nanoparticles Using Azadirachta indica and Syzygium aromaticum Extract and Its Antibacterial Action Against Enterococcus faecalis: An In Vitro Study

Introduction Nanotechnology is the study of manipulating matter at the atomic scale involving particles smaller than 100 nm. Silver nanoparticles (AgNPs) are gaining popularity across diverse sectors including medical, food, healthcare, consumer goods, and industrial fields due to their distinctive physical and chemical characteristics. The eco-friendly synthesis of AgNPs offers a straightforward, cost-effective, and environmentally benign method devoid of hazardous chemicals. Methodology Eighty milliliters (mL) of silver nitrate mixed with 20 mL of Azadirachta indica and Syzygium aromaticum plant extract underwent two days of magnetic stirring for AgNP synthesis. Characterization was done via ultraviolet-visible (UV-vis)-spectroscopy (300-700 nm), and antimicrobial properties, which were checked with Enterococcus faecalis, were assessed using the agar-well diffusion method. Results The change in color and peak observed in the UV-vis spectrum confirmed the successful synthesis of AgNPs. Both neem and clove extract-mediated synthesis of AgNPs exhibited antibacterial activity against E. faecalis. However, neem extract synthesized AgNPs displayed a larger inhibitory zone diameter and lower minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values compared to those synthesized using clove extract. Conclusion Incorporating neem and clove extracts in AgNP synthesis offers a practical, eco-friendly, and cost-efficient method with notable efficacy. These AgNPs exhibit antibacterial activity against E. faecalis, suggesting their viability as potent antibacterial agents for addressing oral pathogens. Their sustainable synthesis underscores a promising avenue for developing effective antimicrobial solutions in oral healthcare.

Evaluating the antibacterial effect of meropenem-loaded chitosan/sodium tripolyphosphate (TPP) nanoparticles on Acinetobacter baumannii isolated from hospitalized patients

BACKGROUND

Acinetobacter baumannii is a health threat due to its antibiotic resistance. Herein, antibiotic susceptibility and its association with the Toxin-antitoxin (TA) system genes in A. baumannii clinical isolates from Iran were investigated. Next, we prepared meropenem-loaded chitosan nanoparticles (MP-CS) and investigated their antibacterial effects against meropenem-susceptible bacterial isolates.

METHODS

Out of 240 clinical specimens, 60 A. baumannii isolates were assessed. Antibiotic resistance of the isolates against conventional antibiotics was determined alongside investigating the presence of three TA system genes (mazEF, relBE, and higBA). Chitosan nanoparticles were characterized in terms of size, zeta potential, encapsulation efficiency, and meropenem release activity. Their antibacterial effects were assessed using the well diffusion method, minimum inhibitory concentration (MIC), and colony-forming unit (CFU) counting. Their cytotoxic effects and biocompatibility index were determined via the MTT, LDH, and ROS formation assays.

RESULTS

Ampicillin, ceftazidime, and colistin were the least effective, and amikacin and tobramycin were the most effective antibiotics. Out of the 60 isolates, 10 (16.7%), 5 (8.3%), and 45 (75%) were multidrug-resistant (MDR), extensively drug-resistant (XDR), and pandrug-resistant (PDR), respectively. TA system genes had no significant effect on antibiotic resistance. MP-CS nanoparticles demonstrated an average size of 191.5 and zeta potential of 27.3 mV alongside a maximum encapsulation efficiency of 88.32% and release rate of 69.57%. MP-CS nanoparticles mediated similar antibacterial effects, as compared with free meropenem, against the A. baumannii isolates with significantly lower levels of meropenem. MP-CS nanoparticles remarkably prevented A549 and NCI-H292 cell infection by the A. baumannii isolates alongside demonstrating a favorable biocompatibility index.

CONCLUSION

Antibiotic-loaded nanoparticles should be further designed and investigated to increase their antibacterial effect against A. baumannii and assess their safety and applicability in vivo settings.

Lactoferrin/pectin nanocomplex encapsulating ciprofloxacin and naringin as a lung targeting antibacterial nanoplatform with oxidative stress alleviating effect

Pseudomonas aeruginosa is an opportunistic Gram-negative bacterium with adaptive metabolic abilities. It can cause hospital-acquired infections with significant mortality rates, particularly in people with already existing medical conditions. Its ability to develop resistance to common antibiotics makes managing this type of infections very challenging. Furthermore, oxidative stress is a common consequence of bacterial infection and antibiotic therapy, due to formation of reactive oxygen species (ROS) during their mode of action. In this study we aimed to alleviate oxidative stress and enhance the antibacterial efficacy of ciprofloxacin (CPR) antibiotic by its co-encapsulation with naringin (NAR) within a polyelectrolyte complex (PEX). The PEX comprised of polycationic lactoferrin (LF) and polyanionic pectin (PEC). CPR/NAR-loaded PEX exhibited spherical shape with particle size of 237 ± 3.5 nm, negatively charged zeta potential (-23 ± 2.2 mV) and EE% of 61.2 ± 4.9 for CPR and 76.2 ± 3.4 % for NAR. The LF/PEC complex showed prolonged sequential release profile of CPR to limit bacterial expansion, followed by slow liberation of NAR, which mitigates excess ROS produced by CPR's mechanism of action without affecting its efficacy. Interestingly, this PEX demonstrated good hemocompatibility with no significant in vivo toxicity regarding hepatic and renal functions. In addition, infected mice administrated this nanoplatform intravenously exhibited significant CFU reduction in the lungs and kidneys, along with reduced immunoreactivity against myeloperoxidase. Moreover, this PEX was found to reduce the lungs´ oxidative stress via increasing both glutathione (GSH) and catalase (CAT) levels while lowering malondialdehyde (MDA). In conclusion, CPR/NAR-loaded PEX can offer a promising targeted lung delivery strategy while enhancing the therapeutic outcomes of CPR with reduced oxidative stress.

Spray-Dried Mucoadhesive Re-dispersible Gargle of Chlorhexidine for Improved Response Against Throat Infection: Formulation Development, In Vitro and In Vivo Evaluation

Drug delivery to the buccal mucosa is one of the most convenient ways to treat common mouth problems. Here, we propose a spray-dried re-dispersible mucoadhesive controlled release gargle formulation to improve the efficacy of chlorhexidine. The present investigation portrays an approach to get stable and free-flowing spray-dried porous aggregates of chlorhexidine-loaded sodium alginate nanoparticles. The ionic gelation technique aided with the chlorhexidine's positive surface charge-based crosslinking, followed by spray drying of the nanoparticle's dispersion in the presence of lactose- and leucine-yielded nano-aggregates with good flow properties and with a size range of about 120-350 nm. Provided with the high entrapment efficiency (87%), the particles showed sustained drug release behaviors over a duration of 10 h, where 87% of the released drug got permeated within 12 h. The antimicrobial activity of the prepared formulation was tested on S. aureus, provided with a higher zone of growth inhibition than the marketed formulation. Aided with an appropriate mucoadhesive strength, this product exhibited extended retention of nanoparticles in the throat region, as shown by in vivo imaging results. In conclusion, the technology, provided with high drug retention and extended effect, could be a potential candidate for treating several types of throat infections.

Macrofungal Mediated Biosynthesis of Silver Nanoparticles and Evaluation of Its Antibacterial and Wound-Healing Efficacy

Recently, the utilization of biological agents in the green synthesis of nanoparticles has been given interest. In this study, silver nanoparticles were synthesized from an aqueous extract of macrofungus (mushroom), namely Phellinus adamantinus, in a dark room using 20 µL of silver nitrate. Biosynthesized silver nanoparticles were confirmed by analyzing them using a UV-Vis (ultraviolet-visible) spectrophotometer. The synthesized silver nanoparticles were optimized at different pH and temperatures with various dosages of AgNO3 (silver nitrate) and fungal extracts. The synthesized AgNPs (silver nanoparticles) were characterized using TEM (transmission electron microscopy) and EDX (energy-dispersive X-ray) analyses, which confirmed the presence of silver nanoparticles. The size of the nanosilver particles was found to be 50 nm with higher stability. The mycosynthesized AgNPs showed effective antibacterial activity against strains of Gram-positive (Staphylococcus aureus and Bacillus subtilis) and Gram-negative (E. coli and Pseudomonas aeruginosa) bacteria. The minimum inhibitory concentration (MIC) was found to be 3.125 μg/mL by MIC assay. The MTT assay (3-[4,5-dimethylthiazol-2-yl] 2,5-diphenyl-2H-tetrazolium bromide) was performed to study cytotoxicity, and reduced cell viability was recorded at 100 μg/mL. Silver-Polygalacturonic acid-Polyvinyl alcohol ((Ag-PGA)-PVA) nanofiber was prepared using the electrospinning method. The in vitro wound scratch assay was demonstrated to study the wound-healing efficacy of the prepared nanofiber. The wound-healing efficacy of the AgNP-incorporated nanofiber was found to be 20% after 24 h. This study will lay a platform to establish a unique route to the development of a novel nanobiomaterial and its application in antibacterial and wound-healing therapy.

Nanoparticles and Their Antibacterial Application in Endodontics

Root canal treatment represents a significant challenge as current cleaning and disinfection methodologies fail to remove persistent bacterial biofilms within the intricate anatomical structures. Recently, the field of nanotechnology has emerged as a promising frontier with numerous biomedical applications. Among the most notable contributions of nanotechnology are nanoparticles, which possess antimicrobial, antifungal, and antiviral properties. Nanoparticles cause the destructuring of bacterial walls, increasing the permeability of the cell membrane, stimulating the generation of reactive oxygen species, and interrupting the replication of deoxyribonucleic acid through the controlled release of ions. Thus, they could revolutionize endodontics, obtaining superior results and guaranteeing a promising short- and long-term prognosis. Therefore, chitosan, silver, graphene, poly(lactic) co-glycolic acid, bioactive glass, mesoporous calcium silicate, hydroxyapatite, zirconia, glucose oxidase magnetic, copper, and zinc oxide nanoparticles in endodontic therapy have been investigated in the present review. The diversified antimicrobial mechanisms of action, the numerous applications, and the high degree of clinical safety could encourage the scientific community to adopt nanoparticles as potential drugs for the treatment of endodontic diseases, overcoming the limitations related to antibiotic resistance and eradication of the biofilm.

Antibacterial potential of silver nanoparticles (SP-AgNPs) synthesized from Syzygium polyanthum (Wight) Walp. against selected foodborne pathogens

Foodborne diseases continue to pose a significant global health concern, causing a considerable number of deaths worldwide. In response to concerns surrounding bacterial resistance and the limitations of traditional antibiotics, there is a growing interest in exploring natural antibacterial agents as potential alternatives for addressing foodborne pathogens. Nowadays efforts are being made on exploring the potential of natural antibacterial agents against foodborne pathogens. In this study, the antibacterial efficacy of silver nanoparticles synthesized using S. polyanthum leaves extract (SP-AgNPs) against selected Gram-negative and Gram-positive foodborne pathogens was investigated by using multiple assays, including the well diffusion assay (WDA), minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and time-kill assay. The well diffusion assay demonstrated the inhibitory potential of SP-AgNPs against all tested foodborne pathogens, with inhibition zones ranging from 10.16 + 1.25 to 13.16 + 1.52 mm. Furthermore, the MIC values ranged from 0.008 to 0.125 mg/mL, indicating the potent antibacterial activity of SP-AgNPs across a broad spectrum of foodborne pathogens. The MBC values, ranging from 0.008 to 0.250 mg/mL, further confirming the bactericidal ability of SP-AgNPs against these pathogens. In the time-kill experiment, most foodborne pathogens were entirely killed after 4 h of incubation at 4 × MIC concentration. However, only E. coli, K. pneumoniae, and S. Typhimurium showed a reduction in population to 3 Log10 CFU/mL, indicating a strong bactericidal effect of SP-AgNPs on most tested pathogens. In conclusion, this study provides compelling evidence that SP-AgNPs exhibit potent antibacterial activity against selected foodborne pathogens. The findings suggest that SP-AgNPs synthesized using S. polyanthum leaves extract hold great promise as a novel antibacterial agent for effectively controlling foodborne pathogens. These findings contribute to continuing efforts in developing alternative strategies to prevent foodborne diseases and enhance food safety.

Symbiotic Antimicrobial Effects of Cellulose-Based Bio-Nanocomposite for Disease Management of Agricultural Crops

In the present work, a bionanocomposite for plant crop protection was prepared by non-toxic biocompatible & biodegradable nanomaterials (Cellulose & TiO2 ) to utilize its synergistic effects against antimicrobial pathogens. The commercially available microcrystalline cellulose has been reduced to a nanometric scale regime using acid hydrolysis, while the standard TiO2 nano-powder of particle size ~20 nm has been used to prepare their nanocomposite (NC). The antibacterial studies via agar well diffusion method demonstrated that after 72 h of incubation, parent nanomaterials Ncell and TiO2 were not showing any activity against phytopathogens X. campestris pv. campestris, and Clavibacter while the nanocomposite's NC's were still effective depicting both bacteriostatic and bactericidal actions. However, the bacterial growth of biocontrol P. fluorescence was not affected by Ncell, TiO2 NPs and NC after 72 h of incubation. The antifungal testing results via poison food agar assay method suggest that the nanocomposite, along with Ncell and TiO2 NPs, exhibited strong inhibition of fungal growth of Phytophthora Spp at 0.125 mg/ml concentration while for F. graminearum, similar effect was observed at 0.25 mg/ml concentration. The nanocomposite has proved its potential by exhibiting longer & stronger synergistic effects against plant pathogens as a good antimicrobial agent for protection of agricultural crops.

Chlorhexidine-Silver Nanoparticle Conjugation Leading to Antimicrobial Synergism but Enhanced Cytotoxicity

This study explored the potential synergism within chlorhexidine-silver nanoparticle conjugates against Influenza type A, Staphylococcus aureus, Escherichia coli, and Candida albicans. Silver nanoparticles (SN) were obtained by the reduction of silver ions with green tea total phenolic extract and conjugated with chlorhexidine (Cx). The particles were characterized by UV-Vis and FTIR spectroscopies, dynamic light scattering, X-ray diffraction, and transmission electron microscopy. A stable negatively charged nano-silver colloid (ζ = -50.01) was obtained with an average hydrodynamic diameter of 92.34 nm. In the presence of chlorhexidine, the spectral data and the shift of the zeta potential to positive values (ζ = +44.59) revealed the successful sorption of the drug onto the silver surface. The conjugates (SN-Cx) demonstrated potentiation in their effects against S. aureus and C. albicans and synergism against E. coli with minimal inhibitory concentrations of SN at 5.5 µg/mL + Cx 8.8 µg/mL. The SN showed excellent virucidal properties, increasing with time, and demonstrated low toxicity. However, the coupling of the cationic chlorhexidine with nano-silver did not reduce its intrinsic cytotoxicity on various cell lines (MDCK, BJ, and A549). The newly synthesized antimicrobial agent exhibited an extended and promising therapeutic spectrum and needs to be further evaluated regarding the designated route of administration in three-dimensional cell models (e.g., nasal, bronchial, dermal, ocular, etc.).

The effect of nanobased irrigants on the root canal dentin microhardness: an ex-vivo study

BACKGROUND

Given the favorable antimicrobial properties of zinc oxide (ZnONPs), standard silver (AgNPs), and imidazolium-based silver (Im-AgNPs) nanoparticles, this study aimed to evaluate their influence on the microhardness of root canal dentin.

METHODS

In this experimental study, 40 mandibular premolars were decoronated at the cementoenamel junction and longitudinally sectioned into halves to create 80 specimens. They were randomly allocated to 5 groups (n = 16) and irrigated with ZnONPs, AgNPs, Im-AgNPs, NaOCl, or normal saline (as the negative control) for 15 min. The Vickers Hardness Number (VHN) was measured on each root canal third before and after being soaked in irrigants. Statistical analysis was performed using paired t-test, one-way ANOVA, and post hoc Tukey's test (α = 0.05).

RESULTS

Im-AgNPs and ZnONPs irrigants improved the microhardness of root dentin, whereas, AgNPs and NaOCl decreased it. ZnONPs yielded the highest VHN at the coronal third (P˂0.001), while the Im-AgNPs provided the highest VHN at the middle and apical thirds (P˂0.001). The AgNPs group showed the lowest VHN at the apical third.

CONCLUSIONS

The irrigants containing Im-AgNPs and ZnONPs significantly enhanced the root dentin microhardness. However, the use of AgNPs resulted in decreased microhardness.

Silver Nanoparticles and Their Therapeutic Applications in Endodontics: A Narrative Review

The efficient elimination of microorganisms and their byproducts from infected root canals is compromised by the limitations in conventional root canal disinfection strategies and antimicrobials. Silver nanoparticles (AgNPs) are advantageous for root canal disinfection, mainly due to their wide-spectrum anti-microbial activity. Compared to other commonly used nanoparticulate antibacterials, AgNPs have acceptable antibacterial properties and relatively low cytotoxicity. Owing to their nano-scale, AgNPs penetrate deeper into the complexities of the root canal systems and dentinal tubules, as well as enhancing the antibacterial properties of endodontic irrigants and sealers. AgNPs gradually increase the dentin hardness in endodontically treated teeth and promote antibacterial properties when used as a carrier for intracanal medication. The unique properties of AgNPs make them an ideal additive for different endodontic biomaterials. However, the possible side effects of AgNPs, such as cytotoxicity and tooth discoloration potential, merits further research.

Silver Nanoparticles Phytofabricated through Azadirachta indica: Anticancer, Apoptotic, and Wound-Healing Properties

Silver nanoparticles (AgNPs) have unlocked numerous novel disciplines in nanobiotechnological protocols due to their larger surface area-to-volume ratios, which are attributed to the marked reactivity of nanosilver, and due to their extremely small size, which enables AgNPs to enter cells, interact with organelles, and yield distinct biological effects. AgNPs are capable of bypassing immune cells, staying in the system for longer periods and with a higher distribution, reaching target tissues at higher concentrations, avoiding diffusion to adjacent tissues, releasing therapeutic agents or drugs for specific stimuli to achieve a longer duration at a specific rate, and yielding desired effects. The phytofabrication of AgNPs is a cost-effective, one-step, environmentally friendly, and easy method that harnesses sustainable resources and naturally available components of plant extracts (PEs). In addition, it processes various catalytic activities for the degradation of various organic pollutants. For the phytofabrication of AgNPs, plant products can be used in a multifunctional manner as a reducing agent, a stabilizing agent, and a functionalizing agent. In addition, they can be used to curtail the requirements for any additional stabilizing agents and to help the reaction stages subside. Azadirachta indica, a very common and prominent medicinal plant grown throughout the Indian subcontinent, possesses free radical scavenging and other pharmaceutical properties via the regulation of proinflammatory enzymes, such as COX and TOX. It also demonstrates anticancer activities through cell-signaling pathways, modulating tumor-suppressing genes such as p53 and pTEN, transcriptional factors, angiogenesis, and apoptosis via bcl2 and bax. In addition, it possesses antibacterial activities. Phytofabricated AgNPs have been applied in the areas of drug delivery, bioimaging, biosensing, cancer treatment, cosmetics, and cell biology. Such pharmaceutical and biological activities of phytofabricated AgNPs are attributed to more than 300 phytochemicals found in Azadirachta indica, and are especially abundant in flavonoids, polyphenols, diterpenoids, triterpenoids, limonoids, tannins, coumarin, nimbolide, azadirachtin, azadirone, azadiradione, and gedunin. Parts of Azadirachta indica, including the leaves in various forms, have been used for wound healing or as a repellent. This study was aimed at examining previously biosynthesized (from Azadirachta indica) AgNPs for anticancer, wound-healing, and antimicrobial actions (through MTT reduction assay, scratch assay, and microbroth dilution methods, respectively). Additionally, apoptosis in cancer cells and the antibiofilm capabilities of AgNPs were examined through caspase-3 expression, dentine block, and crystal violet methods. We found that biogenic silver nanoparticles are capable of inducing cytotoxicity in HCT-116 colon carcinoma cells (IC50 of 744.23 µg/mL, R2: 0.94), but are ineffective against MCF-7 breast cancer cells (IC50 >> 1000 µg/mL, R2: 0.86). AgNPs (IC50 value) induced a significant increase in caspase-3 expression (a 1.5-fold increase) in HCT-116, as compared with control cells. FITC-MFI was 1936 in HCT-116-treated cells, as compared to being 4551 in cisplatin and 1297 in untreated cells. AgNPs (6.26 µg/mL and 62.5 µg/mL) induced the cellular migration (40.2% and 33.23%, respectively) of V79 Chinese hamster lung fibroblasts; however, the improvement in wound healing was not significant as it was for the controls. AgNPs (MIC of 10 µg/mL) were very effective against MDR Enterococcus faecalis in the planktonic mode as well as in the biofilm mode. AgNPs (10 µg/mL and 320 µg/mL) reduced the E. faecalis biofilm by >50% and >80%, respectively. Natural products, such as Syzygium aromaticum (clove) oil (MIC of 312.5 µg/mL) and eugenol (MIC of 625 µg/mL), showed significant antimicrobial effects against A. indica. Our findings indicate that A. indica-functionalized AgNPs are effective against cancer cells and can induce apoptosis in HCT-116 colon carcinoma cells; however, the anticancer properties of AgNPs can also be upgraded through active targeting (functionalized with enzymes, antibiotics, photosensitizers, or antibodies) in immunotherapy, photothermal therapy, and photodynamic therapy. Our findings also suggest that functionalized AgNPs could be pivotal in the development of a novel, non-cytotoxic, biocompatible therapeutic agent for infected chronic wounds, ulcers, and skin lesions involving MDR pathogens via their incorporation into scaffolds, composites, patches, microgels, or formulations for microneedles, dressings, bandages, gels, or other drug-delivery systems.

TA-AgNPs/Alginate Hydrogel and Its Potential Application as a Promising Antibiofilm Material against Polymicrobial Wound Biofilms Using a Unique Biofilm Flow Model

The presence of biofilm within a chronic wound may delay the healing process. Thus, control of biofilm formation and providing bactericidal effect are crucial factors for wound healing management. Alginate-based nanocomposite hydrogels have been suggested as dressing materials for wound treatment, which are employed as a biocompatible matrix. Therefore, in this study, we aimed to develop a biocompatible antimicrobial wound dressing containing AgNPs and demonstrate its efficacy against polymicrobial wound biofilms by using a biofilm flow device to simulate a chronic infected, exuding wound and specific wound environment. The results from agar well diffusion, the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) assays showed that TA-AgNPs exhibited antibacterial activity against wound pathogens. Additionally, the Minimum Biofilm Eradication Concentration assay (MBEC) demonstrated it could impair biofilm formation. Importantly, our TA-AgNPs/Alginate hydrogel clearly showed antibacterial activities against Streptococcus pyogenes, Staphylococcus aureus and Pseudomonas aeruginosa. Furthermore, we used the biofilm flow device to test the topical antimicrobial hydrogel against a three-species biofilm. We found that TA-AgNPs/Alginate hydrogel significantly showed a 3-4 log reduction in bacterial numbers when applied with multiple doses at 24 h intervals, and was especially effective against the chronic wound pathogen P. aeruginosa. This work highlighted that the TA-AgNPs/Alginate hydrogel is a promising material for treating complex wound biofilms.

Comparative evaluation of the antifungal efficacy of sodium hypochlorite, chlorhexidine, and silver nanoparticles against Candida albicans

Candida albicans is a microorganism that causes root canal infections. However, it cannot be eliminated with conventional irrigation solutions. Recently, silver nanoparticles (AgNPs) have become popular for their superior antimicrobial effects. The purpose of this study was to evaluate the antifungal effect of AgNPs to C. albicans comparing with 5.25% sodium hypochlorite (NaOCl) and 2% chlorhexidine (CHX). Silver nanoparticles were synthesized by chemical reduction method. Minimum inhibitory concentration and minimum fungicidal concentration of AgNPs against C. albicans strain were determined according to microdilution method reported by Clinical Laboratory Standards Institute. C. albicans biofilm layer was formed on the dentin blocks for 10 days. The biofilm structure was observed by scanning electron microscopy. Statistical analysis was performed with one way analysis of variance analysis and group comparisons were performed with Tukey test. AgNPs showed the highest antifungal effect among the groups. 5.25% NaOCl showed the lowest antifungal effect among the groups. While the 2% CHX solution had a statistically lower antifungal effect than AgNPs, it was found to have a higher effect than NaOCl (p < .016). Nanoparticles present a wide research field as an alternative irrigation solution in root canal treatment. The antifungal effect of AgNPs against C. albicans was confirmed in this study. Further in vivo studies should evaluate the conditions of use and long-term prognosis of AgNPs.

Synthesis and Biological Characterization of Phyto-Fabricated Silver Nanoparticles from Azadirachta indica

Nanoparticles (NPs) have garnered a lot of interest in sectors like medicine, cosmetics, food, and pharmaceuticals for antibacterial catalytic properties, reduced toxicity, and easy production. Biological synthesis of silver nanoparticle (AgNPs) is considered as green, eco-friendly, and cost-effective approach; therefore, Azadirachta indica extracts were utilized for a dual role of fabrication and functionalization of AgNPs. Optical and physical characterizations were achieved for confirming the biosynthesized AgNPs. SEM images detected quasi-spherical AgNPs of 44.04 to 66.50 nm. Some of potent phytochemicals like flavonoids and proteins from Azadirachta indica formed a strong coating or capping on the AgNPs without affecting their secondary structure by interacting with Ag+ and NPs for the formation of AgNPs. AgNPs exhibited strong antibacterial activity (MIC 10 μg/ml) against multidrug-resistant bacteria Enterococcus faecalis; at different concentrations, no IC50 values were recorded for AgNPs as well as Azadirachta indica signifying low cytotoxicity in the exposed concentration range. The DNA degradation activity of AgNPs through the TUNEL assay revealed no significant increase in the overall FITC mean fluorescence intensity as well as a DNA fragmentation index with 5.45% DNA damage (10 μg/ml AgNPs). Drug uptake of AgNPs was also investigated through a permeability assay via Caco-2 cell lines at test concentrations where apparent permeability was detected as moderate.

Silver-doped active carbon spheres and their application for microbial decontamination of water

Highly efficient and durable, silver nanoparticles doped Active Carbon Spheres ACS(Ag) were synthesized by carbonization and activation of silver exchanged resins. The silver exchanged resins were prepared by exchanging H⁺ ions of polystyrene sulphonate resin with Ag⁺ ions of silver nitrate (AgNO₃). The quantity of Ag⁺ in the spheres was controlled by varying the concentration of AgNO₃, from 0.0125 to 0.1 M. With increasing molar concentration of AgNO_3, the effective intake of Ag⁺ by the sphere increases from 1.1 to 8.1 weight percent (wt %). For activation, the spheres were incubated in the CO₂ atmosphere for 6 h at fixed soaking temperature i.e. 1123 K. The characterization of synthesized silver doped ACS was performed by using different sophisticated instrumental techniques. The antimicrobial activity of silver doped ACS was studied against different bacterial strains like, E. coli, B. subtilis and Staphylococcus aureus. The study demonstrated that the zone of inhibition for E. coli was 16.9 ± 0.7 mm while for B. subtilis it was 17.1 ± 0.3 mm at a concentration of 8 mg of synthesized material. In addition, satisfactory results were obtained in shake flask and filtration test experiments also, even at a low concentration of 2 mg, showing growth inhibition of 94% for E. coli and 93% for B. subtilis. When the concentration of silver doped ACS was increased to 8 mg, complete removal of both the bacteria was observed after 24 h (100 % reduction for E. coli and B. subtilis). Furthermore, when silver doped ACS was tested against Staphylococcus aureus according to ASTM:E 2149-01 method, biocidal activity of up to 73% was observed. Therefore, the silver doped ACS can be considered as a potential biocidal material for the studied bacterial strains and hence find suitable application for decontamination of water.

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Novel low-density silver doped active carbon spheres (ACS) were synthesized successfully.

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Characterization and antibacterial activity was examined for water decontamination application.

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Results revealed that the material effectively reduced microbial load by 99.9 %.

Present status and future directions of intracanal medicaments

Two fundamental goals of endodontic treatment are to prevent or treat apical periodontitis. From a predictive perspective, several variables can affect the outcome of root canal treatment. Some of these variables depend on intraoperative factors, which include irrigation technique, size of the apical preparation, use of intracanal medicaments or the number of appointments necessary to complete the treatment. However, the outcome may also be affected by host and microbial factors. The intensity of periradicular bone loss or tissue damage, the presence of preoperative pain and associated conditions such as mechanical allodynia and central sensitization, the anatomical complexity of the apical portion of the canal, and the virulence and longevity of the bacterial infection can all have a profound influence on the outcome. Furthermore, numerous medical conditions have been reported to decrease the capability of the immune system to heal the periapical tissues. It is the clinician's responsibility to analyse these variables and incorporate them into the disinfection strategy to maximize the chances of healing. This narrative review will focus on the present status of intracanal medicaments, the clinical indications for their use and future directions for research.

Myrobalan-Mediated Nanocolloids in Controlling Marine Pathogens

Aquaculture production is affected by disease outbreak, which affects the production, profitability, and sustainability of the global aquaculture industry. Antibiotics have been widely used to control various infectious diseases. Indiscriminate usage of antibiotics results in development of antibiotic resistance in pathogens. This current study aims to synthesize myrobalan-mediated green silver nanocolloids (MBNc) by using the extract of three myrobalans and characterized by using various physiochemical techniques. Antibacterial potential of MBNc was screened in vibriosis causing pathogens (V. harveyi, V. alginolyticus, V. Parahaemolyticus), and foodborne pathogen S. haemolyticus, isolated from infected fish. Further, the presence of ESBL genes including CTX-M-15 and Amp C was analyzed in control and MBNc-treated strains. From our studies, it was observed that MBNc was very effective in controlling the growth. MBNc confirmed the anti-biofilm property in all tested marine pathogens and effectively abolish the genes encoding CTX-M-15 in tested pathogens. Thus, MBNc can be formulated to control the growth of marine pathogens and it can be used as an alternative to antibiotics to prevent infection in cage culturing and aquafarming.

Antimicrobial Efficacy of Glass Ionomer Cement in Incorporation with Biogenic Zingiber officinale Capped Silver-Nanobiotic, Chlorhexidine Diacetate and Lyophilized Miswak

In the present study, Zingiber officinale is used for the synthesis of Zingiber officinale capped silver nanoparticles (ZOE-AgNPs) and compares the antimicrobial efficacy and compressive strength of conventional glass ionomer cement (GIC) combined with ZOE-AgNPs, lyophilized miswak, and chlorhexidine diacetate (CHX) against oral microbes. Five groups of the disc-shaped GIC specimens were prepared. Group A: lyophilized miswak and GIC combination, Group B: ZOE-AgNPs and GIC combinations, Group C: CHX and GIC combination, Group D: ZOE-AgNPs + CHX + GIC; Group E: Conventional GIC. Results confirmed the successful formation of ZOE-AgNPs that was monitored by UV-Vis sharp absorption spectra at 415 nm. The X-ray diffractometer (XRD) and transmission electron microscope (TEM) results revealed the formation of ZOE-AgNPs with a mean size 10.5-14.12 nm. The peaks of the Fourier transform infrared spectroscopy (FTIR) were appearing the involvement of ZOE components onto the surface of ZOE-AgNPs which played as bioreducing, and stabilizing agents. At a 24-h, one-week and three-week intervals, Group D showed the significantly highest mean inhibitory zones compared to Group A, Group B, and Group C. At microbe-level comparison, Streptococcus mutans and Staphylococcus aureus were inhibited significantly by all the specimens tested except group E when compared to Candida albicans. Group D specimens showed slightly higher (45.8 ± 5.4) mean compressive strength in comparison with other groups. The combination of GIC with ZOE-AgNPs and chlorhexidine together enhanced its antimicrobial efficacy and compressive strength compared to GIC with ZOE-AgNPs or lyophilized miswak or chlorhexidine combination alone. The present study revealed that The combination of GIC with active components of ZOE-AgNPs and chlorhexidine paves the way to lead its effective nano-dental materials applications.

How Adding Chlorhexidine or Metallic Nanoparticles Affects the Antimicrobial Performance of Calcium Hydroxide Paste as an Intracanal Medication: An In Vitro Study

The aim of our study was to explore the potential value of metallic (Ag, Cu, and Zn) salts, polymer/metallic nanoparticles, and chlorhexidine (CHX) for improving the antimicrobial activity of calcium hydroxide (CH) against E. faecalis and C. albicans, associated with persistent endodontic infections. A first screening was performed by determining minimum inhibitory/bactericidal concentrations (MIC/MBC). Antimicrobial activity of the CH paste mixed with metallic salts, chitosan or cyclodextrin polymer metallic nanoparticles was compared to the antimicrobial activity of CH paste alone and CH + CHX using a time-kill kinetics assay. The effect of the antimicrobials on the rheological and the key mechanical properties were also examined. Copper and zinc were discarded because of their MIC/MBC values and silver because of its kill time curve profile. Except for a slower setting time after 24 h and a higher weight loss after 1 week of incubation, the mechanical behavior of the CH paste was unaffected by the addition of CHX. Polymeric/metallic nanoparticles failed to potentiate the antimicrobial effect of CH. By contrast, CHX increased this effect and thus could help eradicate E. faecalis associated with persistent root canal infections without altering the desired key physical properties of the CH paste.

Silver nanoparticles in endodontics: recent developments and applications

The elimination of endodontic biofilms and the maintenance of a leak-proof canal filling are key aspects of successful root canal treatment. Several materials have been introduced to treat endodontic disease, although treatment success is limited by the features of the biomaterials used. Silver nanoparticles (AgNPs) have been increasingly considered in dental applications, especially endodontics, due to their high antimicrobial activity. For the present study, an electronic search was conducted using MEDLINE (PubMed), the Cochrane Central Register of Controlled Trials (CENTRAL), Google Scholar, and EMBASE. This review provides insights into the unique characteristics of AgNPs, including their chemical, physical, and antimicrobial properties; limitations; and potential uses. Various studies involving different application methods of AgNPs were carefully examined. Based on previous clinical studies, the synthesis, means of obtaining, usage conditions, and potential cytotoxicity of AgNPs were evaluated. The findings indicate that AgNPs are effective antimicrobial agents for the elimination of endodontic biofilms.

Antibacterial effect of silver nanoparticles mixed with calcium hydroxide or chlorhexidine on multispecies biofilms

The purpose is to evaluate the antibacterial effects of the silver nanoparticles (AgNPs) (Nanografi, METU Teknokent, Ankara, Turkey) mixed with calcium hydroxide (Ca(OH)₂) (Ultracal XS, Ultradent, St Louis, US) or chlorhexidine gel (CHX) (Gluco-Chex, Cerkamed, Stalowa Wola, Poland) against a multispecies biofilm, by confocal laser scanning microscopy (CLSM) and culture-based analysis. Dentine blocks were inoculated with Enterococcus faecalis, Streptococcus mutans, Lactobacillus acidophilus and Actinomyces naeslundii for 1 week. Infected dentine blocks were randomly divided into groups according to medication; saline solution (SS), Ca(OH)₂, Ca(OH)₂ + AgNP, 2%CHX gel and 2%CHX gel + AgNP and time of application: 1 and 7 days (all groups, n = 5). Bacterial samples were collected before and after medication to quantify the bacterial load. Biofilm elimination was quantitatively analyzed by Live/Dead BacLight Bacterial Viability staining and CLSM. The addition of AgNPs to Ca(OH)₂ increased the effectiveness of medicament in terms of bacterial reduction in both application times (1 and 7 days) (p < 0.05: ANOVA, Tukey's test) according to culture-based analysis. The CLSM images revealed that mixture of AgNP with CHX killed significantly more bacteria when compared with all other medicaments at 1- and 7-day application times (p < 0.05 and p > 0.05, respectively: Kruskal-Wallis, Dunn post hoc tests). The efficacy of Ca(OH)₂ mixed with AgNPs was superior to Ca(OH)₂ used alone in both application times (p < 0.05) according to CLSM analysis. The present study put forth the potential use of AgNPs mixed with Ca(OH)₂ or CHX on multispecies (Enterococcus faecalis, Streptococcus mutans, Lactobacillus acidophilus and Actinomyces naeslundii) biofilm in 1 and 7day application periods.

Antibacterial Effects of Erbium Chromium Laser along with/without Silver Nanoparticles in Root Canals Infected by Enterococcus faecalis

This study investigates the antibacterial effects of erbium chromium laser at 2780 nm, silver nanoparticles, and erbium chromium along with silver nanoparticles on Enterococcus faecalis in comparison with sodium hypochlorite. In the present study, 90 extracted human single-rooted teeth were selected and standardized to a length of 15 mm. The canals were prepared by V-taper Gold rotary files and then incubated with E. faecalis for 21 days. The samples were divided into four experimental groups including hypochlorite sodium, silver nanoparticle, erbium chromium laser, and erbium chromium laser along with silver nanoparticle groups. Results showed that there was a significant reduction in colony count for all groups after interventions. Moreover, there was a significant reduction in the colony count for sodium hypochlorite group in comparison with another groups, and this group showed the highest reduction of colony count. There was a significant difference between silver nanoparticles and erbium chromium laser groups in colony count. According to the results, the silver nanoparticles offered strong antibacterial effects on E. faecalis and therefore can decrease bacterial colonies, while the use of the laser, despite the reduction of the bacterial colony, could not be sufficiently used for disinfection of root canal system.

Applications of Silver Nanoparticles in Dentistry: Advances and Technological Innovation

Silver nanoparticles (AgNPs) have been successfully applied in several areas due to their significant antimicrobial activity against several microorganisms. In dentistry, AgNP can be applied in disinfection, prophylaxis, and prevention of infections in the oral cavity. In this work, the use of silver nanoparticles in dentistry and associated technological innovations was analyzed. The scientific literature was searched using PubMed and Scopus databases with descriptors related to the use of silver nanoparticles in dentistry, resulting in 90 open-access articles. The search for patents was restricted to the A61K code (International Patent Classification), using the same descriptors, resulting in 206 patents. The results found were ordered by dental specialties and demonstrated the incorporation of AgNPs in different areas of dentistry. In this context, the search for patents reaffirmed the growth of this technology and the dominance of the USA pharmaceutical industry over AgNPs product development. It could be concluded that nanotechnology is a promising area in dentistry with several applications.

Pivotal Local Drug Delivery Systems in Endodontics; A Review of Literature

Endodontic pathosis is preliminary caused by bacteria and their by-products that interact with pulpal and periradicular host tissues. The purge of the root canal system (RCS) from bacteria is a necessity for successful endodontic treatment. Different approaches have been considered to reduce the number of microorganisms and confront microbiota in the radicular area; namely chemomechanical preparation and intracanal medication. However, various studies have shown that, due to the intricate anatomy of RCS, bacteria can persist in distant areas and significantly decrease the degree of success in endodontic ministrations. Thereby, elimination of bacteria remains a challenge, specifically from the infectious root canals. In recent years, local drug delivery systems (LDDS), loaded with drugs and/or antibacterial agents, have been deliberated for the removal of microorganisms or as a medicinal adjunct to mechanical instrumentation. Owing to the resistant species and complexities in the structure of root canals, it seems that LDDS may be able to closely affect microorganisms and improve the success rate of endodontic treatment. Furthermore, they are capable of limiting drugs to RCS, and can achieve a more effective therapeutic dose/concentration in the target site. Furthermore, and due to successful outcomes, administration of LDDS has also been given great attention for regenerative purposes. Micro/nanoparticles, liposomes, nanofibers, sealers and so forth represent typical delivery systems used for endodontic treatments. This study addresses pivotal LDDS used in endodontics and their applications.

Application of Antimicrobial Nanoparticles in Dentistry

Oral cavity incessantly encounters a plethora of microorganisms. Plaque biofilm-a major cause of caries, periodontitis and other dental diseases-is a complex community of bacteria or fungi that causes infection by protecting pathogenic microorganisms from external drug agents and escaping the host defense mechanisms. Antimicrobial nanoparticles are promising because of several advantages such as ultra-small sizes, large surface-area-to-mass ratio and special physical and chemical properties. To better summarize explorations of antimicrobial nanoparticles and provide directions for future studies, we present the following critical review. The keywords "nanoparticle," "anti-infective or antibacterial or antimicrobial" and "dentistry" were retrieved from Pubmed, Scopus, Embase and Web of Science databases in the last five years. A total of 172 articles met the requirements were included and discussed in this review. The results show that superior antibacterial properties of nanoparticle biomaterials bring broad prospects in the oral field. This review presents the development, applications and underneath mechanisms of antibacterial nanoparticles in dentistry including restorative dentistry, endodontics, implantology, orthodontics, dental prostheses and periodontal field.