Colony Counting Method Research Articles

Hyperbranched polylysine/oxidized carboxymethyl cellolose integrated gelatin composite for wound treatment

Herein, we report the preparation and evaluation of a new composite consisting of gelatin matrix, oxidized carboxymethyl cellulose (OCMC), and hyperbranched polylysine (PL) components for full-thickness wound treatment. To enhance the antimicrobial activity of the gelatin matrix, OCMC/PL was successfully combined with this matrix via the Schiff base reaction. Moreover, allantoin (Alla) as a drug model was loaded by this composite and the optimal formulation for wound healing (PLOCG-Alla) was obtained. The structural properties, thermal stability, crystallinity and interactions between materials were investigated using SEM, TGA, XRD and FTIR techniques. Cytotoxicity and antibacterial capacity were evaluated by MTT assay and colony counting methods, respectively. The release behavior was investigated at two different pH values. Blood coagulation and wound healing potential were also evaluated in vivo. PLOCG-Alla exhibited high antibacterial capacity, pH-dependent release behavior, biocompatibility and high blood clotting ability. It also accelerated wound healing in vivo.

Functional composite films incorporating triphala-derived carbon dots for extending chicken preservation

Triphala-based carbon dots (T-CDs) were successfully prepared using a simple one-step hydrothermal method. T-CDs were characterized by absorbance, fluorescence, Fourier-transform infrared, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy. T-CDs showed bright blue fluorescence at 434 nm upon excitation at 360 nm. Functional composite films were prepared using poly(vinyl alcohol) and gelatin mixture by incorporating T-CDs and applied as a packaging film to extend the shelf life of chicken. The antibacterial activity of T-CDs against Listeria monocytogenes and Staphylococcus aureus was evaluated using well diffusion and colony count methods. T-CDs were evenly dispersed throughout the PVA/Gel solution to form a dense and uninterrupted film. They also formed strong bonds with polymer chains, which improved the tensile strength of the film from 32.44 to 42.70 MPa. Furthermore, the presence of T-CDs significantly enhanced the UV-blocking ability of the PVA/Gel films, achieving 99.7 % for UV-B and 97.2 % for UV-A. In addition, the PVA/Gel/T-CDs composite films showed excellent antioxidant, antimicrobial and UV-barrier properties, extending the shelf life of chicken. Therefore, the PVA/Gel/T-CDs composite films showed great potential as an active food packaging material to extend the shelf life and preserve the visual quality of packaged meat.

Effect of pH on the microstructure and antibacterial properties of MgO nanoparticles by microwave-assisted solution combustion

The application of magnesium oxide (MgO) nanoparticles as a candidate material for antibacterial purposes has been limited by their relatively low antibacterial activity. In this study, antibacterial MgO nanoparticles were synthesised in one step using magnesium nitrate and citric acid as raw materials using an economical and environmentally friendly microwave-assisted solution combustion approach, while the effect of the pH of the reaction system (2, 4, and 7) on the structure and antimicrobial properties of the synthesised MgO nanoparticles was investigated. X-ray diffraction (XRD) analysis demonstrated the formation of cubic-phase MgO nanoparticles, and electron microscopy studies confirmed that MgO nanoparticles synthesised at a precursor solution pH of 4 had uniform size distribution with a small microcrystalline size (∼19 nm) and spherical granular morphology. In addition, the results of the plate colony counting method showed that the antibacterial rate of MgO-4 against Gram-negative Escherichia coli (106 CFU/mL) at a sample concentration of 100 μg/mL was as high as 99.86 %, which showed excellent antibacterial performance. These findings provide valuable insights into how to increase the degree of oxygen adsorption on the sample surface to participate in the reaction, as well as a potential method for constructing nanomaterials with high antimicrobial activity.

Synthesis and antibacterial activity of silver doped zinc sulfide/chitosan bionanocomposites: A new frontier in biomedical applications

Numerous microbial species have caused infectious diseases worldwide, which have become a social burden and a menace to the community. So, there is a need to develop antimicrobial materials and specialized materials for biomedical applications. In the present investigation, we report the simple synthesis, the physicochemical, and antibacterial activity of Silver doped zinc sulfide (ZnS: Ag) capped with Chitosan (CS) to produce ZnS: Ag/CS bionanocomposites (BNCs). The prepared BNCs was evaluated by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) mapping, and UV–Vis spectroscopy. According to the XRD results, ZnS: Ag/CS particles with semicrystalline chitosan/hexagonal ZnS phase structures and an average crystallite size in the range of 30–40 nm was formed. According to FESEM images, a spherical/hexagonal shape of ZnS: Ag particles embedded in the polymeric chitosan matrix. The colony counting method was employed to investigate the antibacterial activity on Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. The results revealed that ZnS: Ag particles and ZnS: Ag/CS BNCs have stronger antibacterial activities than pure CS and ZnS. The reduction percentage of ZnS: Ag/CS BNCs against S. aureus and E. coli after 6 h of treatment was >99.9 % and 70 % respectively. These findings suggest that ZnS: Ag/CS BCs not only offer superior antimicrobial properties compared to individual ZnS and CS but also have great potential for advancing biomedical applications due to their enhanced antibacterial performance. The simplicity of the synthesis method and the use of non-toxic materials like chitosan make this a sustainable approach for developing antimicrobial agents, which is a key advantage of this study.

Humidity-responsive pectin/AgNPs/ZnO composite films with high antimicrobial and UV-proof functions

ZnO nanoparticles and Ag nanoparticles (AgNPs) tend to agglomerate when used individually, and high Ag+concentrations can cause cytotoxicity. To address these issues, we synthesized carboxymethyl cellulose (CMC)-based antimicrobial mimetic peptides (AMPMs) by introducing amphiphilic cations on the surface of CMC using a chemical grafting method. Bis-formaldehyde-formylated AMPMs were prepared through the directional oxidation of AMPMs with periodate and used as the reducing agent to synthesize AgNPs on the surface of pectin in situ for the preparation of a pectin/AgNPs/ZnO composite film. The physical and chemical properties of the films were characterized and analyzed by SEM (EDS), TEM, XRD, and UV spectroscopy. The results showed that the film's surface was smooth and flat, with small, well-stabilized AgNPs and uniformly dispersed ZnO. The film retained the original crystalline form of pectin, but exhibited altered crystallinity, indicating that the method employed was very mild. A systematic evaluation of the film’s antimicrobial performance using the dynamic growth curve, inhibition zone, and colony counting methods showed that AgNPs and ZnO imparted excellent, long-lasting antimicrobial activity to the film (98 %). Additionally, the films exhibited good flexibility, excellent ultraviolet protection (99.9 %), biocompatibility, and biodegradability. Notably, the film was sensitive to humidity, as demonstrated by its humidity-responsive bionic application. This study provides a promising reference and strategy for advancing the development of multifunctional polysaccharide-based nanocomposites.

Combinatory effect of ALA-PDT and itraconazole in the treatment of cutaneous protothecosis

BackgroundAs a rare subcutaneous infection, protothecosis is easily misdiagnosed. Similar to other subcutaneous infection, there is no unified standard for treatment, for cases not suitable for surgery, clinicians often use antifungal drugs based on their experience, and the course of treatment varies from several months to several years. Based on the fact that there are few relevant materials and researches on photodynamic therapy (PDT), we conducted a study based on a clinical case that used oral itraconazole combined with 5-aminolevylinic acid photodynamic therapy (ALA-PDT) to treat a patient with cutaneous protothecosis caused by Prototheca wicherhamii. MethodsDifferent concentrations of ALA and different light doses were used to investigate the effects of ALA-PDT on the growth inhibition of P. wickerhamii in vitro with Colony-counting Methods. And we used transmission electron microscopy (TEM) to visualize the structural changes and the effects of ALA-PDT treating on cellular structures of the P. wickerhamii. Futher, we performed the susceptibility test of P. wickerhamii to itraconazole before and after ALA-PDT in vitro. ResultsWe have successfully treated a patient with cutaneous protothecosis caused by P. wickerhamii by using combination therapy in a total of 9-week course of treatment. In vitro, ALA-PDT can inhibit the growth of P. wickerhamii when the ALA concentration was 5 mg/mL (P < 0.01), and this effect became stronger as the concentration of ALA or light dose is increased. Using TEM, we confirmed that ALA-PDT can disrupt the cell wall structure and partition structure of P. wickerhamii, which may contribute to its inhibitory effect. Further studies showed that the MIC of itraconazole for P. wickerhamii was decreased after ALA-PDT. ConclusionsALA-PDT combined with oral itraconazole can be used to treat cutaneous protothecosis. Accordingly, ALA-PDT can destroy the cell wall and partition structure of P. wickerhamii leading to an inhibitory effect on it in vitro, and the effect is enhanced with the increase of ALA concentration and light dose. Also, the sensitivity of P. wickerhamii to itraconazole is observed increased after ALA-PDT. So our study provides a theoretical basis for the promising treatment against cutaneus protothecosis.

Phytochemical-Based Nanoantioxidants Stabilized with Polyvinylpyrrolidone for Enhanced Antibacterial, Antioxidant, and Anti-Inflammatory Activities.

Despite the inhibitory effect of phytoncide (Pht) on food-borne pathogenic bacterial growth, the hydrophobic nature and susceptibility to biodegradation under physiological conditions limits its applications. Here, we developed Pht-loaded polyvinylpyrrolidone (PVP) micelles (Pht@PVP MC) via micelle packing. Pht was solubilized using different types of PVP as micellar vehicles. The as-prepared Pht@PVP MCs were characterized using dynamic light scattering and transmission electron microscopy. The sizes of the Pht@PVP MCs were controlled from 301 ± 51 to 80 ± 3 nm by adjusting the PVP content. The polydispersity index of Pht@PVP MC was between 0.21 ± 0.03 and 0.16 ± 0.04, indicating homogeneous size. A colony-counting method was employed to evaluate the improvement in antibacterial activity after Pht encapsulation in PVP micelles. The reactive oxygen species (ROS)-scavenging activity and anti-inflammatory efficacy of Pht@PVP MC were analyzed in a concentration range of 10-100 μg/mL by evaluating in vitro ROS and nitric oxide levels using DCFDA and Griess reagents. PVP with both hydrophobic and hydrophilic moieties improved the aqueous solubility of Pht and stabilized it via steric hindrance. Higher-molecular-weight PVP at higher concentrations resulted in a smaller hydrodynamic diameter of Pht@PVP MC with uniform size distribution. The spherical Pht@PVP MC maintained its size and polydispersity index in a biological buffer for 2 weeks. Pht@PVP MC exhibited enhanced antibacterial activity compared to bare Pht. The growth of Staphylococcus aureus was effectively inhibited by Pht@PVP MC treatment. Furthermore, biocompatible Pht@PVP MC exhibited dose-dependent antioxidant and anti-inflammatory activities in vitro. Overall, Pht@PVP MC is an effective alternative to synthetic antibacterial, antioxidant, and anti-inflammatory chemicals.

Effect of zinc oxide/graphene oxide nanocomposites on the cytotoxicity, antibacterial and mechanical properties of polymethyl methacrylate

BackgroundEnhancing the antibacterial properties of polymethyl methacrylate (PMMA) dental resins is crucial in preventing secondary infections following dental procedures. Despite the necessity for such improvement, a universally applicable method for augmenting the antibacterial properties of PMMA without compromising its mechanical properties and cytotoxicity remains elusive. Consequently, this study aims to address the aforementioned challenges by developing and implementing a composite material known as zinc oxide/graphene oxide (ZnO/GO) nanocomposites, to modify the PMMA.MethodsZnO/GO nanocomposites were successfully synthesized by a one-step procedure and fully characterized by TEM, EDS, FTIR and XRD. Then the physical and mechanical properties of PMMA modified by ZnO/GO nanocomposites were evaluated through water absorption and solubility test, contact angle test, three-point bending tests, and compression test. Furthermore, the biological properties of the modified PMMA were evaluated by direct microscopic colony count method, crystal violet staining and CCK-8.ResultsThe results revealed that ZnO/GO nanocomposites were successfully constructed. When the concentration of nanocomposites in PMMA was 0.2 wt. %, the flexural strength of the resin was increased by 23.4%, the compressive strength was increased by 31.1%, and the number of bacterial colonies was reduced by 60.33%. Meanwhile, It was found that the aging of the resin did not affect its antibacterial properties, and CCK-8 revealed that the modified PMMA had no cytotoxicity.ConclusionZnO/GO nanocomposites effectively improved the antibacterial properties of PMMA. Moreover, the mechanical properties of the resin were improved by adding ZnO/GO nanocomposites at a lower range of concentrations.

Electrospun nanofibrous membranes with functionalized 2D nanofillers for efficient micropollutant removal from water

In response to emerging challenges in water pollution, such as the contamination caused by dyes and antibiotics, scientists have been driven to develop state-of-the-art remediation techniques. The electrospun nanofiber membrane effectively eliminates antibiotics and dyes from industrial wastewater. This research work primarily centres on creating electrospun membranes based on polyacrylonitrile (PAN) nanofiber membranes and mixed matrix membranes (MMM), PAN@MMM-1 and PAN@MMM-2, crafted through the electrospinning process. Enhanced membrane performance has been achieved by incorporating functionalized clay materials, alginate-bentonite (Alg-Bnt) and lanthanum-bentonite (La-Bnt) nano clay, as nanofillers. These membranes offer a combination of ease of use, high efficiency, energy and cost savings, and an environmentally friendly and ecologically beneficial nature. The study conducted a comprehensive analysis of the materials and membranes using a range of advanced technologies such as Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectrometer (XPS), X-ray diffraction spectroscopy (XRD), and the plate colony counting method for assessing antibacterial activity. UV–visible spectroscopy and HPLC were employed to determine the concentrations of antibiotics and dye compounds in the feed and permeate. The results revealed that the PAN@MMM-1 membrane exhibited a water permeability value up to 18.8 L m−2 h−1 and achieved rejection rates of up to 99.08 % for BSA, 97.82 % for cephalexin, 98.23 % for diclofenac, and 97.24 % for sulfamethoxazole. Moreover, it demonstrated impressive rejection rates of 99.39 % for methyl orange and 96.77 % for methyl violet, highlighting its remarkable efficacy in purifying wastewater.

Assessing the antibacterial efficacy of nano propolis concentrations on Streptococcus mutans

Background: Dental caries is a common disease among the Indonesian population, with a prevalence of dental caries in Indonesia reaching 88.8%. Streptococcus mutans is one of the types of bacteria found in caries lesions. Nano propolis has antibacterial properties that can help inhibit the growth of Streptococcus mutans bacteria, reducing the risk of dental caries. Objective: This study aims to determine the effective concentration of nano propolis ranging from 2.5% to 0.625%. Methods: The research evaluates various concentrations of nano propolis, and the minimum concentration that inhibits the growth of Streptococcus mutans is observed using the colony count method. Results: The growth of Streptococcus mutans at a concentration of 2.5% nano propolis was 0, at 1.8% it was 6, at 1.25% it was 11.4, and at 0.625% it was 42. The positive control group containing BHIB media and Streptococcus mutans bacteria showed an average colony growth of 161. Conclusion: Nano propolis at a concentration of 1.25% is effective in inhibiting the growth of Streptococcus mutans.

Surface modification of polyacrylonitrile nanofiber membrane by Bimetallic organic frameworks for enhanced antibacterial properties

With the increasing environmental degradation, bacterial contamination is threatening human health. Thus, it is crucial to develop an efficient and safe antimicrobial strategy. In this work, the polyacrylonitrile (PAN) nanofiber membranes contained Co/Zn-metal organic framework (Co/Zn-MOF@PAN) were fabricated via electrospinning technique and surface modified method. The optimal preparation condition for nanofiber membranes were further regulated by adjusting 2-methylimidazole (2-MIM) concentration and secondary growth time. The antibacterial activity of Co/Zn-MOF@PAN against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were determined by turbidimetry and plate colony-counting methods. As the 2-MIM concentration and secondary growth time increased, the hydrophilicity and surface roughness of Co/Zn-MOF@PAN nanofiber membranes increased. In addition, when the 2-MIM concentration was 0.16 mol/L, the Co/Zn-MOF@PAN nanofiber membranes had an antibacterial rate of over 99% against E. coli and S. aureus., and the minimum inhibitory concentration (MIC) value of Co/Zn-MOF@PAN nanofiber membranes was 0.75 mg/mL. It could be indicated that Co/Zn-MOF@PAN nanofiber membranes exhibited an excellent antibacterial effect. The main antibacterial mechanism of nanofiber membranes was that ROS produced by MOFs could destroy the physiological activities of the bacteria lead to death. The Co/Zn-MOF@PAN nanofiber membranes will have a wide range of applications value in the fields of antibacterial packaging materials and sterilization of water resources.

Characterization of heat, salt, acid, alkaline, and antibiotic stress response in soil isolate Bacillus subtilis strain PSK.A2.

Microbes play an essential role in soil fertility by replenishing the nutrients; they encounter various biotic and abiotic stresses disrupting their cellular homeostasis, which expedites activating a conserved signaling pathway for transient over-expression of heat shock proteins (HSPs). In the present study, a versatile soil bacterium Bacillus subtilis strain PSK.A2 was isolated and characterized. Further, the isolated bacterium was exposed with several stresses, viz., heat, salt, acid, alkaline, and antibiotics. Stress-attributed cellular morphological modifications such as swelling, shrinkage, and clump formation were observed under the scanning electron microscope. The comparative protein expression pattern was studied by SDS-PAGE, relative protein stabilization was assessed by protein aggregation assay, and relative survival was mapped by single spot dilution and colony-counting method under control, stressed, lethal, and stressed lethal conditions of the isolate. The findings demonstrated that bacterial stress tolerance was maintained via the activation of various HSPs of molecular weight ranging from 17 to 115 kD to respective stimuli. The treatment of subinhibitory dose of antibiotics not interfering protein synthesis (amoxicillin and ciprofloxacin) resulted in the expression of eight HSPs of molecular weight ranging from 18 to 71 kD. The pre-treatment of short stress dosage showed endured overall tolerance of bacterium to lethal conditions, as evidenced by moderately enhanced total soluble intracellular protein content, better protein stabilization, comparatively over-expressed HSPs, and relatively enhanced cell survival. These findings hold an opportunity for developing novel approaches towards enhancing microbial resilience in a variety of conditions, including industrial bioprocessing, environmental remediation, and infectious disease management.

Hydrothermally synthesized biofunctional ceria nanoparticles using orange peel extract: optimization, characterization, and antibacterial and antioxidant properties.

In this research, cerium oxide nanoparticles were synthesized using orange peel extract via a hydrothermal method. An equal ratio of orange peel extract to cerium nitrate salt led to the formation of cerium hydroxide carbonate, whereas a 1 : 10 ratio formed cerium oxide. The hydrothermal treatment was conducted for durations of 5 and 25 hours. Scanning electron microscopy (SEM) images revealed that the hydrothermal samples treated for 5 hours exhibited significant agglomeration in both extract to salt ratios after heat treatment. X-ray diffraction patterns confirmed that all samples were converted into cerium oxide after heating at 500 °C for 3 hours. Based on XRD and SEM results, three cerium oxide samples, including those synthesized through the 25 hours hydrothermal process with a 1 : 10 ratio and the 25 hours hydrothermal process with both ratios and subsequent heat treatment, were selected for further investigation. Fourier transform infrared (FT-IR) analysis revealed more adsorption of the functional groups of orange peel extract on the surface of the as-synthesized sample. Moreover, the heat-treated sample with a 1 : 10 ratio, initially cerium oxide, displayed a higher amount of surface functional groups than the one with a 1 : 1 ratio which was initially cerium hydroxide carbonate. The antibacterial activities of the samples were determined using the colony count method. Activities of all samples against Gram-negative bacteria are in the range of 91.5-93.2% with a negligible difference, whereas the as-synthesized sample exhibited a superior activity of 96.6 ± 1.8% against Gram-positive bacteria compared to the other two heat-treated samples. The 87.3% antioxidant activity of the as-synthesized sample significantly surpassed that of the other two samples, as evaluated by the DPPH radical scavenging method.

Extraction of Nanocellulose from the Residue of Sugarcane Bagasse Fiber for Anti-Staphylococcus aureus (S. aureus) Application.

Nanocellulose contains a large number of hydroxyl groups that can be used to modify its surface due to its structure. Owing to its appealing features, such as high strength, great stiffness, and high surface area, nanocellulose is currently gaining popularity in research and industry. The extraction of nanocellulose from the leftover bagasse fiber from sugarcane production by alkaline and acid treatment was successful in this study, with a production yield of 55.6%. The FTIR and XPS results demonstrated a difference in the functional and chemical composition of untreated sugarcane bagasse and extracted nanocellulose. SEM imaging was used to examined the size of the nanocellulose with ImageJ software v1.8.0. TGA, DTG, and XRD analyses were also performed to demonstrate the successful extraction of nanocellulose in terms of its morphology, thermal stability, and crystal structure before and after extraction. The anti-S. aureus activity of the extracted nanocellulose was discovered by using an OD600 test and a colony counting method, and an inhibitory rate of 53.12% was achieved. According to the results, nanocellulose produced from residual sugarcane bagasse could be employed as an antibacterial agent.

Antibacterial properties of reduced graphene oxide fibers fabricated by hydrothermal method

The antibacterial activity of reduced graphene oxide fibers (rGOFs) fabricated by a one-step dimensionally confined hydrothermal technique was investigated on both Gram-positive and Gram-negative models of bacteria in this study. The surface morphology, microstructure, and chemical composition of the as-prepared rGOFs were determined using scanning electron microscopy (SEM), X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. SEM images showed the fiber to have an average diameter of 46.6 ± 0.53 μm, composed of rGO nanosheets with numerous sharp edges. XPS and Raman spectroscopy confirmed the presence of sp3-bonded carbon and structural defects in the samples. Antibacterial properties of rGOFs were tested and analyzed using agar well diffusion, colony counting method, SEM observation, and reactive oxygen species generation. The excellent broad-spectrum antibacterial ability of rGOFs is attributed to the physicochemical properties and unique surface morphological features of the samples, which could facilitate the development of rGOFs-based biomaterial for various biomedical and nano-technological applications such as a promising antibacterial agent or an implant/scaffold for nerve tissue engineering and regeneration.

Investigation of gamma radiation shielding and antimicrobial properties of PbO-doped ZnO and TiO2 composites

Gamma radiation is utilized in various fields, such as food shelf-life preservation, medicine, and industry. The protection against ionizing radiation, such as gamma radiation, is a crucial matter. Ionizing radiation is harmful to both the environment and living organisms, leading to cellular mutations, organ damage, equipment malfunctions, and other adverse effects. To achieve radiation protection, shielding methods are employed. Materials that prevent bacterial growth and contamination should also be developed in all areas. In our study, glass substrates were coated using the rotational coating method. In this study, the antimicrobial and radiation protection properties of glass coatings prepared with ZnPb (50% ZnO + 50% PbO) and TiPb (50% TiO2 + 50% PbO) ratios were investigated. For radiation protection properties, mass attenuation coefficient (MAC) values were calculated using the Geant4-GATE and XCOM simulations, and the results were compared with the experimental data. Calculations were performed at 511, 662, 1173, 1274, and 1332 keV energy levels. A colony counting method was employed to determine the antibacterial effectiveness of Pb-doped TiO2 and ZnO. The antibacterial efficacy of Pb-doped TiO2 and ZnO films was tested against Staphylococcus aureus (ATCC 25923) and Escherichia coli (ATCC 25922) bacteria. It was found that these films were effective only against Staphylococcus aureus bacteria. The antimicrobial efficiency of the nanocomposites was evaluated against various bacterial strains, highlighting significant inhibitory properties, particularly for TiO2 and ZnO nanocomposites against S. aureus. This emphasizes their potential as antimicrobial agents.

Variability and health impact of air pollutants and bioaerosols in multi-functional indoor environments with mechanical ventilation system

The condition of indoor environments significantly impacts human daily life and health, where exposure to harmful substances affects the resilience of occupants. To understand the dynamics of indoor air quality and its implications for occupant health thus this study evaluated air pollutant concentration (TVOC, NO2, O3, CO, CO2, PM10, PM2.5, and PM1) and bioaerosol in mechanically ventilated offices, laboratories, corridors, a library and a mechanical workshop. Simultaneous measurements of all air pollutants were performed for 24 h, including non-working hours, while bioaerosol was sampled for fungal identification and quantified via the colony counting method. High concentrations of PM10, PM2.5, PM1, O3 and bioaerosol were found in the mechanical workshop, where these pollutants were strongly related to humidity (p < 0.05) and indoor source contributions. Other air pollutants such as TVOC had the highest concentrations in the office areas during working hours with an average concentration of 361 ± 14.8 μg m−3, while for CO, the highest concentration was observed in the laboratories for both working hours (442 ± 26.0 ppb) and 24 h average concentration (438 ± 22.1 ppb). Dominant species identified in bioaerosol were Aspergillus sp., Geotrichum sp., Fusarium sp., and Penicillium sp., where the exposure to bioaerosol was found to be of low risk to all workers as the hazard quotient (HQ) was <1 for all multi-functional indoor environments. The results from this study suggest that indoor air pollutants and bioaerosol concentrations have a variety of characteristics and source contributions, especially from human activities and indoor sources.

Synthesis of Silver‐Doped Titanium Dioxide Nanoparticles by Sol‐Gel and Coprecipitation Techniques: Evaluation of Antimicrobial Activity and Cytotoxic Effects

AbstractTiO2 nanoparticles are effective alternative to the antibiotics. The quick recombination of the photogenerated charges and the inefficient exploitation of visible light remain the major problems limiting their large‐scale applications. Modifying the TiO2 with Silver that acting as an electron trap, plays an important role in reducing the recombination of TiO2 charges and shift its photo‐response to the visible light region. The present work aims to synthesize AgTiO2 nanoparticles using sol‐gel and coprecipitation methods and evaluating the antimicrobial behavior of them. Also, to find the optimal conditions based on the anatase phase of TiO2 due to its higher antimicrobial activity than the rutile form. Among Ag‐TiO2 nanoparticles obtained, the one prepared by sol‐gel method at 450 °C and PH=8–8.5 exhibits the best antimicrobial property. AgTiO2 nanoparticles have been characterized by means X‐ray Diffraction (XRD), Fourier transform infrared spectroscopy (FTIR),scanning electron microscope (SEM), ζ‐potential, dynamic light scattering (DLS) that showing promising results. Zeta potential values −103 mV has been reported that is considered as a stable colloidal suspension system that prevents nanoparticles aggregation. Antimicrobial behavior of them were evaluated using Diffusion (Agar disk‐diffusion), Dilution (MIC) and Bacterial colony counting methods and diameter of the inhibitory zone 15 mm and minimum inhibitory concentration 5 mg/ml was observed.Colony count results indicated that AgTiO2 able to kill bacteria at the lowest concentration of 5 mg/ml. Outcomes of MTT assay (measure cell cytoxicity) suggesting the absence of toxicity in living Hfff cells (as a normal human fibroblast) while surviving L929 cells (as a cancer cell line originated from mouse fibroblast cells). After 24 and 48 h incubation from 100 % to 77.3 % and 57.2 % was reduced respectively. This indicates that Ag/TiO2 nanoparticles act as a anticancer drug and have inherent selective toxicity nature towards cancer cells while posing no effect to normal cells. AgTiO2 nanoparticles are synthesized using sol‐gel and coprecipitation methods. The sample prepared by the sol‐gel method at a temperature of 450 °C and pH=8.5, which corresponds to the anatase phase of TiO2 synthesis, shows the best antimicrobial properties and acts as an anticancer drug with inherent selective toxicity nature towards cancer cells while posing no effect on normal cells.

Effectiveness biduri leaf extract (Calotropis gigantea) as a denture cleanser in acrylic immersion against the growth of Candida albicans: an experimental laboratory

ABSTRACTIntroduction: The high number of cases of tooth loss in Indonesia has led to the emergence of dentures. Dentures not appropriately kept clean can trigger cases of denture stomatitis due to Candida albicans. C. albicans is often detected on denture plates and causes denture stomatitis. Cleaning the dentures can prevent denture stomatitis, and chemical cleaning often uses synthetic materials such as alkaline peroxide. However, alkaline peroxide can cause side effects in the form of increased porosity on the surface of the acrylic plate, so an alternative natural ingredient, namely biduri leaves (Calotropis gigantea), is needed because it has various active compounds such as alkaloids, flavonoids, phenols, saponins, terpenoids and tannins which have antifungal effects. This study aimed to determine the effective inhibitory power of biduri leaf extract as a denture cleanser in acrylic immersion against the growth of C. albicans. Methods: Biduri leaves were extracted using the maceration method with 70% ethanol solvent to produce varying concentrations of 20, 30, 40, and 50%. The sample used in this research was an acrylic plate measuring 10x10x1 mm, soaked in artificial sterile saliva for 1 hour, then soaked in each sample group for 8 hours, after that it was placed in 10 ml of Sabouraud Dextrose Broth (SDB) media, and vibrated for 30 seconds using a mixing vortex, spreading 0,1ml SDB on Saboraud Dextrose Agar (SDA) and incubated for 48 hours. The growth of C. albicans was observed and counted using the colony counting method. Result: This research showed an inhibitory power of biduri leaf extract in concentrations of 20, 30, 40, and 50% on the growth of C. albicans, with a concentration of 50%, having the most significant inhibitory power. Conclusion: Biduri leaf extract as a denture cleanser has an inhibitory power on the growth of C. albicans.KEYWORDS Biduri leaves, Calotropis gigantea, heat cured acrylic, Candida albicans

Antibacterial potential of Biduri leaf extract (Calotropis gigantea) against the growth of Streptococcus mutans ATCC 35668 colonies: an experimental laboratory

ABSTRACTIntroduction: Caries is an oral cavity infection that attacks the hard tissue of the teeth. Caries are caused by cariogenic bacteria such as Streptococcus mutans (S.mutans). S.mutans plays a role in the process of biofilm and plaque build up. One alternative ingredient that has antibacterial properties is Biduri leaves (Calotropis gigantea). The research aimed to analyze the antibacterial potential of Biduri leaf extract on the growth of S.mutans colonies. Methods: This type of research is a laboratory experimental research in vitro using the post-test-only control group design method. The antibacterial test used the colony counting method. The extraction process used the maceration method for 1 day with a shaker. The concentrations used were concentrations of 20, 40, and 60%. Control (+) used 0.2% chlorhexidine and control (-) used distilled water. Incubation process was for 24 hours. Counting the growth of S.mutans colonies using a colony counter was carried out by three observers. Data analysis used the Kruskal-Wallis test followed by the Mann-Whitney test. Results: The results showed that there was a significant difference in the growth of S.mutans (p&lt;0.05) after being exposed to Biduri leaf extract at a concentration of 20, 40, and 60%. Conclusion: The Biduri leaf extract has antibacterial potential against S.mutans at concentrations of 20, 40, and 60%, and the best concentration in reducing the growth of S.mutans colonies is the concentration of 60%.KeywordsAntibacterial, Calotropis gigantea, 0.2% chlorhexidine, colony counting, Streptococcus mutans