Presence and Causes of Sterilization Equipment Failures with Biological Indicators in Dental Offices in Mexico: A Longitudinal Cohort.

Background/Objectives: Sterilization in dental practice is crucial for infection prevention. The aim of this study was to identify the presence and causes of bacterial growth using biological indicators in dental sterilization equipment in San Luis Potosí, S.L.P., Mexico, with different consecutive measurements over a year. Methods: This longitudinal cohort, conducted from January 2022 to January 2024 in San Luis Potosí, Mexico, aimed to identify the presence and causes of bacterial growth in dental sterilization equipment using biological indicators. A total of 207 dental offices were approached, and 175 participated, providing data through questionnaires and monitoring sterilization cycles with BIs. The checks were bimonthly for one year, with a total of six checks. Results: (a) An 11% (n = 1188) incidence of bacterial growth was observed, with a higher percentage in dry heat equipment (13%). (b) Upon analyzing the six consecutive verifications over a year, no statistically significant differences were observed in the failures of the sterilization cycles when comparing the two pieces of equipment. (c) Error in temperature and time of the equipment (OR = 4.0, 95% CI = 1.6-3.9, p = 0.0001) was significantly associated with the presence of bacterial growth during the one-year period. Conclusions: Monitoring sterilization cycles and identifying the causes of bacterial growth with different consecutive verifications decreased the presence of bacterial growth (failures) during the one-year period.

Development and Validation of UPLC Tandem Mass Spectrometry Assay for Ceftibuten and Sulbactam in Human Plasma.

A sensitive and rapid ultra-performance liquid chromatography coupled with -tandem mass spectrometry (UPLC-MS/MS) method was developed and validated to determine ceftibuten (CTB) and sulbactam (SUL) in human plasma. An ACQUITY UPLC HSS T3 C18 (2.1 × 100 mm), 1.8 µm column with gradient elution of water (0.1% formic acid) and acetonitrile was used for separation at a flow rate of 0.2 mL/min. This method involves a simple sample preparation with acetonitrile. The calibration curves of CTB and SUL in plasma showed good linearity over the concentration range of 0.50-25 µg/mL and with a correlation coefficient (r2) >0.99. This method was validated in terms of selectivity, linearity, precision, accuracy and stability. High precision was obtained with coefficients of variation <15%. Excellent recovery in the range of 90-104% was achieved for CTB and SUL was 86-110%. The method has the potential utility to support pharmacometric modeling in clinical practice and biopharmaceutic studies.

Influence of feeding practices in the composition and functionality of infant gut microbiota and its relationship with health.

Establishing the infant's gut microbiota has long-term implications on health and immunity. Breastfeeding is recognized as the best practice of infant nutrition in comparison with formula feeding. We evaluated the effects of the primary feeding practices by analyzing the infant growth and the potential association with gut diseases. A cross-sectional and observational study was designed. This study included 55 mothers with infants, who were divided according to their feeding practices in breastfeeding (BF), formula feeding (FF), and combined breast and formula feeding (CF). Anthropometric measurements of the participants were recorded. Additionally, non-invasive fecal samples from the infants were collected to analyze the microbiota by sequencing, immunoglobulin A (IgA) concentration (ELISA), and volatile organic compounds (gas chromatography with an electronic nose). Results showed that the microbiota diversity in the BF group was the highest compared to the other two groups. The IgA levels in the BF group were twice as high as those in the FF group. Moreover, the child´s growth in the BF group showed the best infant development when the data were compared at birth to the recollection time, as noted by the correlation with a decreased concentration of toxic volatile organic compounds. Interestingly, the CF group showed a significant difference in health status when the data were compared with the FF group. We conclude that early health practices influence children's growth, which is relevant to further research about how those infants' health evolved.

Development and evaluation of ciprofloxacin local controlled release materials based on molecularly imprinted polymers.

The aim of this study was the molecular imprinting polymers (MIPs) assessment as a controlled release system of ciprofloxacin. The MIPs synthesis was performed by three different methods: emulsion, bulk, and co-precipitation. Lactic acid (LA) and methacrylic acid (MA) were used as functional monomers and ethylene glycol dimethacrylate as crosslinker. Also, nonimprinted polymers (NIPs) were synthesized. MIPs and NIPs were characterized by scanning electron microscopy, Fourier Transform Infrared Reflection, specific surface area, pore size, and release kinetics. Their efficiency against Staphylococcus aureus and Escherichia coli, and their cytotoxicity in dermal fibroblast cells were proven. Results show that MIPs are mesoporous materials with a pore size between 10 and 20 nm. A higher adsorption with the co-precipitation MIP with MA as a monomer was found. The release kinetics proved that a non-Fickian process occurred and that the co-precipitation MIP with LA presented the highest release rate (90.51 mg/L) in 8 h. The minimum inhibitory concentration was found between 0.031 and 0.016 mg/L for Staphylococcus aureus and between 0.004 and 0.031 mg/L for the Escherichia coli. No cytotoxicity in cellular cultures was found; also, cellular growth was favored. This study demonstrated that MIPs present promising properties for drug administration and their application in clinical practice.

Multispecies oral biofilm and identification of components as treatment target.

Endodontic infections involve a multispecies biofilm, making it difficult to choose an antimicrobial treatment. Characteristics such as the pathogens involved and number of microorganisms, nutrients, material surface to develop the biofilm, flow and oxygenation conditions are important for biofilm development using in vitro models. OBJECTIVE: To develop a standardized biofilm model, which replicates the main features (chemical, microbiological, and topographical) of an infected root canal tooth to detect components as treatment target. DESIGN: Clinical strains of Enterococcus faecalis, Candida albicans, and Actinomyces israelii were isolated, and a multispecies biofilm was developed using continuous laminar flow reactors under anaerobic conditions in human dental roots. The microbiological composition was determined by counting colony-forming units and scanning electron microscope micrographs. In addition, the chemical composition of the exopolymeric matrix was determined by vibrational Raman spectroscopy and liquid chromatography of biofilm supernatant treated with enzyme. RESULTS: E. faecalis turned out to be the main microorganism in mature biofilm, this was related to the presence of ß-galactosidase detected by vibrational Raman spectroscopy. After the enzymatic treatment of the extracellular polymeric substance, the presence of mannose and glucose was established. CONCLUSIONS: The present work contributes to better understanding of standard conditions to develop a multispecies biofilm in human dental roots, which could have an impact on the generation of new root canal disinfection techniques in endodontic pathologies.

Fluoroquinolone Analogs, SAR Analysis, and the Antimicrobial Evaluation of 7-Benzimidazol-1-yl-fluoroquinolone in In Vitro, In Silico, and In Vivo Models.

Structure-activity relationship (SAR) studies allow the evaluation of the relationship between structural chemical changes and biological activity. Fluoroquinolones have chemical characteristics that allow their structure to be modified and new analogs with different therapeutic properties to be generated. The objective of this research is to identify and select the C-7 heterocycle fluoroquinolone analog (FQH 1-5) with antibacterial activity similar to the reference fluoroquinolone through in vitro, in silico, and in vivo evaluations. First, SAR analysis was conducted on the FQH 1-5, using an in vitro antimicrobial sensibility model in order to select the best compound. Then, an in silico model mechanism of action analysis was carried out by molecular docking. The non-bacterial cell cytotoxicity was evaluated, and finally, the antimicrobial potential was determined by an in vivo model of topical infection in mice. The results showed antimicrobial differences between the FQH 1-5 and Gram-positive and Gram-negative bacteria, identifying the 7-benzimidazol-1-yl-fluoroquinolone (FQH-2) as the most active against S. aureus. Suggesting the same mechanism of action as the other fluoroquinolones; no cytotoxic effects on non-bacterial cells were found. FQH-2 was demonstrated to decrease the amount of bacteria in infected wound tissue.

Radiosterilized Pig Skin, Silver Nanoparticles and Skin Cells as an Integral Dressing Treatment for Burns: Development, Pre-Clinical and Clinical Pilot Study.

Radiosterilized pig skin (RPS) has been used as a dressing for burns since the 1980s. Its similarity to human skin in terms of the extracellular matrix (ECM) allows the attachment of mesenchymal stem cells, making it ideal as a scaffold to create cellularized constructs. The use of silver nanoparticles (AgNPs) has been proven to be an appropriate alternative to the use of antibiotics and a potential solution against multidrug-resistant bacteria. RPS can be impregnated with AgNPs to develop nanomaterials capable of preventing wound infections. The main goal of this study was to assess the use of RPS as a scaffold for autologous fibroblasts (Fb), keratinocytes (Kc), and mesenchymal stem cells (MSC) in the treatment of second-degree burns (SDB). Additionally, independent RPS samples were impregnated with AgNPs to enhance their properties and further develop an antibacterial dressing that was initially tested using a burn mouse model. This protocol was approved by the Research and Ethics Committee of the INRLGII (INR 20/19 AC). Transmission electron microscopy (TEM) and dynamic light scattering (DLS) analysis of the synthesized AgNPs showed an average size of 10 nm and rounded morphology. Minimum inhibitory concentrations (MIC) and Kirby-Bauer assays indicated that AgNPs (in solution at a concentration of 125 ppm) exhibit antimicrobial activity against the planktonic form of S. aureus isolated from burned patients; moreover, a log reduction of 1.74 ± 0.24 was achieved against biofilm formation. The nanomaterial developed with RPS impregnated with AgNPs solution at 125 ppm (RPS-AgNPs125) facilitated wound healing in a burn mouse model and enhanced extracellular matrix (ECM) deposition, as analyzed by Masson's staining in histological samples. No silver was detected by energy-dispersive X-ray spectroscopy (EDS) in the skin, and neither by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) in different organs of the mouse burn model. Calcein/ethidium homodimer (EthD-1), 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT), and scanning electron microscopy (SEM) analysis demonstrated that Fb, Kc, and MSC could attach to RPS with over 95% cell viability. Kc were capable of releasing FGF at 0.5 pg above control levels, as analyzed by ELISA assays. An autologous RPS-Fb-Kc construct was implanted in a patient with SDB and compared to an autologous skin graft. The patient recovery was assessed seven days post-implantation, and the patient was followed up at one, two, and three months after the implantation, exhibiting favorable recovery compared to the gold standard, as measured by the cutometer. In conclusion, RPS effectively can be used as a scaffold for the culture of Fb, Kc, and MSC, facilitating the development of a cellularized construct that enhances wound healing in burn patients.

A systematic review of the protein composition of whole saliva in subjects with healthy periodontium compared with chronic periodontitis.

CONTEXT: Periodontitis is a chronic multifactorial inflammatory disease linked to oral microbiota dysbiosis. This disease progresses to infection that stimulates a host immune/inflammatory response, with progressive destruction of the tooth-supporting structures. OBJECTIVE: This systematic review aims to present a robust critical evaluation of the evidence of salivary protein profiles for identifying oral diseases using proteomic approaches and summarize the use of these approaches to diagnose chronic periodontitis. DATA SOURCES: A systematic literature search was conducted from January 1st, 2010, to December 1st, 2022, based on PICO criteria following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and by searching the three databases Science Direct, Scopus, and Springer Link. STUDY SELECTION: According to the inclusion criteria, eight studies were identified to analyze the proteins identified by proteomics. RESULTS: The protein family S100 was identified as the most abundant in patients with chronic periodontitis. In this family, an increased abundance of S100A8 and S100A9 from individuals with the active disease was observed, which strongly relates to the inflammatory response. Moreover, the ratio S100A8/S100A9 and the metalloproteinase-8 in saliva could differentiate distinct periodontitis groups. The changes in protein profile after non-surgical periodontal therapy improved the health of the buccal area. The results of this systematic review identified a set of proteins that could be used as a complementary tool for periodontitis diagnosis using salivary proteins. CONCLUSION: Biomarkers in saliva can be used to monitor an early stage of periodontitis and the progression of the disease following therapy.

Use of a Cellulase from Trichoderma reesei as an Adjuvant for Enterococcus faecalis Biofilm Disruption in Combination with Antibiotics as an Alternative Treatment in Secondary Endodontic Infection.

Apical periodontitis is an inflammation leading to the injury and destruction of periradicular tissues. It is a sequence of events that starts from root canal infection, endodontic treatment, caries, or other dental interventions. Enterococcus faecalis is a ubiquitous oral pathogen that is challenging to eradicate because of biofilm formation during tooth infection. This study evaluated a hydrolase (CEL) from the fungus Trichoderma reesei combined with amoxicillin/clavulanic acid as a treatment against a clinical E. faecalis strain. Electron microscopy was used to visualize the structure modification of the extracellular polymeric substances. Biofilms were developed on human dental apices using standardized bioreactors to evaluate the antibiofilm activity of the treatment. Calcein and ethidium homodimer assays were used to evaluate the cytotoxic activity in human fibroblasts. In contrast, the human-derived monocytic cell line (THP-1) was used to evaluate the immunological response of CEL. In addition, the secretion of the pro-inflammatory cytokines IL-6 and TNF-α and the anti-inflammatory cytokine IL-10 were measured by ELISA. The results demonstrated that CEL did not induce the secretion of IL-6 and TNF-α when compared with lipopolysaccharide used as a positive control. Furthermore, the treatment combining CEL with amoxicillin/clavulanic acid showed excellent antibiofilm activity, with a 91.4% reduction in CFU on apical biofilms and a 97.6% reduction in the microcolonies. The results of this study could be used to develop a treatment to help eradicate persistent E. faecalis in apical periodontitis.

Evaluation of Two Active System Encapsulant Matrices with Quercetin and Bacillus clausii for Functional Foods.

Currently, demand for functional foods is increasing in the public interest in order to improve life expectations and general health. Food matrices containing probiotic microorganisms and active compounds encapsulated into carrier agents are essential in this context. Encapsulation via the lyophilisation method is widely used because oxidation reactions that affect physicochemical and nutritional food properties are usually avoided. Encapsulated functional ingredients, such as quercetin and Bacillus clausii, using two carrier agents' matrices-I [inulin (IN), lactose (L) and maltodextrin (MX)] and II [arabic (A), guar (G), and xanthan (X) gums)]-are presented in this work. A D-optimal procedure involving 59 experiments was designed to evaluate each matrix's yield, viability, and antioxidant activity (AA). Matrix I (33.3 IN:33.3 L:33.3 MX) and matrix II (33.3 A:33.3 G:33.3 X) exhibited the best yield; viability of 9.7 log10 CFU/g and 9.73 log10 CFU/g was found in matrix I (using a ratio of 33.3 IN:33.3 L:33.3 MX) and matrix II (50 G:50 X), respectively. Results for the antioxidant capacity of matrix I (100 IN:0 L:0M X) and matrix II (0 A:50 G:50 X) were 58.75 and 55.54 (DPPH* scavenging activity (10 µg/mL)), respectively. Synergy between matrices I and II with use of 100IN:0L:OMX and 0A:50G:50X resulted in 55.4 log10 CFU/g viability values; the antioxidant capacity was 9. 52 (DPPH* scavenging activity (10 µg/mL). The present work proposes use of a carrier agent mixture to produce a functional ingredient with antioxidant and probiotic properties that exceed the minimum viability, 6.0 log10 CFU/g, recommended by the FAO/WHO (2002) to be probiotic, and that contributes to the recommended daily quercetin intake of 10-16 mg/day or inulin intake of 10-20 g/day and dietary fibre intake of 25-38 g per day.

Development of Radiosterilized Porcine Skin Electrosprayed with Silver Nanoparticles Prevents Infections in Deep Burns.

Extensive burns represent a significant challenge in biomedicine due to the multiple systemic and localized complications resulting from the major skin barrier loss. The functionalization of xenografts with nanostructured antibacterial agents proposes a fast and accessible application to restore barrier function and prevent localized bacterial contamination. Based on this, the objective of this work was to functionalize a xenograft by electrospray deposition with silver nanoparticles (AgNPs) and to evaluate its antibiofilm and cytotoxic effects on human fibroblasts. Initially, AgNPs were synthesized by a green microwave route with sizes of 2.1, 6.8, and 12.2 nm and concentrations of 0.055, 0.167, and 0.500 M, respectively. The AgNPs showed a size relationship directly proportional to the concentration of AgNO3, with a spherical and homogeneous distribution determined by high-resolution transmission electron microscopy. The surface functionalization of radiosterilized porcine skin (RPS) via electrospray deposition with the three AgNP concentrations (0.055, 0.167, and 0.500 M) in the epidermis and the dermis showed a uniform distribution on both surfaces by energy-dispersive X-ray spectroscopy. The antibiofilm assays of clinical multidrug-resistant Pseudomonas aeruginosa showed significant effects at the concentrations of 0.167 and 0.500 M, with a log reduction of 1.3 and 2.6, respectively. Additionally, viability experiments with human dermal fibroblasts (HDF) exposed to AgNPs released from functionalized porcine skin showed favorable tolerance, with retention of viability more significant than 90% for concentrations of 0.05 and 0.167 M after 24 h exposure. Antibacterial activity combined with excellent biocompatibility makes this biomaterial a candidate for antibacterial protection by inhibiting bacterial biofilms in deep burns during early stages of development.

Association between subjects with newly Diagnosed rheumatoid arthritis and dental caries / Asociación entre sujetos con artritis reumatoide recientemente diagnosticada y caries dental

Abstract Alterations in saliva, temporomandibular joint disorders, dysphagia, Sjogrens syndrome, dental caries, periodontal disease, and tooth loss have been identified in patients with Rheumatoid Arthritis. The aims of this research were 1) to study the association between newly diagnosed rheumatoid arthritis and dental caries and 2) to identify most frequent teeth with caries in study groups. A descriptive pilot study was performed. A total of 620 participants were evaluated, 29 met the selection criteria. The subjects were divided into 2 groups: 13 subjects with newly diagnosed rheumatoid arthritis and 16 subjects without rheumatoid arthritis. Salivary parameters, DMFT index, care index, FS-T index and Treatment Needs Index were evaluated in all participants. The Fishers Exact test and Mann-Whitney U test we used to establish the differences between groups. Low mean in all salivary parameters and a high caries frequency were observed in subjects with newly diagnosed rheumatoid arthritis compared to a control group (p<0.01). The right maxillary second premolar (n=6, 46%, p=0.0100); right mandibular second premolar (n=7,54%, p=0.0462) and left mandibular second molar (n=10,77%, p=0.0001) were the most frequent teeth with caries. Early diagnosis and early treatment of rheumatoid arthritis can improve the prognosis in most of patients. The development of new public health policies and care based on the prevention are necessary to improve the quality of patients lives.

Resumen Alteraciones en la saliva, trastornos de la articulación temporomandibular, disfagia, síndrome de Sjogren, caries dental, enfermedad periodontal y pérdida de dientes son algunas patologías que se han identificado en pacientes con artritis reumatoide. Los objetivos de este estudio fueron (1) Asociar la artritis reumatoide recientemente diagnosticada con la caries dentales e (2) Identificar los dientes más frecuentes con caries en los grupos de estudio. Se realizó un estudio piloto descriptivo. 620 participantes fueron evaluados, 29 sujetos cumplieron con los criterios de selección. Los sujetos se dividieron en 2 grupos: 13 sujetos con artritis reumatoide recién diagnosticados y 16 sujetos sin artritis reumatoide. En todos los participantes se evaluaron parámetros salivales, el índice CPOD, el índice IC, el índice FS-T y el índice INT. La prueba exacta de Fisher y U de Mann-Whitney se utilizaron para establecer diferencias entre grupos. En los resultados se observó un bajo promedio de los parámetros salivales y una alta frecuencia de caries en sujetos con artritis reumatoide recién diagnosticados comparados con un grupo control (p<0.01). El segundo premolar superior derecho (n=6,46%, p=0,0100); el segundo premolar mandibular derecho (n=7,54%, p=0.0462) y el segundo molar mandibular izquierdo (n=10,77%, p=0.0001) fueron los dientes más frecuentes con caries dental. El diagnóstico y el tratamiento temprano de la artritis reumatoide pueden mejorar el pronóstico en la mayoría de los pacientes. El desarrollo de nuevas políticas de salud pública basadas en la prevención de la cavidad bucal son necesarias para mejorar la calidad de vida de los pacientes.

An Analysis COVID-19 in Mexico: a Prediction of Severity.

BACKGROUND: Coronavirus disease 2019 (COVID-19) causes a mild illness in most cases; forecasting COVID-19-associated mortality and the demand for hospital beds and ventilators are crucial for rationing countries' resources. OBJECTIVE: To evaluate factors associated with the severity of COVID-19 in Mexico and to develop and validate a score to predict severity in patients with COVID-19 infection in Mexico. DESIGN: Retrospective cohort. PARTICIPANTS: We included 1,435,316 patients with COVID-19 included before the first vaccine application in Mexico; 725,289 (50.5%) were men; patient's mean age (standard deviation (SD)) was 43.9 (16.9) years; 21.7% of patients were considered severe COVID-19 because they were hospitalized, died or both. MAIN MEASURES: We assessed demographic variables, smoking status, pregnancy, and comorbidities. Backward selection of variables was used to derive and validate a model to predict the severity of COVID-19. KEY RESULTS: We developed a logistic regression model with 14 main variables, splines, and interactions that may predict the probability of COVID-19 severity (area under the curve for the validation cohort = 82.4%). CONCLUSIONS: We developed a new model able to predict the severity of COVID-19 in Mexican patients. This model could be helpful in epidemiology and medical decisions.

Synthesis and Antimicrobial Evaluation of Amino Acid Naphthoquinone Derivatives as Potential Antibacterial Agents.

BACKGROUND: The synthesis and biological evaluation of 1,4-naphthoquinone derivatives are of great interest since these compounds exhibit strong antibacterial, antifungal, antimalarial, and anticancer activities. The electronic properties of naphthoquinones are usually modulated by attaching functional groups containing nitrogen, oxygen, and sulfur atoms, which tune their biological potency and selectivity. METHODS: A series of 13 amino acid 1,4-naphthoquinone derivatives was synthesized under assisted microwave and ultrasound conditions. The antibacterial activity of compounds was tested against American Type Culture Collection (ATCC): Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Enterococcus faecalis, as well as 2 multidrug resistant pathogens: E. coli and S. aureus from clinical isolated. Minimal inhibitory concentration (MIC) was determined using the broth microdilution method. RESULTS: MIC of derivatives 4-11, 14, and 16 showed antimicrobial activity against Gram-positive and Gram-negative bacteria. Antimicrobial activities of the compounds 4-8 and 14 were ≤MIC 24.7 µg mL-1 against all the reference strains; even more, compound 6 showed the most potent activity with an MIC of 3.9 µg mL-1 on S. aureus. On the clinical isolated, the compounds 7, 8, and 14 showed an MIC of 49.7 and 24.7 µg mL-1 against S. aureus and E. coli, respectively. About ADME properties and Osiris analysis, the compounds 4-16 presented high gastrointestinal absorption and good characteristics for oral bioavailability, and compound 14 was the less toxic. CONCLUSION: Amino acid 1,4-naphthoquinone derivatives showed good in vitro antibacterial activity against clinical strains, and modifications on C-3 with a chloride atom enhanced the efficiency against the same pathogens.

Effect of the Intake of a Traditional Mexican Beverage Fermented with Lactic Acid Bacteria on Academic Stress in Medical Students.

Dysbiosis of the gut microbiota has been associated with different illnesses and emotional disorders such as stress. Traditional fermented foods that are rich in probiotics suggest modulation of dysbiosis, which protects against stress-induced disorders. The academic stress was evaluated in medical students using the SISCO Inventory of Academic Stress before and after ingestion of an aguamiel-based beverage fermented with Lactobacillus plantarum, Lactobacillus paracasei and Lactobacillus brevis (n = 27) and a control group (n = 18). In addition, microbial phyla in feces were quantified by qPCR. The results showed that the consumption of 100 mL of a beverage fermented with lactic acid bacteria (3 × 108 cfu/mL) for 8 weeks significantly reduced academic stress (p = 0.001), while the control group (placebo intervention) had no significant changes in the perception of academic stress (p = 0.607). Significant change (p = 0.001) was shown in the scores for environmental demands, and physical and psychological factors. Consumption of the fermented beverage significantly increased the phyla Firmicutes and Bacteroidetes but not Gammaproteobacteria. No significant changes were found in the control group, except for a slight increase in the phylum Firmicutes. The intake of this fermented beverage suggest a modulation of gut microbiota and possible reduction in stress-related symptoms in university students, without changing their lifestyle or diet.

Atmospheric Corrosion, Antibacterial Properties, and Toxicity of Silver Nanoparticles Synthesized by Two Different Routes.

Silver nanoparticles (AgNPs) have been widely employed or incorporated into different materials in biological application, due to their antibacterial properties. Therefore, antimicrobial capacity and cytotoxicity have been highly studied. However, most of these reports do not consider the possible corrosion of the nanomaterials during their exposure to atmospheric conditions since AgNPs undergo a transformation when they come in contact with a particular environment. Derived from this, the functionality and properties of the nanoparticles could decrease noticeably. The most common silver corrosion process occurs by the interaction of AgNPs with sulfur species (H2S) present in the atmospheric air, forming a corrosion layer of silver sulfide around the AgNPs, thus inhibiting the release of the ions responsible for the antimicrobial activity. In this work, AgNPs were synthesized using two different methods: one of them was based on a plant extract (Brickellia cavanillesii), and the other one is the well-known method using sodium borohydride (NaBH4). Chemical stability, corrosion, antibacterial activity, and toxic activity were evaluated for both sets of prepared samples, before and after exposition to atmospheric air for three months. The structural characterization of the samples, in terms of crystallinity, chemical composition, and morphology, evidenced the formation of link structures with nanobridges of Ag2S for non- "green" AgNPs after the air exposition and the intact preservation of silver core for the "green" sample. The antibacterial activity showed a clear improvement in the antimicrobial properties of silver in relation to the "green" functionalization, particle size control, and size reduction, as well as the preservation of the properties after air exposition by the effective "green" protection. The cytotoxicity effect of the different AgNPs against mononuclear cells showed a notable increment in the cell viability by the "green" functionalization.

Characterization, antibiofilm and biocompatibility properties of chitosan hydrogels loaded with silver nanoparticles and ampicillin: an alternative protection to central venous catheters.

The purpose of this study was to generate novel chitosan hydrogels (CHs) loaded with silver nanoparticles (AgNPs) and ampicillin (AMP) to prevent early formation of biofilms. AgNPs and CHs were characterized by UV-Vis, DLS, TEM, rheology, FT-IR, Raman, and SEM. The antibiofilm effect of the formulations was investigated against four multidrug-resistant and extensively drug-resistant pathogens using a colony biofilm, a high cell density and gradients model. Also, their hemostatic properties and cytotoxic effect were evaluated. Rheology results showed that CHs with AgNPs and AMP are typical non-Newtonian pseudoplastic fluids. The CH with 25 ppm of AgNPs and 50 ppm AMP inhibited the formation of biofilms of Acinetobacter baumannii, Enterococcus faecium and Staphylococcus epidermidis, while a ten-fold increase of the antimicrobial's concentration was needed to inhibit the biofilm of the ß-lactamase positive Enterobacter cloacae. Further, CH with 250 ppm of AgNPs and 500 ppm AMP showed anticoagulant effect, and it was shown that all formulations were biocompatible. Besides to previous reports that described the bioadhesion properties of chitosan, these results suggest that AgNPs and AMP CHs loaded could be used as prophylactic treatment in patients with central venous catheter (CVC), inhibiting the formation of biofilms in their early stages, in addition to their anticoagulant effect and biocompatibility, those properties could keep the functionality of CVC helping to prevent complications such as sepsis and thrombosis.

Effective control of biofilms by photothermal therapy using a gold nanorod hydrogel.

Biofilms are matrices synthesized by bacteria containing polysaccharides, DNA, and proteins. The development of biofilms in infectious processes can induce a chronic inflammatory response that may progress to the destruction of tissues. The treatment of biofilms is difficult because they serve as a bacterial mechanism of defense and high doses of antibiotics are necessary to treat these infections with limited positive results. It has been demonstrated that photothermal therapy using gold nanorods (AuNRs) is an attractive treatment because of its anti-biofilm activity. The purpose of this work was to generate a novel chitosan-based hydrogel embedded with AuNRs to evaluate its anti-biofilm activity. AuNRs were synthesized by the seed-mediated growth method and mixed with the chitosan-based hydrogel. Hydrogels were characterized and tested against two bacterial strains by irradiating the produced biofilm in the presence of the nanoformulation with a laser adjusted at the near infrared spectrum. In addition, the safety of the nanoformulation was assessed with normal human gingival fibroblasts. Results showed that a significant bacterial killing was measured when biofilms were exposed to an increase of 10°C for a short time of 2 min. Moreover, no cytotoxicity was measured when normal gingival fibroblasts were exposed to the nanoformulation using the bactericidal conditions. The development of the reported formulation can be used as a direct application to treat periodontal diseases or biofilm-produced bacteria that colonize the oral cavity.

Antimicrobial Peptides-based Nanostructured Delivery Systems: An Approach for Leishmaniasis Treatment.

BACKGROUND: Leishmaniasis is a major health problem mainly in tropical and subtropical areas worldwide, although in the last decades it has been treated with the use of conventional drugs such as amphotericin, the emergence of multidrug-resistant strains has raised a warning signal to the public health systems thus a new call for the creation of new leishmanicidal drugs is needed. METHODS: The goal of this review was to explore the potential use of antimicrobial peptides-based nanostructured delivery systems as an approach for leishmaniasis treatment. RESULTS: Within these new potential drugs, human host defense peptides (HDP) can be included given their remarkable antimicrobial activity and their outstanding immunomodulatory functions for the therapy of leishmaniasis. CONCLUSION: Though several approaches have been done using these peptides, new ways for delivering HDPs need to be analyzed, such is the case for nanotechnology.

Evaluation of anti-biofilm and cytotoxic effect of a gel formulation with Pluronic F-127 and silver nanoparticles as a potential treatment for skin wounds.

The skin wounds cause serious burden to healthcare systems. The lack of sterility of the innate barrier function of the skin facilitates the development of microbial communities within the wound environment especially in biofilm form. Since biofilm is difficult to eradicate, new treatments have been established, such as silver nanoparticles (AgNPs), which antimicrobial and anti-biofilm properties have been studied, nevertheless, their toxic effects are known too. Different concentrations of AgNPs stabilized with a biocompatible and thermo-reversible vehicle as hydrogel Pluronic F-127 were synthesized, those formulations presented interesting thermo-reversibility which could be used to apply on wounds. The formulations (Gel 62.5, 125, and 250 ppm of AgNPs) proposed in this study showed in vitro a total inhibition of clinical strains (Staphylococcus aureus and Pseudomonas aeruginosa) in planktonic form, as well as, anti-biofilm activity was archived with the formulation of Gel 250 ppm, a total inhibition of biofilm formation with mixed culture was registered in the first 30 min of biofilm growth; even more, the viability of human fibroblasts with all gels formulations was >95%, in contrast to silver sulfadiazine cream 1% which showed the highest cytotoxic effect. PF-127 gel with AgNPs could be a prophylactic treatment for skin wounds, because its activity in critical steps on biofilm formation.