High Antimicrobial Efficacy Research Articles

Effective Antibacterial Activity of Degradable Copper-Doped Phosphate-Based Glass Nanozymes.

Copper-containing antimicrobials are highly valuable in the field of medical disinfectants owing to their well-known high antimicrobial efficacy. Artificially synthesized nanozymes which can increase the level of reactive oxygen species (ROS) in the bacterial system have become research hotspots. Herein, we describe the design and fabrication of degradable Cu-doped phosphate-based glass (Cu-PBG) nanozyme, which can achieve excellent antibacterial effects against Gram-positive and Gram-negative bacteria. The antibacterial mechanism is based on the generation of ROS storm and the release of copper. It behaves like a peroxidase in wounds which are acidic and exerts lethal oxidative stress on bacteria via catalyzing the decomposition of H2O2 into hydroxyl radicals (•OH). Quite different from any other reported nanozymes, the Cu-PBG is intrinsically degradable due to its phosphate glass nature. It gradually degrades and releases copper ions in a physiological environment, which further enhances the inhibition efficiency. Satisfactory antibacterial effects are verified both in vitro and in vivo. Being biodegradable, the prepared Cu-PBG exhibits excellent in vivo biocompatibility and does not cause any adverse effects caused by its long-time residence time in living organisms. Collectively, these results indicate that the Cu-PBG nanozyme could be used as an efficient copper-containing antimicrobial with great potential for clinical translation.

Antimicrobial, Antioxidant and Cytotoxic Activity of Green Synthesized Copper Nanoparticle of Parthenium Hysterophorus L.

Natural products are valuable and well known for their biological activities. In the current scenario, the research and analysis of plant leaf extract and nanoparticles synthesis with their biological activities has been expended significantly. For the synthesis of nanoparticles, Copper is the preferred metal among other metals due to its reported use in medical field as antimicrobial agents and its lethality. The aim of the present work is to assess antimicrobial and antioxidant activities of the methanolic leaf extracts and aqueous leaf extract mediated copper nanoparticles of Parthenium hysterophorus. Study also revealed the comparative analysis between methanolic leaf extracts and copper nanoparticles. Synthesis of copper nanoparticles (CuNPs) was confirmed by the change of color of aqueous extract, which were further confirmed by using UV-Vis spectrophotometer. The results indicated that copper nanoparticles have great antimicrobial activity against Bacillus subtilis, Staphylococcus aureus, Candida albicans and Aspergillus flavus rather than methanolic leaf extract. These studies confirmed that copper nanoparticles are capable to rendering high antimicrobial efficacy and hence has a great potential in the development of antimicrobial agents. Based on the DPPH, copper nanoparticles found to be good antioxidant when compared to methanolic leaf extract. Furthermore cells viability assay was also done against copper nanoparticles. These results concluded that copper nanoparticles are good source of therapeutic agent and applications of copper nanoparticles based on these findings may lead to valuable discoveries in various fields such as medical devices and antimicrobial systems.

Comparative Evaluation of Antimicrobial Efficacy of Calcium Hydroxide, Triple Antibiotic Paste, and 2% Chlorhexidine Combined with 0.5% Cetrimide against Enterococcus faecalis Biofilm-Infected Dentin Model: An In vitro Study.

Background:Enterococcus faecalis is the most common and important microorganism found in infected root canals associated with persistent periapical periodontitis and failing endodontically treated tooth. Intracanal medicaments used after chemomechanical preparation of an infected root canal play a vital in eradication of this microorganism and pave the way for long-term success of endodontic therapy. Hence, the present in vitro study was conducted to assess the antimicrobial efficacy of calcium hydroxide (Ca(OH)2), triple antibiotic paste (metronidazole 400 mg + minocycline 100 mg + ciprofloxacin 500 mg), and 2% chlorhexidine (CHX) combined with 0.5% cetrimide on eradication of E. faecalis biofilm.Materials and Methods:Eighty dentin specimens were taken and infected extraorally with E. faecalis to induce microbial colonization. The specimens were then divided into four groups of twenty each based on medicaments used and further subdivided into two subgroups based on assessment of live cells done either immediately after the elimination of the medicament or after 24-h incubation in brain–heart infusion (BHI) medium: Group I specimens were treated with Ca(OH)2, Group II with triple antibiotic paste, Group III with 2% CHX combined with 0.5% cetrimide, and Group IV with saline (control) for 7 days at 37°C. Assessment of live cells was done using confocal microscope.Results:2% CHX combined with 0.5% cetrimide (Group III) and triple antibiotic paste (Group II) showed a statistically significant result with high antimicrobial efficacy and lower percentage of live cells as compared to Ca(OH)2 (Group I). The mean percentage of live cells in Group I immediately after elimination of medicaments was 64.7%, in Group II was 1.52%, in Group III was 1.49%, and in Group IV was 83.4%. After 24 h of incubation in BHI medium, 2% CHX combined with 0.5% cetrimide (Group III) showed a statistically significant (p < 0.05) result of 1.27% mean live cells as compared to 84.2% in Ca(OH)2 (Group I), 1.82% in triple antibiotic paste (Group II), and 94.2% in saline (Group IV control).Conclusion:2% CHX combined with 0.5% cetrimide exhibited maximum antimicrobial efficacy with least number of mean live cells followed by triple antibiotic paste as compared to Ca(OH)2. Based on these findings, 2% CHX combined with 0.5% cetrimide was most effective in eradicating E. faecalis from the extraorally infected dentine biofilm.

Antimicrobial Efficacy of Plant Extracts Combined with Endodontic Sealer on the Growth of Oral Pathogen - An In Vitro Study

Aim: The aim of this study is to evaluate the antimicrobial efficacy of synthetic sealing material (Zinc oxide eugenol based sealer- Pulp canal sealer EWT) and medicinal plant extracts (Glycyrrhiza glabra, Zingiber officinale, Cinnamon zeylanicum) individually and in combination against oral pathogen (Enterococcus faecalis). Methods: The herbal extracts were independently mixed in different ratios with zinc oxide powder, followed by mixing with eugenol to know the effective concentration using antibacterial assay. Different concentrations of each test material were placed into Agar diffusion wells and zones of inhibition were measured against the selected bacteria. The concentration with maximum zone of inhibition for each test material was assessed and grouped as group I- Glycyrrhiza glabra and pulp canal sealer EWT, group II-Zingiber officinale and pulp canal sealer EWT, group III-Cinnamon zeylanicum and pulp canal sealer EWT,Group IV- Plain pulp canal sealer EWT and compared. Results: It was found that all the groups exhibited varied antimicrobial activity against test microorganism. Highest antimicrobial efficacy was noticed in group III followed by group II, group I and least with group IV samples. Conclusion: Zinc oxide eugenol based sealer with plant extracts produced inhibitory zones against tested microorganism. Hence the plant extract can be added as one of the component of endodontic sealer, but further clinical trials need to be conducted before recommending them as sealers.

Dehydroepiandrosterone derived imidazolium salts and their antimicrobial efficacy

Hybrid molecules consisting of steroid-imidazolium salts reveal interesting biological properties, especially regarding antimicrobial activities. Novel dehydroepiandrosterone derived imidazolium salts (11 salts) with side chains of different lengths were obtained in an efficient and straightforward synthetic route. Antimicrobial properties of new salts were examined by determining their minimum inhibitory concentrations (MICs). They were studied against several strains of bacteria, including clinical isolates of MRSA, and fungi. New compounds showed high activity against Gram-positive bacteria and Candida albicans as well as good compatibility with the representatives of the host cells when applied at concentrations corresponding to MIC value. The studies indicated high antimicrobial efficacy of imidazolium salts against the above-mentioned microorganisms with low hemolytic activity at a concentration that restricts the growth of the microorganisms. The interference of salts with the immune defense system, the influence on the biological activity of monocytes/macrophages measured by their viability and metabolic activity was also studied. The new compounds have shown immunoprotective properties.

Photodynamic antimicrobial chemotherapy through photosensitizers loaded poly-l-glycolic acid on Candida albicans in denture lining material: Release, biological and hardness study.

The aim of this in-vitro study was to formulate poly-l-glycolic acid nanoparticles loaded with methylene blue (PLGA-MB) and to characterize their physicochemical features, photosensitizer-release kinetics and antimicrobial efficacy against Candida albicans (C. albicans) after incorporating in polymethyl methacrylate (PMMA) denture lining materials. MB-PLGA nanoparticles were synthesized according to the modified nanoprecipitation method. The morphological characterization of the nanoparticles was studied under scanning and transmission electron microscope. Particle size, surface charge, polydispersity index (PDI) and MB release were evaluated. The effect of 660 nm semiconductor AlGaInP diode laser on C. albicans was studied in vitro. The PMMA was weighed and PLGA free and PLGA-MB were added in the lining material according to the weight percentage as 2.0 wt.% and 5.0 wt.% and tested for the diameter of the inhibition zones of C. albicans growth and shore A hardness. Homogenous spherical nanoparticles with round morphology with size ranging between 60-80 nm were observed while PLGA-MB were seen to have irregular structure within the nanoparticle under TEM. PLGA-Free was larger in size than the loaded PLGA (∼62 nm) that evidenced reduction in size by adding the MB photosensitizer. PDI recordings reduced from 0.198 for the PLGA-Free nanoparticles to 0.164 for the PLGA-MB nanoparticles. The entrapment efficiency of MB inside PLGA showed an average percentage of ∼75 % uptake that resulted in the overall loading of ∼15 %. An overall inhibition of 78 %, 41 % and 28 % of C. albicans growth was seen with a concentration of 0.1, 0.5 and 1.0 μg/mL, respectively. The application of PLGA nanoparticles loaded with MB evidenced >75 % of C. albicans. MB incorporation did not lead to a clinically relevant change on shore A hardness. PLGA loaded with MB is believed to have promising target therapy against C. albicans in denture soft lining materials in terms of PACT in vitro. The synergistic association between PLGA and MB proved enhanced antifungal activity. PLGA-MB could be an important tool in nanobiotechnology and photodynamic therapy for novel formulations with higher antimicrobial efficacy and improved drug delivery from denture soft lining materials.

Retaining the ‘essence’ of essential oil: Nanoemulsions of citral and carvone reduced oil loss and enhanced antibacterial efficacy via bacterial membrane perturbation

Essential oils (EO), which can be extracted from different edible, therapeutic and herbal plants, have been well known as natural antimicrobial additives. However, it is usually hard to attain high antimicrobial efficacy of these EOs, when these are used in different combinations for the control of foodborne microbes, because of their low solubility in water and interactive binding. Here, we report an optimized oil-in-water (o/w) nanoemulsification process for citral and carvone which generated mean droplet size of 11–19 nm. It was found that nature of surfactant viz., Brij-58 vs leaf extract of Lantana camara (LC) plays crucial role in determining the overall stability and size of the droplets. The screened nanoemulsions (NEs), when stored for long duration, showed minimal decrease in oil content with retention of antioxidant activity. The prepared NEs documented enhanced antibacterial activity compared to pure oils whereas higher degree of killing was observed towards Pseudomonas aeruginosa. The NEs also showed killing of both the bacteria on wound dressing cotton gauze bandages (GB). The outcome of the present study may be used for the development of safe and biocompatible antibacterial agents.

Rugby-ball like Ag modified zirconium porphyrin metal–organic frameworks nanohybrid for antimicrobial activity: Synergistic effect for significantly enhancing photoactivation capacity

Despite of the current advancement in antibacterial material, the bacterial issues are still great challenges in health problems worldwide. Herein, Ag nanoparticles doped to zirconium porphyrin metal–organic frameworks (ZPM@Ag) were synthesized for antibacterial activity. The effect of different dosage of Ag nanoparticles on the antibacterial activity was also investigated. The morphology, porous microstructure, and composition of the prepared nanohybrids were characterized by SEM, TEM, XRD, FT-IR, XPS and BET analysis. The results revealed that the optimized antimicrobial efficiency was ZPM@Ag(2). The reactive oxygen species (ROS) production of ZPM@Ag(2) under visible light was obviously abundant than that in the dark, and moreover, the nanohybrid exhibited high antimicrobial efficacy. Furthermore, the antimicrobial mechanism of the prepared sample was also carefully investigated. The enhanced photoactivation antimicrobial activity could be ascribed to the synergistic effect between zirconium porphyrin MOFs (ZPM) and Ag nanoparticles, which possesses high specific surface area and abundant active sites due to the uniform rugby-ball like shape. ZPM@Ag(2) nanohybrid was demonstrated excellent stability even after five cycles. The antimicrobial Ag nanoparticles immobilized in photocatalytic antibacterial porous MOFs are expected to provide a guideline to broaden the applications of MOFs and design novel metal-based antibacterial nanomaterials.

Evaluation of antimicrobial efficacy of three calcium silicate-based materials using tube dilution: An in vitro study

Periapical pathosis is considered as a persistent microbial infection throughout the treatment period of root canal procedures. Recently the prevalence of endodontic failures is huge and this primarily accounts for the periapical pathogens; mainly Enterococcus faecalis and Candida albicans. Thus, with the advent of newer materials; identification of the most appropriate sealing material with highest antimicrobial efficacy is essential for endodontic success. To evaluate and compare the antimicrobial efficacy of MTA Angelus, Biodentine and Theracal LC against Enterococcus faecalis and Candida albicans. An in-vitro study was conducted using three silicate-based cements; MTA Angelus, Biodentine and Theracal LC. Their antimicrobial efficacy was evaluated using Tube dilution method and their Minimum inhibitory concentration (MIC) and Bacterial counts (CFU’s) were assessed and compared. Statistical analysis was done using Paired t-test and ANOVA at 95% confidence interval (p value &amp;#60;0.05).The MIC was highest and CFU’s were lowest with Biodentine in comparison with other two materials.There were statistically significant differences noted between Biodentine and MTA angelus: Our study results conclude that Biodentine was found to be more anti-bacterial as compared to MTA angelus and theracal LC.

Iodinated xanthene-cyanine NIR dyes as potential photosensitizers for antimicrobial photodynamic therapy

Photosensitizers (PSs) are chemical entities that upon light exposure are able to produce cytotoxic species such as singlet oxygen superoxide and free radicals. PSs are used in photodynamic therapy applications (PDT) to eradicate cancer cells, pathogenic bacteria, fungi, and viruses. Development of the NIR-activatable photosensitizes with high phototoxicity and low toxicity in dark conditions is challenging. Here we first report on the synthesis and antimicrobial testing of the new NIR photosensitizers based on the iodinated xanthene-cyanine dyes. These new photosensitizers exhibit high antimicrobial efficacy on Staphylococcus aureus pathogens at low dye concentration (~0.5 μM) and low NIR light dose (24.3 J/cm2).

Justification of preservative choice and its concentration in the composition of anti-allergic action gel

Microbiological stability of medicines is an integral part of their quality, therefore, at the stage of pharmaceutical development, the issues of ensuring microbiological purity should be considered. To this end, various chemicals are added to the composition of semisolid medicines that actively inhibit the growth of microorganisms that enter the pharmaceutical system during production and reuse. Insufficient amount of a preservative can lead to the adaptation of microorganisms, and excess- to increase the toxicity of the drug. In the development of the composition of the anti-allergic action gel containing dimethindene maleate and dexpanthenol in order to select a preservative and its concentration, the following antimicrobial substances have been chosen: phenoxyethanol, benzalkonium chloride, methylparahydroxybenzoate (nipagin, E218), propylparahydroxybenzoate (nipasol, E216) and potassium sorbate (E202).&#x0D; The purpose of this work is to evaluate the effectiveness of these antimicrobial preservatives in the composition of the gel under study.&#x0D; For microbiological studies 5 samples have been developed: N 1 – gel + phenoxyethanol 0.75%; N 2 – gel + benzalkonium chloride 0.015%; N 3 – gel + nipagin 0.15% + nipasol 0.05%; N 4 – gel + potassium sorbate 0.2%; N 5 – gel without preservatives added. The research used the method for evaluating the effectiveness of antimicrobial preservatives given in SPU 2.0 (Section 5.1.3).&#x0D; As a result of the experiment, it has been determined that the sample of gel without preservative does not meet the requirements of SPU and proved the need to add antimicrobial preservatives to the composition of the developed gel. The results of the study for samples with preservatives phenoxyethanol 0.75%, benzalkonium chloride 0.015%, nipagin 0.15% + nipasol 0.05% completely meet the requirements of SPU on the indicator «antimicrobial effectiveness of preservatives» for medicinal products for external use. An experimental study of the sample with a potassium sorbate 0.2% preservative showed that it did not fully meet the requirements of the above article of SPU. Among the samples that meet the requirements of SPU, the highest antimicrobial efficacy against strains of Staphylococcus aureus ATCC 6538, Pseudomonas aeruginosa ATCC 9027, Candida albicans ATCC 885-653, Aspergillus brasiliensis ATSC 16404 has shown a sample of 0.75% phenoxyethanol preservative (N 1). Therefore, for further microbiological studies, samples of gels with phenoxyethanol concentrations of 0.5%, 0.75% and 1.0% were prepared and the antimicrobial efficacy of these samples has been studied. Based on experimental studies, it has been found that 0.75% is the optimal concentration of phenoxyethanol in the composition of gel containing dimethidene maleate and dexpanthenol.&#x0D; Thus, a complex of studies has been conducted to prove the antimicrobial effectiveness of the phenoxyethanol preservative and its concentration.

Experimental evaluation of cationic-Schiff base surfactants based on 5-chloromethyl salicylaldehyde for improving crude oil recovery and bactericide

In this study, a new family of cationic and cationic–Schiff Base surfactant was synthesized namely; N-(3-formyl-4-hydroxybenzyl)-N, N-dimethylhexadecan-1-aminium chloride (FHDHAC), (E)-N-(3-((butylimino)methyl)-4-hydroxybenzyl)-N,N-dimethylhexadecan-1-aminium chloride (4-IMHDAC), (E)-N-(3-((hexylimino)methyl)-4-hydroxybenzyl)-N,N-dimethylhexadecan-1-aminium chloride (6-IMHDAC) and (E)-N-(4-hydroxy-3-((octylimino) methyl)benzyl)-N,N-dimethylhexadecan-1-aminium chloride (8-IMHDAC) were prepared from 5-chloromethyl salicylaldehyde compound (5-CMS). The chemical structures of 5-CMS, 4-IMHDAC, 6-IMHDAC, and 8-IMHDAC are characterized using FTIR, 1H NMR instruments. The surface activity measurements of the prepared compounds showed a gradual increase in surface activity by increasing the alkyl chain length. Adsorption and micellization thermodynamic functions revealed the higher tendencies of the different surfactants towards adsorption at the organic/polar phase. The synthesized surfactants were evaluated in the enhanced oil recovery process and showed excellent efficiency (63.98%, 71.25%, and 75.72% for 4-IMHDAC, 6-IMHDAC, and 8-IMHDAC, respectively) during the recovery process near their critical micelle concentrations. The prepared surfactants showed high antimicrobial efficacy against different bacteria and fungi.

Antimicrobial Activity and Prevention of Bacterial Biofilm Formation of Silver and Zinc Oxide Nanoparticle-Containing Polyester Surfaces at Various Concentrations for Use.

Food contact surfaces are primary sources of bacterial contamination in food industry processes. With the objective of preventing bacterial adhesion and biofilm formation on surfaces, this study evaluated the antimicrobial activity of silver (Ag-NPs) and zinc oxide (ZnO-NPs) nanoparticle-containing polyester surfaces (concentration range from 400 ppm to 850 ppm) using two kinds of bacteria, Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli), and the prevention of bacterial biofilm formation using the pathogen Listeria monocytogenes. The results of antimicrobial efficacy (reductions ≥ 2 log CFU/cm2) showed that at a concentration of 850 ppm, ZnO-NPs were effective against only E. coli (2.07 log CFU/cm2). However, a concentration of 400 ppm of Ag-NPs was effective against E. coli (4.90 log CFU/cm2) and S. aureus (3.84 log CFU/cm2). Furthermore, a combined concentration of 850 ppm Ag-NPs and 400 ppm ZnO-NPs showed high antimicrobial efficacy against E. coli (5.80 log CFU/cm2) and S. aureus (4.11 log CFU/cm2). The results also showed a high correlation between concentration levels and the bacterial activity of Ag–ZnO-NPs (R2 = 0.97 for S. aureus, and R2 = 0.99 for E. coli). They also showed that unlike individual action, the joint action of Ag-NPs and ZnO-NPs has high antimicrobial efficacy for both types of microorganisms. Moreover, Ag-NPs prevent the biofilm formation of L. monocytogenes in humid conditions of growth at concentrations of 500 ppm. Additional studies under different conditions are needed to test the durability of nanoparticle containing polyester surfaces with antimicrobial properties to optimize their use.

Copper-Containing Glass Ceramic with High Antimicrobial Efficacy

Copper-Containing Glass Ceramic with High Antimicrobial Efficacy

Antimicrobial Efficacy Assessment of Human Derived Composite Amnion-Chorion Membrane

Human derived composite amnion-chorion membrane (ACM) has been used to facilitate wound healing due to reported anti-inflammatory properties and promotion of cell proliferation. This study aimed to assess the antimicrobial properties of the ACM using novel methods to visualize the antimicrobial efficacy of membranes in situ at different time points. Porcine Pericardium Collagen Membranes (PPCM) served as membrane controls. Circular pieces of the membranes were used in three different assays: insert, agar contact and glass-bottom well assays. Streptococcus gordonii were spotted onto the membranes and the plates were subsequently centrifuged to ensure direct bacterial contact with the membranes in the insert and agar contact assays, thus better mimicking bacterial adherence in the oral cavity. After incubation at 37 °C for 8, 24, and 48 hours, the membranes were dyed with the Live/Dead BacLight Bacterial Viability fluorescence stain and analyzed via confocal microscopy. The results demonstrated that the ACM completely inhibited bacterial growth at all time points, whereas the PPCM did not demonstrate any antimicrobial properties. Within the limits of this study, the ACM showed extremely high antimicrobial efficacy against oral streptococci. In addition, our methods may be useful in assessing antimicrobial properties for biomaterials with minimum diffusion ability, when traditional assessment methods are not applicable.

Thermo-responsive triple-function nanotransporter for efficient chemo-photothermal therapy of multidrug-resistant bacterial infection

New strategies with high antimicrobial efficacy against multidrug-resistant bacteria are urgently desired. Herein, we describe a smart triple-functional nanostructure, namely TRIDENT (Thermo-Responsive-Inspired Drug-Delivery Nano-Transporter), for reliable bacterial eradication. The robust antibacterial effectiveness is attributed to the integrated fluorescence monitoring and synergistic chemo-photothermal killing. We notice that temperature rises generated by near-infrared irradiation did not only melt the nanotransporter via a phase change mechanism, but also irreversibly damaged bacterial membranes to facilitate imipenem permeation, thus interfering with cell wall biosynthesis and eventually leading to rapid bacterial death. Both in vitro and in vivo evidence demonstrate that even low doses of imipenem-encapsulated TRIDENT could eradicate clinical methicillin-resistant Staphylococcus aureus, whereas imipenem alone had limited effect. Due to rapid recovery of infected sites and good biosafety we envision a universal antimicrobial platform to fight against multidrug-resistant or extremely drug-resistant bacteria.

Copper-containing glass ceramic with high antimicrobial efficacy

Hospital acquired infections (HAIs) and the emergence of antibiotic resistant strains are major threats to human health. Copper is well known for its high antimicrobial efficacy, including the ability to kill superbugs and the notorious ESKAPE group of pathogens. We sought a material that maintains the antimicrobial efficacy of copper while minimizing the downsides – cost, appearance and metallic properties – that limit application. Here we describe a copper-glass ceramic powder as an additive for antimicrobial surfaces; its mechanism is based on the controlled release of copper (I) ions (Cu1+) from cuprite nanocrystals that form in situ in the water labile phase of the biphasic glass ceramic. Latex paints containing copper-glass ceramic powder exhibit ≥99.9% reduction in S. aureus, P. aeruginosa, K. aerogenes and E. Coli colony counts when evaluated by the US EPA test method for efficacy of copper-alloy surfaces as sanitizer, approaching that of benchmark metallic copper.

Copolymers with both soft and rigid cationic rings as highly selective antimicrobials to combat antibiotic resistant microbes and biofilms.

A new series of main-chain copolymers constructed by linkage of both soft and rigid cationic rings has been developed. The imidazolium-DABCO copolymers possess good biocompatibility, high antimicrobial efficacy and lower propensity to develop resistance against a broad range of microbes, including multidrug resistant strains, and their respective biofilms.

Antimicrobial efficacy of herbal extracts combined with zinc oxide eugenol as an obturating material in primary teeth – An in vitro study

Background and Aims: The aim of this study is to evaluate the antimicrobial efficacy of synthetic obturating material (Zinc oxide eugenol) individually and combined with medicinal plant extracts (Triphala, Aloevera, Tulsi) against four bacterial strains (Streptococcus mutans, Enterococcus faecalis, Staphylococcus aureus, Escherichia coli). Methods: The herbal extracts were independently mixed in different ratios with zinc oxide powder, followed by mixing with eugenol to know the effective concentration using antibacterial assay. Initially different concentrations of each test material were placed into Agar diffusion wells and zones of inhibition were measured against the selected bacteria. The concentration with maximum zone of inhibition for each test material was assessed and grouped as Group I- Triphala and zinc oxide eugenol (80:20), Group II- Aloevera and zinc oxide eugenol (80:20), Group III- Tulsi and zinc oxide eugenol (50:50) and Group IV- Plain zinc oxide eugenol. Results: All the groups exhibited varied antimicrobial activity against test microorganisms which were statistically significant. Highest antimicrobial efficacy was noticed in the group I followed by group II, III and the least with group IV samples. Conclusion: The formulations obtained by incorporating Triphala, Aloevera, Tulsi in Zinc oxide exhibited substantial antimicrobial activity when compared to Zinc oxide eugenol alone. Even though, the tested materials showed good antibacterial activity in this in vitro study, clinical trials need to be conducted before recommending them as obturating materials in primary teeth.

Evaluating the efficacy of three sanitizing agents for extending the shelf life of fresh-cut baby spinach: food safety and quality aspects

The aims of this project were to: 1) compare the antimicrobial efficacy and feasibility of three sanitizers including chlorine dioxide (ClO 2 ), neutral electrolysed water (EW) and peroxyacetic acid (PAA) for the treatment of fresh baby spinach leaves, and 2) to investigate the shelf life and quality attributes of spinach treated with these sanitizers. In the experiment for food safety, spinach leaves were inoculated with Salmonella Typhimurium and then treated by immerging in cold solutions of PAA, ClO 2, EW at different concentrations. Salmonella Typhimurium and total viable count (TVC) were determined immediately before and after the treatment. The treatment with 20 mg/L ClO 2 solution resulted in the highest reductions of S. Typhimurium and TVC (by 1.6 ± 0.1 log CFU/g) compared to other treatments. In the experiment for the shelf life of spinach, the samples were stored at 4 ℃ for 13 days after being treated with 75 mg/L PAA, 60 mg/L free chlorine (FCh) EW and 20 mg/L ClO 2 solutions. The results showed that TVC was significantly influenced by the treatments and storage time. At day 0, TVC of all treated samples was significantly lower than this of the control and the TVC of sample treated with ClO 2 was the lowest. However, by day 10, the TVC was not significantly different among the treated samples and the control. For the sensory qualities and physio-chemical properties of the spinach leaves, the treatment with ClO 2 showed significant reduction in quality of the treated sample since day 7 of the storage while other treatments did not show any significant effect on those parameters during the storage. In summary, although the treatment with 20 mg/L ClO 2 solution resulted in the highest antimicrobial efficacy against S. Typhimurium and TVC of spinach leaves, it also caused negative effects to the quality of spinach during the storage.