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1.
Chemistryselect ; 8(21), 2023.
Article in English | Web of Science | ID: covidwho-20242400

ABSTRACT

This work sheds light on the effect of boswellic acid compounds (Alpha boswellic acid, Beta boswellic acid, 11-keto beta boswellic acid and 3-Acetyl-11-keto beta boswellic acid) upon inhibiting SARS-CoV-2 M-pro and O-M-pro (Main protease). A good docking score (-8.4 kcal/mol) is found in the case of 3-Acetyl-11-keto beta boswellic acid as compared to the reference and three other boswellic acid compounds. ADMET results suggest that all these compounds are nontoxic and their pharmacokinetic properties are satisfactory. Moreover, a stability analysis with M-pro/O-M-pro through RMSD, RMSF, hydrogen bonds and Rg parameters in MD simulations is made and we found better values than the reference case. Pre and post-MD structures of Ligands-M-pro show a similar binding site whereas a drift can be noted for L-O-M-pro. 3-Acetyl-11-keto beta boswellic acid shows an average of five hydrogen bonds and it remains stable within the binding pocket of M-pro during the simulation period in comparison to other boswellic acids compounds. Various metastable conformations are observed for all compounds in FEL (free energy landscape), however, Acyclovir-M-pro, Alpha boswellic acid-M-pro and Beta boswellic acid-O-M-pro display only one global minimum. The results suggest that these compounds can be used as potential lead molecules for breakthroughs in drug discovery.

2.
Journal of Nepalese Prosthodontic Society ; 5(1):44-50, 2022.
Article in English | EMBASE | ID: covidwho-2327177
3.
Topics in Antiviral Medicine ; 31(2):215-216, 2023.
Article in English | EMBASE | ID: covidwho-2314219

ABSTRACT

Background: The rapid emergence of the SARS-CoV-2 Omicron variant that evades many therapies illustrates the need for antiviral treatments with high genetic barriers to resistance. The small molecule PAV-104, identified through a moderate-throughput screen involving cell-free protein synthesis, was recently shown to target a subset of host protein assembly machinery in a manner specific to viral assembly with minimal host toxicity. The chemotype shows broad activity against respiratory viral pathogens, including Orthomyxoviridae, Paramyxoviridae, Adenoviridae, Herpesviridae, and Picornaviridae, with low susceptibility to evolutionary escape. Here, we investigated the capacity of PAV-104 to inhibit SARS-CoV-2 replication in human airway epithelial cells (AECs). Method(s): Dose-dependent cytotoxicity of PAV-104 in Calu-3 cells was determined by MTT assay. Calu-3 cells were infected with SARS-CoV-2 isolate USA-WA1/2020 (MOI=0.01). Primary AECs were isolated from healthy donor lung transplant tissue, cultured at air liquid interface (ALI), and infected with SARS-CoV-2 Gamma, Delta, and Omicron variants (MOI=0.1). SARS-CoV-2 replication was assessed by RT-PCR quantitation of the N gene, immunofluorescence assay (IFA) of nucleocapsid (N) protein, and titration of supernatant (TCID50). Transient co-expression of four SARS-CoV-2 structural proteins (N, M, S, E) to produce virus-like particles (VLPs) was used to study the effect of PAV-104 on viral assembly. Drug resin affinity chromatography was performed to study the interaction between PAV-104 and N. Glycerol gradient sedimentation was used to assess N oligomerization. Total RNA-seq and the REACTOME database were used to evaluate PAV-104 effects on the host transcriptome. Result(s): PAV-104 reached 50% cytotoxicity in Calu-3 cells at 3732 nM (Fig.1A). 50 nM PAV-104 inhibited >99% of SARS-CoV-2 infection in Calu-3 cells (p< 0.01) and in primary AECs (p< 0.01) (Fig.1B-E). PAV-104 specifically inhibited SARS-CoV-2 post entry, and suppressed production of SARS-CoV-2 VLPs without affecting viral protein synthesis. PAV-104 interacted with SARS-CoV-2 N and interfered with N oligomerization. Transcriptome analysis revealed that PAV-104 treatment reversed SARS-CoV-2 induction of the interferon and maturation of nucleoprotein signaling pathways. Conclusion(s): PAV-104 is a pan-respiratory virus small molecule inhibitor with promising activity against SARS-CoV-2 in human airway epithelial cells that should be explored in animal models and clinical studies.

4.
Current Traditional Medicine ; 9(6) (no pagination), 2023.
Article in English | EMBASE | ID: covidwho-2302974

ABSTRACT

Ferula asafoetida is an endemic species in Iran and is rich in oleo-gum resin with high economic value in the world. One important application of F. assafoetida is its traditional use for the management of respiratory ailments. The aim of this review was to collect papers dealing with F. asafoetida oleo-gum resin in respiratory tract's diseases in modern medicine. For preparing the manuscript the scientific databases (Google scholar, PubMed, Springer, Science Direct, Magiran), books, thesis, etc. were searched using the keywords of "Ferula asafoetida", "Ferula scorodesma", "Scorodesma foetida", "Northex asafoetida" plus "respiratory tract", "respiratory disorder" "infection", "cough", "trachea", "traditional medicine" up to Feb 2022 and the collected data were sum-marized, analyzed, and discussed. The results of the investigation confirmed the traditional belief on the efficacy of Ferula asafoetida in the treatment of respiratory viral infection (Coronavirus, influ-enza), cigarette smoking, asthma, cough and cancer, but most studies were limited to in vitro. There was only one registered randomized, blinded, placebo controlled clinical trial for 300 mg F. asafoet-ida aqueous extract capsules (three times a day for 14 days) on 40 patients with COVID-19 without any published results. Although, the studies implied the efficacy of F. asafoetida in the treatment of respiratory treatments, but design large clinical studies for evaluating its efficacy and safety is essential in future investigations.Copyright © 2023 Bentham Science Publishers.

5.
European Journal of Molecular and Clinical Medicine ; 7(11):8564-8569, 2020.
Article in English | EMBASE | ID: covidwho-2300444

ABSTRACT

Purpose: Intraoral defects in the maxilla cause communication with the nasopharyngeal complex. The surgically removed palate can have a devastating effect on the appearance and speech of the patient. Obturators allow patients to eat and drink without any suspicion of food entering the oroantral cavities/ pharynx during mastication. This clinical report describes fabrication of a closed hollow bulb obturator using the two-piece double flask technique. Method(s): After the final teeth arrangement was completed, teeth over the defect were removed and separately processed using heat cure acrylic resin. Both the segments are combined by autopolymerizing acrylic resin to form a single hollow-bodied obturator. Conclusion(s): This technique uses a double flasking method of the two segments to control the thickness of the bulb in the defect area, thus decreasing the weight of the obturator.Copyright © 2020 Ubiquity Press. All rights reserved.

6.
Nanomaterials (Basel) ; 13(7)2023 Mar 28.
Article in English | MEDLINE | ID: covidwho-2293653

ABSTRACT

Co-abietate and Cu-abietate complexes were obtained by a low-cost and eco-friendly route. The synthesis process used Pinus elliottii resin and an aqueous solution of CuSO4/CoSO4 at a mild temperature (80 °C) without organic solvents. The obtained complexes are functional pigments for commercial architectural paints with antipathogenic activity. The pigments were characterized by Fourier-transform infrared spectroscopy (FTIR), mass spectrometry (MS), thermogravimetry (TG), near-edge X-ray absorption fine structure (NEXAFS), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and colorimetric analysis. In addition, the antibacterial efficiency was evaluated using the minimum inhibitory concentration (MIC) test, and the antiviral tests followed an adaptation of the ISO 21702:2019 guideline. Finally, virus inactivation was measured using the RT-PCR protocol using 10% (w/w) of abietate complex in commercial white paint. The Co-abietate and Cu-abietate showed inactivation of >4 log against SARS-CoV-2 and a MIC value of 4.50 µg·mL-1 against both bacteria Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). The results suggest that the obtained Co-abietate and Cu-abietate complexes could be applied as pigments in architectural paints for healthcare centers, homes, and public places.

7.
Letters in Drug Design and Discovery ; 20(4):386-407, 2023.
Article in English | EMBASE | ID: covidwho-2285465

ABSTRACT

Background: Phytochemicals and their derivatives/analogues represent over 50% of the current medicines worldwide in clinical use. Despite a significant contribution to the total bioactive natural plant products, aquatic plants are underestimated, and several species are extinct and in the endangered list. Objective(s): The aim of this review article is to draw the attention of common people and scientists toward a few important contributions of the aquatic plants to natural product chemistry and drug discovery by highlighting the chemical and pharmaceutical aspects of the same. Method(s): The presented data were collected and selected from the literature obtained by an online search for the ethnomedicinal properties, biological activities and bioactive chemical constituents of aquatic plants using Google Scholar, PubMed and Scifinder chemical abstract service. Result(s): The selected literature data revealed that the extract and compounds isolated from several aquatic plants possess significant biological/pharmaceutical properties. For example, the alpha-asarone (24) and asiatic acid (33) isolated from Acorus calamus and Centella asiatica, respectively, exhibited significant neuroprotective effects in vitro and in vivo. The cripowellin A (59), cripowellin C (60), cripowellin B (61) and cripowellin D (62), isolated from Crinum erubescens, exhibited potent antiplasmodial and antiproliferative activities with half maximal inhibitory concentration (IC50) in nanomolar range (11-260 nM). Several other alkaloids from different Crinum species have also shown anticancer properties against different cancer cell lines with IC50 value <5 microM. Alkaloids and resin glycosides, isolated from different Ipomoea species, have displayed significant psychotropic, psychotomimetic, anticancer, and antibacterial activities with IC50 value <5 microM. Conclusion(s): The aquatic plants play a significant role in the discovery of bioactive natural products. Although several biological activities and bioactive compounds have been reported from these plants, further assessment and scientific validation of most of their traditional usages still need to be done. There are several other similar species that are underestimated and not much explored. Many aquatic plants, such as Ipomoea carnea Jacq., Juncus lomatophyllus Spreng., Commelina benghalensis Linn, Gunnera perpensa L., Scirpus maritimus L. and Mentha longifolia (L.) L., may be considered for further evaluation. In addition to these, one should not undermine the potential of Crinum macowanii for COVID-19 pathogenesis, as its chemical constituent lycorine has shown significant SARS-CoV-2 inhibitory potential (EC50, 0.3 muM;SI >129). Furthermore, most rural communities are still using the wetland resources for their cultural, medicinal, economic, domestic, and agricultural needs. Hence, the conservation of aquatic plants and wetlands is an issue of great concern.Copyright © 2023 Bentham Science Publishers.

8.
Journal of Pharmaceutical Negative Results ; 13:2212-2218, 2022.
Article in English | EMBASE | ID: covidwho-2284527

ABSTRACT

Background: Oroantral communication can occur due to maxillectomy defects, jeopardizing the integrity and function of oral cavity. It is an interdisciplinary challenge to restore these by surgery and prosthetics since many facets need to be addressed, such as speech, deglutition, mastication, aesthetics and psychological distress. Rationale: Surgical repair of maxillectomy defects is not always achievable due to various reasons such as poor systemic health, advanced age etc. Thus prosthetic rehabilitation becomes the most suitable treatment option. Relevance for Patients: Post COVID-19 mucormycosis has seen a surge in the past two years. It is an opportunistic fungal infection in humans infecting intracranial structures by direct invasion in the blood stream. Fundamental goal of prosthetic rehabilitation is the closure of oronasal communication and restoring it functionally thereby improving quality of life for the patient. CAD/CAM (computer aided design/computer aided milling) technology was employed to fabricate a milled framework for maxillary obturator in the most innovative way using PEEK (Polyether ether ketone). Result(s): PEEK material due to its excellent biocompatibility ensured a light weight prosthesis for the large maxillectomy defect and closure of the patency was achieved by the obturator framework.Copyright © 2022 Authors. All rights reserved.

9.
Bulletin of the Plankton Society of Japan ; 69(1):34-38, 2022.
Article in Japanese | Scopus | ID: covidwho-2279396

ABSTRACT

In recent years, learning styles involving observation and experimentation have been recommended for schools as a form of active learning. The National Institute of Polar Research is promoting the improvement and increased production of resin-embedded zooplankton specimens for use in marine education. Based on trials and questionnaires completed by current teachers, we created a marine educational workshop kit comprising resin-embedded specimens, observation tools, a booklet, worksheets, introductory videos for participants, and workshop programs. The kit is designed mainly for junior high school students and can be used for remote (online) workshops to facilitate online learning necessitated by the COVID-19 pandemic. We have requested school teachers to try using the kit and identify various applications of the kit. We began loaning out the kits in November 2021. We hope that many teachers who have not had the chance to conduct marine education will start using this kit. © 2022 Plankton Society of Japan. All rights reserved.

10.
Bulletin of the Plankton Society of Japan ; 69(1):34-38, 2022.
Article in Japanese | Scopus | ID: covidwho-2279395

ABSTRACT

In recent years, learning styles involving observation and experimentation have been recommended for schools as a form of active learning. The National Institute of Polar Research is promoting the improvement and increased production of resin-embedded zooplankton specimens for use in marine education. Based on trials and questionnaires completed by current teachers, we created a marine educational workshop kit comprising resin-embedded specimens, observation tools, a booklet, worksheets, introductory videos for participants, and workshop programs. The kit is designed mainly for junior high school students and can be used for remote (online) workshops to facilitate online learning necessitated by the COVID-19 pandemic. We have requested school teachers to try using the kit and identify various applications of the kit. We began loaning out the kits in November 2021. We hope that many teachers who have not had the chance to conduct marine education will start using this kit. © 2022 Plankton Society of Japan. All rights reserved.

11.
Journal of Health and Translational Medicine ; 25(2):156-161, 2022.
Article in English | EMBASE | ID: covidwho-2263792

ABSTRACT

Lateral luxation injuries are common during childhood and in young adolescence. These injuries involve the surrounding tissues that could lead to extensive clinical treatment problems with a risk of pulpal complications such as pulp necrosis. A case of a healthy 4-year-old Malay boy visiting the paediatric dental clinic after seven months of laterally luxated injury on the lower right lateral incisor (tooth 82) was reported. The traumatic tooth was splinted by a private practitioner three days after the trauma, however, the splint dislodged less than 24-hour after placement. In view of the mother's fear of bringing her child to the dentist due to the COVID-19, no follow-up and further treatment were carried out. This has resulted in the development of discolouration and pulpal necrosis to the injured tooth. Lesion sterilization and tissue repair technique (LSTR) was performed. This report highlights the rare occurrence of lateral luxation injury on tooth 82 and the management of pulp necrosis as a complication via lesion sterilization and tissue repair technique due to the uncooperative behaviour of the child.Copyright © 2022, Faculty of Medicine, University of Malaya. All rights reserved.

12.
European Respiratory Journal ; 43(5):716-721, 2022.
Article in English | EMBASE | ID: covidwho-2262867

ABSTRACT

Aim: This study aimed at the species identification of selected indigenous earthworms of Manipur and Assam, Northeast India along with an exotic species using morpho-anatomical study and DNA barcoding. Methodology: Indigenous species of earthworms were collected from Imphal and Jorhat, North-eastern part of India. The exotic species of earthworm were collected from Indian Council of Agricultural Research Complex, Manipur. The samples were collected by digging and hand sorting method. Identification of samples was done by both conventional and molecular methods. Molecular characterization was accomplished through PCR amplification of the mitochondrial cytochrome oxidase I (COI) genes. Automatic sequencing reactions were performed for the amplified PCR products on ABI3100 Genetic Analyser (Applied Biosystems). Result(s): Out of five specimens (EM1, EM2, EM4, EG5 and EM6) examined through morpho-anatomical studies, three were identified to species level while the other two were identified to their genus level only. Out of EM1 and EM2 specimens in the genus Perionyx as per the morpho-anatomical studies, DNA barcoding could deduce the EM2 specimen up to the species level as P. excavatus. The exotic EM6 specimen morphologically identified as Eisenia fetida showed 99% COI gene sequence similarity with both E. fetida and E. andrei but its sequence divergence with E. andrei was less than 1%, so, it belonged to E. andrei. Interpretation(s): This study shows the reliability of clubbing DNA barcoding experiments with classical taxonomy in supplementing and strengthening the traditional taxonomy for accurate identification of earthworms.Copyright © Triveni Enterprises, Lucknow (India)

13.
Cureus ; 15(3): e36394, 2023 Mar.
Article in English | MEDLINE | ID: covidwho-2254090

ABSTRACT

BACKGROUND AND AIM: It is important to provide appropriate dental care for newly erupted permanent first molars (PFMs) since they are susceptible to caries. As the coronavirus disease 2019 (COVID-19) pandemic has led to significant changes in the way dental services are provided to patients, the purpose of this study is to examine the procedure records assigned to PFMs of 6-15 year-olds during the pandemic and analyze the restorative material preferences of the residents of public dental hospitals. MATERIALS AND METHODS: Procedure records of patients aged between 6-15 years were extracted from the Public Oral and Dental Health Center, Bursa, Türkiye. All teeth groups except PFMs were excluded, while extracted, survived (restorative/endodontic/prosthetic procedures), and prevented (fissure sealant application) PFMs were analyzed retrospectively. Furthermore, restorative material preferences were analyzed by arch location, cavity surfaces, and dentition types. RESULTS: Strong positive correlation was seen between age and PFM extraction (r=0.973; p<0.001) and age and PFM restorative treatments (r= 0.966; p<0.001); a negative correlation was detected between age and fissure sealants (r= -0.984; p<0,001) performed on PFMs of 8-15-year-olds. Amalgam was most often preferred as the restorative material (p<0.05). CONCLUSION: The distribution of treatments and dental restorations can vary based on many factors, and the pandemic conditions may have changed treatment preferences to favor preventive dentistry. The excess of multi-surface restorations may be related to the delay of treatment applications during COVID-19.

14.
Methods in Molecular Biology ; 2578:53-62, 2023.
Article in English | Scopus | ID: covidwho-2243611

ABSTRACT

Recent advances in biosensing analytical platforms have brought relevant outcomes for novel diagnostic and therapy-oriented applications. In this context, 3D droplet microarrays, where hydrogels are used as matrices to stably entrap biomolecules onto analytical surfaces, potentially provide relevant advantages over conventional 2D assays, such as increased loading capacity, lower nonspecific binding, and enhanced signal-to-noise ratio. Here, we describe a hybrid hydrogel composed of a self-assembling peptide and commercial agarose (AG) as a suitable matrix for 3D microarray bioassays. The hybrid hydrogel is printable and self-adhesive and allows analyte diffusion. As a showcase example, we describe its application in a diagnostic immunoassay for the detection of SARS-CoV-2 infection. © 2023, The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.

15.
J Funct Biomater ; 14(1)2022 Dec 22.
Article in English | MEDLINE | ID: covidwho-2234080

ABSTRACT

There has been profound growth in the use of 3D printed materials in dentistry in general, including orthodontics. The opportunity to impart antimicrobial properties to 3D printed parts from existing resins requires the capability of forming a stable colloid incorporating antimicrobial fillers. The objective of this research was to characterize a colloid consisting of a 3D printable resin mixed with Ag-ion releasing zeolites and fumed silica to create 3D printed parts with antiviral properties. The final composite was tested for antiviral properties against SARS-CoV-2 and HIV-1. Antiviral activity was measured in terms of the half-life of SARS-CoV-2 and HIV-1 on the composite surface. The inclusion of the zeolite did not interfere with the kinetics measured on the surface of the ATR crystal. While the depth of cure, measured following ISO4049 guidelines, was reduced from 3.8 mm to 1.4 mm in 5 s, this greatly exceeded the resolution required for 3D printing. The colloid was stable for at least 6 months and the rheological behavior was dependent upon the fumed silica loading. The inclusion of zeolites and fumed silica significantly increased the flexural strength of the composite as measured by a 3 point bend test. The composite released approximately 2500 µg/L of silver ion per gram of composite as determined by potentiometry. There was a significant reduction of the average half-life of SARS-CoV-2 (1.9 fold) and HIV-1 (2.7 fold) on the surface of the composite. The inclusion of Ag-ion releasing zeolites into 3D-printable resin can result in stable colloids that generate composites with improved mechanical properties and antiviral properties.

16.
Int Dent J ; 2022 Oct 20.
Article in English | MEDLINE | ID: covidwho-2076168

ABSTRACT

OBJECTIVE: The aim of this research was to investigate the effect of various mouthwashes for COVID-19 prevention on surface hardness, roughness, and colour changes of bulk-fill and conventional resin composites and determine the pH and titratable acidity of mouthwashes. METHODS: Four hundred eighty specimens were fabricated in cylindrical moulds (10 mm in diameter and 2 mm in thickness). Before immersion, baseline data of surface hardness, roughness, and colour values were recorded. Each product of specimens (Filtek Z350XT, Premise, Filtek One Bulk Fill Restorative, SonicFil 2) were divided into 4 groups for 0.2% povidone iodine, 1% hydrogen peroxide, 0.12% chlorhexidine, and deionised water (serving as a control). The specimens were immersed in mouthwashes for 1 minute and then stored in artificial saliva until 24 hours. This process was repeated for 14 days. After immersion, surface hardness, roughness, and colour values of specimens were measured at 7 and 14 days. The data were statistically analysed by 2-way repeated analysis of variance, Tukey honestly significant difference, and t test (P < .05). RESULTS: After immersion, all mouthwashes caused significantly lower surface hardness and greater roughness and colour values (P < .05) on all resin composites tested. CONCLUSIONS: Mouthwashes had an effect on all resin composites evaluated leading to a significant decreased surface hardness and an increased roughness and colour values (P < .05).

17.
Acta Med Indones ; 54(3): 444-450, 2022 Jul.
Article in English | MEDLINE | ID: covidwho-2047003

ABSTRACT

Mortality rate among maintenance hemodialysis (HD) patients with COVID-19 is alarmingly high. In Fatmawati General Hospital, most of HD patients with COVID-19 presented with acute respiratory distress syndrome (ARDS). Hemoperfusion (HP) is a blood purification therapy used to remove cytokines and inflammatory mediators to prevent ARDS worsening and organ failure. We report 6 cases of COVID-19 in maintenance HD patients. HP and HD were performed in two consecutive days when patient developed early ARDS as indicated by inflammatory markers elevation. HP and HD were conducted by using resin-containing cartridge and high-flux dialyzer, respectively, for 4 hours. Improvements in CRP levels, PaO2/FiO2 ratios, and chest X-rays were observed after 2 sessions of HP in most of our patients. Based on our clinical experience, the timing of HP delivery is critical and should be undertaken in the early phase of ARDS, but larger studies are still needed.


Subject(s)
COVID-19 , Hemoperfusion , Respiratory Distress Syndrome , COVID-19/complications , COVID-19/therapy , Cytokines , Humans , Inflammation Mediators , Renal Dialysis , Respiratory Distress Syndrome/etiology , Respiratory Distress Syndrome/therapy
18.
Bangladesh Journal of Medical Science ; 21(4):676-684, 2022.
Article in English | EMBASE | ID: covidwho-2043413

ABSTRACT

Background: Impacts of primary oncology surgical procedure can impede restoration objectives. Restoring oral function, comfort and aesthetics is a challenge due to limitations in the restorative treatment options. Methodology: Literature review on the responsibilities, role of maxillofacial prosthodontist, materails and retentive aids used for prosthesis, classification of maxillofacial prostheses, recent advancements in MFP and Workflow for the fabrication of obturator prostheses in the COVID-19 pandemic scenario. Case report on the fabrication of Holllow bulb definitive obturator during pandemic crisis. A 47 years old male patient reported for post-surgical evaluation in maxillary posterior region of oral cavity. The patient had partial maxillectomysurgical procedure of squamous cell carcinoma in the palate 5 years back. To replace the gap created, the patient was using interim obturator. He had facial asymmetry and collapse. Prosthodontic rehabilitation with one piece closed hollow bulb obturator was planned & subsequently fabricated for the patient. For our case considering the feasibility & ease of manipulation, heat activated acrylic resin was used for this particular patient for rehabilitation. The method described is easy, simple, time saving & economical. Bulb portion was hollow & made of heat cure resin, so weight was less & less chances of tissue irritation. Results: With the Covid-19 infection protocol measures taken definitive obturator was given to the maxillectomy patient to restore aesthetics, function and comfort as well. After insertion of prostheses mastication, deglutition and phonetics were improved. Breathing problems were resolved and aesthetics was improved. Conclusion: A simplified technical approach for the treatment of a patient with palatal defect of and other supportive structure has been presented in Covid-19 situation following the described infection prevention protocols. The technique presented offers a method of obtaining a detailed impression of the defect and promptly provides the patient with a light weight, easyto-use and flexible tissue-tolerant obturator.

19.
Catalysts ; 12(8):829, 2022.
Article in English | ProQuest Central | ID: covidwho-2023197

ABSTRACT

The transmission of pathogens via surfaces poses a major health problem, particularly in hospital environments. Antimicrobial surfaces can interrupt the path of spread, while photocatalytically active titanium dioxide (TiO2) nanoparticles have emerged as an additive for creating antimicrobial materials. Irradiation of such particles with ultraviolet (UV) light leads to the formation of reactive oxygen species that can inactivate bacteria. The aim of this research was to incorporate TiO2 nanoparticles into a cellulose-reinforced melamine-formaldehyde resin (MF) to obtain a photocatalytic antimicrobial thermoset, to be used, for example, for device enclosures or tableware. To this end, composites of MF with 5, 10, 15, and 20 wt% TiO2 were produced by ultrasonication and hot pressing. The incorporation of TiO2 resulted in a small decrease in tensile strength and little to no decrease in Shore D hardness, but a statistically significant decrease in the water contact angle. After 48 h of UV irradiation, a statistically significant decrease in tensile strength for samples with 0 and 10 wt% TiO2 was measured but with no statistically significant differences in Shore D hardness, although a statistically significant increase in surface hydrophilicity was measured. Accelerated methylene blue (MB) degradation was measured during a further 2.5 h of UV irradiation and MB concentrations of 12% or less could be achieved. Samples containing 0, 10, and 20 wt% TiO2 were investigated for long-term UV stability and antimicrobial activity. Fourier-transform infrared spectroscopy revealed no changes in the chemical structure of the polymer, due to the incorporation of TiO2, but changes were detected after 500 h of irradiation, indicating material degradation. Specimens pre-irradiated with UV for 48 h showed a total reduction in Escherichia coli when exposed to UV irradiation.

20.
Nanomaterials (Basel) ; 12(17)2022 Sep 02.
Article in English | MEDLINE | ID: covidwho-2023952

ABSTRACT

A new method has been developed to impart the antimicrobial activity of silver nanoparticles to resin substrates. A resin substrate immersed in an aqueous solution of silver nitrate was irradiated with gamma ray or high energy electron beams. Silver nanoparticles were successfully immobilized on the resin surface directly by chemical reactions induced by ionizing radiation. It was experimentally confirmed that various resin materials, such as acrylonitrile-butadiene-styrene, polyethylene, polypropylene, polyvinyl chloride, and polycarbonate, were applicable for this process. The effects of gamma ray or electron beam irradiation on resin substrates were almost negligible since the irradiation dose was equal or less than that used for sterilization. Despite the small amount of Ag loadings, the obtained samples showed high antibacterial and antiviral activities.

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