Green synthesis trends and potential applications of bimetallic nanoparticles towards the sustainable development goals 2030.

The world faces threats that the United Nations has classified into 17 categories with different objectives as solutions for each challenge that are enclosed in the Sustainable Development Goals (SDGs). These actions involved the widespread use of science and technology as pathways to ensure their implementation. In this regard, sustainability science seeks the research community's contribution to addressing sustainable development challenges. Specifically, nanotechnology has been recognized as a key tool to provide disruptive and effective strategies to reach the SDGs. This review proposes the application of bimetallic nanoparticle substances capable of providing possible solutions to achieve target SDG 3: good health and well-being, SDG 6: clean water and sanitation, and SDG 12: responsible consumption and production. Furthermore, the term green nanotechnology is introduced in each section to exemplify how green synthesized bimetallic nanoparticles have been used to resolve each target SDG. This review also outlines the current scenario regarding the utilization of metallic nanomaterials in the market, together with the upscaling challenges and the lack of understanding of the long-term effects and hazards to the environment regarding bimetallic nanoparticles.

On the Significance of the ADNT1 Carrier in Arabidopsis thaliana under Waterlogging Conditions.

Among the adenylate carriers identified in Arabidopsis thaliana, only the AMP/ATP transporter ADNT1 shows increased expression in roots under waterlogging stress conditions. Here, we investigated the impact of a reduced expression of ADNT1 in A. thaliana plants submitted to waterlogging conditions. For this purpose, an adnt1 T-DNA mutant and two ADNT1 antisense lines were evaluated. Following waterlogging, ADNT1 deficiency resulted in a reduced maximum quantum yield of PSII electron transport (significantly for adnt1 and antisense Line 10), indicating a higher impact caused by the stress in the mutants. In addition, ADNT1 deficient lines showed higher levels of AMP in roots under nonstress condition. This result indicates that the downregulation of ADNT1 impacts the levels of adenylates. ADNT1-deficient plants exhibited a differential expression pattern of hypoxia-related genes with an increase in non-fermenting-related-kinase 1 (SnRK1) expression and upregulation of adenylate kinase (ADK) under stress and non-stress conditions. Together, these results indicated that the lower expression of ADNT1 is associated with an early "hypoxic status" due to the perturbation of the adenylate pool caused by reduced AMP import by mitochondria. This perturbation, which is sensed by SnRK1, results in a metabolic reprogramming associated with early induction of the fermentative pathway in ADNT1 deficient plants.

Diagnostic Accuracy of a Bacterial and Viral Biomarker Point-of-Care Test in the Outpatient Setting.

Importance: Acute respiratory infections (ARIs) account for most outpatient visits. Discriminating bacterial vs viral etiology is a diagnostic challenge with therapeutic implications. Objective: To investigate whether FebriDx, a rapid, point-of-care immunoassay, can differentiate bacterial- from viral-associated host immune response in ARI through measurement of myxovirus resistance protein A (MxA) and C-reactive protein (CRP) from finger-stick blood. Design, Setting, and Participants: This diagnostic study enrolled adults and children who were symptomatic for ARI and individuals in a control group who were asymptomatic between October 2019 and April 2021. Included participants were a convenience sample of patients in outpatient settings (ie, emergency department, urgent care, and primary care) who were symptomatic, aged 1 year or older, and had suspected ARI and fever within 72 hours. Individuals with immunocompromised state and recent vaccine, antibiotics, stroke, surgery, major burn, or myocardial infarction were excluded. Of 1685 individuals assessed for eligibility, 259 individuals declined participation, 718 individuals were excluded, and 708 individuals were enrolled (520 patients with ARI, 170 patients without ARI, and 18 individuals who dropped out). Exposures: Bacterial and viral immunoassay testing was performed using finger-stick blood. Results were read at 10 minutes, and treating clinicians and adjudicators were blinded to results. Main Outcomes and Measures: Bacterial- or viral-associated systemic host response to an ARI as determined by a predefined comparator algorithm with adjudication classified infection etiology. Results: Among 520 participants with ARI (230 male patients [44.2%] and 290 female patients [55.8%]; mean [SD] age, 35.3 [17.7] years), 24 participants with missing laboratory information were classified as unknown (4.6%). Among 496 participants with a final diagnosis, 73 individuals (14.7%) were classified as having a bacterial-associated response, 296 individuals (59.7%) as having a viral-associated response, and 127 individuals (25.6%) as negative by the reference standard. The bacterial and viral test correctly classified 68 of 73 bacterial infections, demonstrating a sensitivity of 93.2% (95% CI, 84.9%-97.0%), specificity of 374 of 423 participants (88.4% [95% CI, 85.0%-91.1%]), positive predictive value (PPV) of 68 of 117 participants (58.1% [95% CI, 49.1%-66.7%), and negative predictive value (NPV) of 374 of 379 participants (98.7% [95% CI, 96.9%-99.4%]).The test correctly classified 208 of 296 viral infections, for a sensitivity of 70.3% (95% CI, 64.8%-75.2%), a specificity of 176 of 200 participants (88.0% [95% CI, 82.8%-91.8%]), a PPV of 208 of 232 participants (89.7% [95% CI, 85.1%-92.9%]), and an NPV of 176 of 264 participants (66.7% [95% CI, 60.8%-72.1%]). Conclusions and Relevance: In this study, a rapid diagnostic test demonstrated diagnostic performance that may inform clinicians when assessing for bacterial or viral etiology of ARI symptoms.

Avanzando en la sistematización del benchmarking en servicios de salud pública / Improving the systematization of benchmarking in public health services

La mejora continua de la gestión debería ser una aspiración para todas las organizaciones del sector público. Los elementos de comparación externa obenchmarkingidentifican buenas prácticas en organizaciones similares. En servicios de salud pública, obtener indicadores de este tipo no es fácil. Los objetivos de este trabajo son describir el proceso seguido para llevar a cabo un ejercicio debenchmarkingen una organización de salud pública, y compartir sus frutos. Para ello, se identificaron organizaciones para compararlas, y se buscaron en sus páginas web informes o memorias con indicadores de las actividades o resultados de los servicios de salud pública. Se identificaron limitaciones y condicionantes de los indicadores de las diferentes organizaciones, así como maneras de mejorar su capacidad de comparación. Finalmente, se propone un conjunto de 19 indicadores como núcleo inicial de comparación orientado a la gestión de calidad. (AU)

Continuous management improvement should be an aspiration for all public sector organizations. External comparison or benchmarking identifies good practices in similar organizations. For public health services, it is not easy to obtain such indicators. The objectives of this paper are to describe the process of conducting a benchmarking exercise for a public health agency, and to share its results. For this purpose, agencies that may be compared were identified, and their websites were searched for annual reports or other documents with indicators of the activities or results of public health services. Limitations and contextual aspects of the indicators of the different organizations were identified, as well as ways to improve their comparability. Finally, a set of 19 indicators is proposed, as an initial core for quality management comparisons. (AU)

Composition-Dependent Cytotoxic and Antibacterial Activity of Biopolymer-Capped Ag/Au Bimetallic Nanoparticles against Melanoma and Multidrug-Resistant Pathogens.

Nanostructured silver (Ag) and gold (Au) are widely known to be potent biocidal and cytotoxic agents as well as biocompatible nanomaterials. It has been recently reported that combining both metals in a specific chemical composition causes a significant enhancement in their antibacterial activity against antibiotic-resistant bacterial strains, as well as in their anticancer effects, while preserving cytocompatibility properties. In this work, Ag/Au bimetallic nanoparticles over a complete atomic chemical composition range were prepared at 10 at% through a green, highly reproducible, and simple approach using starch as a unique reducing and capping agent. The noble metal nanosystems were thoroughly characterized by different analytical techniques, including UV-visible and FT-IR spectroscopies, XRD, TEM/EDS, XPS and ICP-MS. Moreover, absorption spectra simulations for representative colloidal Ag/Au-NP samples were conducted using FDTD modelling. The antibacterial properties of the bimetallic nanoparticles were determined against multidrug-resistant Escherichia coli and methicillin-resistant Staphylococcus aureus, showing a clear dose-dependent inhibition even at the lowest concentration tested (5 µg/mL). Cytocompatibility assays showed a medium range of toxicity at low and intermediate concentrations (5 and 10 µg/mL), while triggering an anticancer behavior, even at the lowest concentration tested, in a process involving reactive oxygen species production per the nanoparticle Au:Ag ratio. In this manner, this study provides promising evidence that the presently fabricated Ag/Au-NPs should be further studied for a wide range of antibacterial and anticancer applications.

[Improving the systematization of benchmarking in public health services]. / Avanzando en la sistematización del benchmarking en servicios de salud pública.

Continuous management improvement should be an aspiration for all public sector organizations. External comparison or benchmarking identifies good practices in similar organizations. For public health services, it is not easy to obtain such indicators. The objectives of this paper are to describe the process of conducting a benchmarking exercise for a public health agency, and to share its results. For this purpose, agencies that may be compared were identified, and their websites were searched for annual reports or other documents with indicators of the activities or results of public health services. Limitations and contextual aspects of the indicators of the different organizations were identified, as well as ways to improve their comparability. Finally, a set of 19 indicators is proposed, as an initial core for quality management comparisons.

Pepper-Mediated Green Synthesis of Selenium and Tellurium Nanoparticles with Antibacterial and Anticancer Potential.

The production of nanoparticles for biomedical applications (namely with antimicrobial and anticancer properties) has been significantly hampered using traditional physicochemical approaches, which often produce nanostructures with poor biocompatibility properties requiring post-synthesis functionalization to implement features that such biomedical applications require. As an alternative, green nanotechnology and the synthesis of environmentally friendly nanomaterials have been gaining attention over the last few decades, using living organisms or biomolecules derived from them, as the main raw materials to produce cost-effective, environmentally friendly, and ready-to-be-used nanomaterials. In this article and building upon previous knowledge, we have designed and implemented the synthesis of selenium and tellurium nanoparticles using extracts from fresh jalapeño and habanero peppers. After characterization, in this study, the nanoparticles were tested for both their antimicrobial and anticancer features against isolates of antibiotic-resistant bacterial strains and skin cancer cell lines, respectively. The nanosystems produced nanoparticles via a fast, eco-friendly, and cost-effective method showing different antimicrobial profiles between elements. While selenium nanoparticles lacked an antimicrobial effect at the concentrations tested, those made of tellurium produced a significant antibacterial effect even at the lowest concentration tested. These effects were correlated when the nanoparticles were tested for their cytocompatibility and anticancer properties. While selenium nanoparticles were biocompatible and had a dose-dependent anticancer effect, tellurium-based nanoparticles lacked such biocompatibility while exerting a powerful anti-cancer effect. Further, this study demonstrated a suitable mechanism of action for killing bacteria and cancer cells involving reactive oxygen species (ROS) generation. In summary, this study introduces a new green nanomedicine synthesis approach to create novel selenium and tellurium nanoparticles with attractive properties for numerous biomedical applications.

Green synthesis and characterization of gold-based anisotropic nanostructures using bimetallic nanoparticles as seeds.

Nanostructured noble metals are of great interest because of their tunable optical and electronic properties. However, the green synthesis of anisotropic nanostructures with a defined geometry by the systematic nanoassembly of particles into specific shape, size, and crystallographic facets still faces major challenges. The present work aimed to establish an environmentally friendly methodology for synthesizing gold-based anisotropic nanostructures using starch-capped bimetallic silver/gold nanoparticles as seeds and hydrogen peroxide as a reducing agent.

Reversal of SARS-CoV2-Induced Hypoxia by Nebulized Sodium Ibuprofenate in a Compassionate Use Program.

INTRODUCTION: Sodium ibuprofenate in hypertonic saline (NaIHS) administered directly to the lungs by nebulization and inhalation has antibacterial and anti-inflammatory effects, with the potential to deliver these benefits to hypoxic patients. We describe a compassionate use program that offered this therapy to hospitalized COVID-19 patients. METHODS: NaIHS (50 mg ibuprofen, tid) was provided in addition to standard of care (SOC) to hospitalized COVID-19 patients until oxygen saturation levels of > 94% were achieved on ambient air. Patients wore a containment hood to diminish aerosolization. Outcome data from participating patients treated at multiple hospitals in Argentina between April 4 and October 31, 2020, are summarized. Results were compared with a retrospective contemporaneous control (CC) group of hospitalized COVID-19 patients with SOC alone during the same time frame from a subset of participating hospitals from Córdoba and Buenos Aires. RESULTS: The evolution of 383 patients treated with SOC + NaIHS [56 on mechanical ventilation (MV) at baseline] and 195 CC (21 on MV at baseline) are summarized. At baseline, NaIHS-treated patients had basal oxygen saturation of 90.7 ± 0.2% (74.3% were on supplemental oxygen at baseline) and a basal respiratory rate of 22.7 ± 0.3 breath/min. In the CC group, basal oxygen saturation was 92.6 ± 0.4% (52.1% were on oxygen supplementation at baseline) and respiratory rate was 19.3 ± 0.3 breath/min. Despite greater pulmonary compromise at baseline in the NaIHS-treated group, the length of treatment (LOT) was 9.1 ± 0.2 gs with an average length of stay (ALOS) of 11.5 ± 0.3 days, in comparison with an ALOS of 13.3 ± 0.9 days in the CC group. In patients on MV who received NaIHS, the ALOS was lower than in the CC group. In both NaIHS-treated groups, a rapid reversal of deterioration in oxygenation and NEWS2 scores was observed acutely after initiation of NaIHS therapy. No serious adverse events were considered related to ibuprofen therapy. Mortality was lower in both NaIHS groups compared with CC groups. CONCLUSIONS: Treatment of COVID-19 pneumonitis with inhalational nebulized NaIHS was associated with rapid improvement in hypoxia and vital signs, with no serious adverse events attributed to therapy. Nebulized NaIHS s worthy of further study in randomized, placebo-controlled trials (ClinicalTrials.gov: NCT04382768).

Green synthesis of starch-capped Cu2O nanocubes and their application in the direct electrochemical detection of glucose.

Glucose determination is an essential procedure in different fields, used in clinical analysis for the prevention and monitoring of diabetes. In this work, modified carbon paste electrodes with Cu2O nanocubes (Cu2O NCs) were developed to test electrochemical glucose detection. The synthesis of the Cu2O NCs was achieved by a green method using starch as the capping agent, obtaining cubic-like morphologies and particle sizes from 227 to 123 nm with increasing amounts of the capping agent, as corroborated by electron microscopy analysis. Their crystalline structure and purity were determined by X-ray diffraction. The capability of starch as a capping agent was verified by Fourier-transform infrared spectroscopy, in which the presence of functional groups of this biopolymer in the Cu2O NCs were identified. The electrochemical response to glucose oxidation was determined by cyclic voltammetry, obtaining a linear response of the electrical current as a function of glucose concentration in the range 100-700 µM, with sensitivities from 85.6 to 238.8 µA mM-1 cm-2, depending on the amount of starch used in the synthesis of the Cu2O NCs.

Efficacy of tailored recommendations to promote healthy lifestyles: a post hoc analysis of a randomized controlled trial.

Prevention is the key to stopping the ravages of cardiovascular diseases, the main cause of death worldwide. The objective was to analyze the efficacy of tailored recommendations to promote healthy lifestyles. Parallel-arm randomized controlled trial with 1 year follow-up. Individuals aged 35-74 years from Girona (Spain) randomly selected from a population with no cardiovascular diseases at baseline were included. Participants in the intervention group received a brochure with tailored healthy choices according to the individual risk profile and a trained nurse explained all recommendations in detail in a 30 min consultation. One year changes in smoking, Mediterranean diet adherence, physical activity, and weight were analyzed with McNemar, Student's t, Wilcoxon, and Fisher exact tests according to an intention-to-treat strategy. Of 955 individuals (52.3% women; mean age 50 [±10] years) randomly allocated to the intervention or control group, one participant in each group presented a cardiovascular event and 768 (81%) were reexamined at 1 year follow-up. The prevalence of nonsmokers increased in both the intervention and control groups (78.1%-82.5%, p = <.001, and 76.7% to 78.8%, p = .015, respectively); however, significance persisted only in the intervention group when stratified by sex, age group, and educational level. Adherence to a Mediterranean diet increased in the intervention group (22.3%-26.5%, p = .048). In conclusion, a brief personalized intervention with science-based recommendations according to individual risk profiles appears to improve healthy lifestyles, particularly nonsmoking and adherence to a Mediterranean diet. This promising intervention system offers evidence-based recommendations to develop healthy lifestyles.

Aloe Vera-Mediated Te Nanostructures: Highly Potent Antibacterial Agents and Moderated Anticancer Effects.

Cancer and antimicrobial resistance to antibiotics are two of the most worrying healthcare concerns that humanity is facing nowadays. Some of the most promising solutions for these healthcare problems may come from nanomedicine. While the traditional synthesis of nanomaterials is often accompanied by drawbacks such as high cost or the production of toxic by-products, green nanotechnology has been presented as a suitable solution to overcome such challenges. In this work, an approach for the synthesis of tellurium (Te) nanostructures in aqueous media has been developed using aloe vera (AV) extracts as a unique reducing and capping agent. Te-based nanoparticles (AV-TeNPs), with sizes between 20 and 60 nm, were characterized in terms of physicochemical properties and tested for potential biomedical applications. A significant decay in bacterial growth after 24 h was achieved for both Methicillin-resistant Staphylococcus aureus and multidrug-resistant Escherichia coli at a relative low concentration of 5 µg/mL, while there was no cytotoxicity towards human dermal fibroblasts after 3 days of treatment. AV-TeNPs also showed anticancer properties up to 72 h within a range of concentrations between 5 and 100 µg/mL. Consequently, here, we present a novel and green approach to produce Te-based nanostructures with potential biomedical applications, especially for antibacterial and anticancer applications.

Green nanomedicine: the path to the next generation of nanomaterials for diagnosing brain tumors and therapeutics?

Introduction: Current brain cancer treatments, based on radiotherapy and chemotherapy, are sometimes successful, but they are not free of drawbacks.Areas covered: Traditional methods for the treatment of brain tumors are discussed here with new solutions presented, among which the application of nanotechnology has demonstrated promising results over the past decade. The traditional synthesis of nanostructures, which relies on the use of physicochemical methodologies are discussed, and their associated concerns in terms of environmental and health impact due to the production of toxic by-products, need for toxic catalysts, and their lack of biocompatibility are presented. An overview of the current situation for treating brain tumors using nanotechnological-based approaches is introduced, and some of the latest advances in the application of green nanomaterials (NMs) for the effective targeting of brain tumors are presented.Expert opinion: Green nanotechnology is introduced as a potential solution to toxic NMs through the application of environmentally friendly and cost-effective protocols using living organisms and biomolecules. The current status of this field, such as those involving clinical trials, is included, and the possible limitations of green-NMs and potential ways to avoid those limitations are discussed so that the field can potentially evolve.

Control of cardiovascular risk factors with tailored recommendations: A randomized controlled trial.

This study analyzed the efficacy of tailored recommendations to control cardiovascular risk factors at 1-year follow-up in a population-based randomized controlled trial in individuals aged 35-74 years with no history of cardiovascular disease at baseline. Total, low-density lipoprotein (LDL), and high-density lipoprotein cholesterol and systolic and diastolic blood pressure (BP) were measured at baseline and at 1-year follow-up. The primary outcome was the quantitative change in total cholesterol. To estimate the differences within and between groups, McNemar and Student t-tests were applied according to an intention-to-treat strategy. We enrolled 955 individuals [52.3% women; mean age, 50 years (standard deviation 10)]. Finally, 1 participant in each group presented a cardiovascular event and 768 were reexamined at 1-year follow-up. Intervention and control groups showed significant increases in total cholesterol [5.49 (standard deviation 1.02) to 5.56 (1.06) mmol/L and 5.34 (0.94) to 5.43 (0.93) mmol/L, respectively]. Men in the intervention group showed significant decreases in systolic and diastolic BP [117.2 (14.6) to 115.6 mmHg (14.1) and 77.9 (9.7) to 76.5 mmHg (9.7), respectively]; no changes were found in the rates of total cholesterol <5.2 mmol/L and LDL cholesterol <3.0 mmol/L. In the control group, both values were significantly decreased (43.5 to 36.4% and 26.4 to 20.8%, respectively) in men. In the stratified analysis, women showed no differences in any of the outcomes. In conclusion, an intervention with tailored recommendations increased mean total cholesterol values. The intervention effect was higher in men who maintained blood lipids at optimal levels and had decreased BP values.

Impact of COVID-19 outbreak by income: hitting hardest the most deprived.

BACKGROUND: The impact of the 2019 coronavirus disease (COVID-19) has many facets. This ecological study analysed age-standardized incidence rates by economic level in Barcelona. METHODS: We evaluated confirmed cases of COVID-19 in Barcelona (Spain) between 26 February 2020 and 19 April 2020. Districts were classified according to most recent (2017) mean income data. The reference for estimating age-standardized cumulative incidence rates was the 2018 European population. The association between incidence rate and mean income by district was estimated with the Spearman rho. RESULTS: The lower the mean income, the higher the COVID-19 incidence (Spearman rho = 0.83; P value = 0.003). Districts with the lowest mean income had the highest incidence of COVID-19 per 10 000 inhabitants; in contrast, those with the highest income had the lowest incidence. Specifically, the district with the lowest income had 2.5 times greater incidence of the disease, compared with the highest-income district [70 (95% confidence interval 66-73) versus 28 (25-31), respectively]. CONCLUSIONS: The incidence of COVID-19 showed an inverse socioeconomic gradient by mean income in the 10 districts of the city of Barcelona. Beyond healthcare for people with the disease, attention must focus on a health strategy for the whole population, particularly in the most deprived areas.

Citric Juice-mediated Synthesis of Tellurium Nanoparticles with Antimicrobial and Anticancer Properties.

Bacterial infections and cancer are two of the most significant concerns that the current healthcare system should tackle nowadays. Green nanotechnology is presented as a feasible solution that is able to produce materials with significant anticancer and antibacterial activity, while overcoming the main limitations of traditional synthesis. In the present work, orange, lemon and lime extracts were used as both reducing and capping agents for the green synthesis of tellurium nanoparticles (TeNPs) using a microwave-assisted reaction. TeNPs showed a uniform size distribution, and rod- and cubic-shapes, and were extensively characterized in terms of morphology, structure and composition using TEM, SEM, XPS, XRD, FTIR and EDX analysis. TeNPs showed an important antibacterial activity against both Gram-negative and -positive bacteria in a range concentrations from 5 to 50 µg/mL over a 24-hour time period. Besides, nanoparticles showed anticancer effect towards human melanoma cells over 48 hours at concentrations up to 50 µg/mL. Moreover, the Te nanostructures showed no significant cytotoxic effect towards human dermal fibroblast at concentrations up to 50 µg/mL. Therefore, we present an environmentally-friendly and cost-effective synthesis of TeNPs using only fruit juices and showing enhanced and desirable biomedical properties towards both infectious diseases and cancer.

Comparison of cytocompatibility and anticancer properties of traditional and green chemistry-synthesized tellurium nanowires.

BACKGROUND: Traditional physicochemical approaches for the synthesis of compounds, drugs, and nanostructures developed as potential solutions for antimicrobial resistance or against cancer treatment are, for the most part, facile and straightforward. Nevertheless, these approaches have several limitations, such as the use of toxic chemicals and production of toxic by-products with limited biocompatibility. Therefore, new methods are needed to address these limitations, and green chemistry offers a suitable and novel answer, with the safe and environmentally friendly design, manufacturing, and use of minimally toxic chemicals. Green chemistry approaches are especially useful for the generation of metallic nanoparticles or nanometric structures that can effectively and efficiently address health care concerns. OBJECTIVE: Here, tellurium (Te) nanowires were synthesized using a novel green chemistry approach, and their structures and cytocompatibility were evaluated. METHOD: An easy and straightforward hydrothermal method was employed, and the Te nanowires were characterized using transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy, and optical microscopy for morphology, size, and chemistry. Cytotoxicity tests were performed with human dermal fibroblasts and human melanoma cells (to assess anticancer properties). The results showed that a treatment with Te nanowires at concentrations between 5 and 100 µg/mL improved the proliferation of healthy cells and decreased cancerous cell growth over a 5-day period. Most importantly, the green chemistry -synthesized Te nanowires outperformed those produced by traditional synthetic chemical methods. CONCLUSION: This study suggests that green chemistry approaches for producing Te nanostructures may not only reduce adverse environmental effects resulting from traditional synthetic chemistry methods, but also be more effective in numerous health care applications.

Starch-mediated synthesis of mono- and bimetallic silver/gold nanoparticles as antimicrobial and anticancer agents.

BACKGROUND AND AIM: Bimetallic silver/gold nanosystems are expected to significantly improve therapeutic efficacy compared to their monometallic counterparts by maintaining the general biocompatibility of gold nanoparticles (AuNPs) while, at the same time, decreasing the relatively high toxicity of silver nanoparticles (AgNPs) toward healthy human cells. Thus, the aim of this research was to establish a highly reproducible one-pot green synthesis of colloidal AuNPs and bimetallic Ag/Au alloy nanoparticles (NPs; Ag/AuNPs) using starch as reducing and capping agent. METHODS: The optical properties, high reproducibility, stability and particle size distribution of the colloidal NPs were analyzed by ultraviolet (UV)-visible spectroscopy, dynamic light scattering (DLS) and ζ-potential. The presence of starch as capping agent was determined by Fourier transform infrared (FT-IR) spectroscopy. The structural properties were studied by X-ray diffraction (XRD). Transmission electron microscopy (TEM) imaging was done to determine the morphology and size of the nanostructures. The chemical composition of the nanomaterials was determined by energy-dispersive X-ray spectroscopy (EDS) and inductively coupled plasma mass spectrometry (ICP-MS) analysis. To further study the biomedical applications of the synthesized nanostructures, antibacterial studies against multidrug-resistant (MDR) Escherichia coli and methicillin-resistant Staphylococcus aureus (MRSA) were conducted. In addition, the NPs were added to the growth media of human dermal fibroblast (HDF) and human melanoma cells to show their cytocompatibility and cytotoxicity, respectively, over a 3-day experiment. RESULTS: UV-visible spectroscopy confirmed the highly reproducible green synthesis of colloidal AuNPs and Ag/AuNPs. The NPs showed a face-centered cubic crystal structure and an icosahedral shape with mean particle sizes of 28.5 and 9.7 nm for AuNPs and Ag/AuNPs, respectively. The antibacterial studies of the NPs against antibiotic-resistant bacterial strains presented a dose-dependent antimicrobial behavior. Furthermore, the NPs showed cytocompat-ibility towards HDF, but a dose-dependent anticancer effect was found when human melanoma cells were grown in presence of different NP concentrations for 72 hours. CONCLUSION: In this study, mono- and bimetallic NPs were synthesized for the first time using a highly reproducible, environmentally friendly, cost-effective and quick method and were successfully characterized and tested for several anti-infection and anticancer biomedical applications.

Synthesis of colloidal silver nanoparticle clusters and their application in ascorbic acid detection by SERS.

Ascorbic acid (vitamin C) has an essential role in the human body mainly due to its antioxidant function. In this work, metallic silver nanoparticle (AgNP) colloids were used in SERS experiments to detect ascorbic acid in aqueous solution. The AgNPs were synthesized by a green method using potato starch as reducing and stabilizing agent, and water as the solvent. The optical properties of the yellowish as-synthesized silver colloids were characterized by UV-vis spectroscopy, in which besides a typical band at 410 nm related to the localized surface plasmon resonance of the silver nanoparticles, a shoulder band around 500 nm, due to silver nanoparticle cluster formation, is presented when relatively higher concentrations of starch are used in the synthesis. These starch-capped silver nanoparticles show an intrinsic Raman peak at 1386 cm-1 assigned to deformation modes of the starch structure. The increase of the intensity of the SERS peak at 1386 cm-1 with an increase in the concentration of the ascorbic acid is related to a decrease of the gap between dimers and trimers of the silver nanoparticle clusters produced by the presence of ascorbic acid in the colloid. The limit of detection of this technique for ascorbic acid is 0.02 mM with a measurement concentration range of 0.02-10 mM, which is relevant for the application of this method for detecting ascorbic acid in biological specimen.

The frequency-dependent AC photoresistance behavior of ZnO thin films grown on different sapphire substrates.

Zinc oxide (ZnO) thin films were grown by pulsed layer deposition under an N2 atmosphere at low pressures on a- and r-plane sapphire substrates. Structural studies using X-ray diffraction confirmed that all films had a wurtzite phase. ZnO thin films on a- and r-plane sapphire have grown with orientations along the [0002] and [112[combining macron]0] directions, respectively. Room temperature photoluminescence measurements indicate that the presence of native point defects (interstitial zinc, oxygen vacancies, oxygen antisites and zinc vacancies) is more preponderant for ZnO thin films grown on the r-plane sapphire substrate than the sample grown on the a-plane sapphire substrate. Room temperature impedance spectroscopy measurements were performed in an alternating current frequency range from 40 to 105 Hz in the dark and under normal light. An unusual positive photoresistance effect is observed at frequencies above 100 kHz, which we suggest to be due to intrinsic defects present in the ZnO thin films. Furthermore, an analysis of the optical time response revealed that the film grown on the r-plane sapphire substrate responds faster (characteristic relaxation times for τ1, τ2 and τ3 of 0.05, 0.26 and 6.00 min, respectively) than the film grown on the a-plane sapphire substrate (characteristic relaxation times for τ1, τ2 and τ3 of 0.10, 0.73 and 4.02 min, respectively).