Nanozymes based on octahedral platinum nanocrystals with {111} surface facets: glucose oxidase mimicking activity in electrochemical sensors

The ability of shape-controlled octahedral Pt nanoparticles to act as nanozyme mimicking glucose oxidase enzyme is reported. Extended {111} particle surface facets coupled with a size comparable to natural enzymes and easy-to-remove citrate coating give high affinity for glucose, comparable to the enzyme as proven by the steady-state kinetics of glucose electrooxidation. The easy and thorough removal of the citrate coating, demonstrated by X-ray photoelectron spectroscopy analysis, allows a highly stable deposition of the nanozymes on the electrode. The glucose electrochemical detection (at -0.2 V vs SCE) shows a linear response between 0.36 and 17 mM with a limit of detection of 110 mu M. A good reproducibility has been achieved, with an average relative standard deviation (RSD) value of 9.1% (n = 3). Similarly, a low intra-sensor variability has been observed, with a RSD of 6.6% (n = 3). Moreover, the sensor shows a long-term stability with reproducible performances for at least 2 months (RSD: 7.8%). Tests in saliva samples show the applicability of Pt nanozymes to commercial systems for non-invasive monitoring of hyperglycemia in saliva, with recoveries ranging from 92 to 98%

Virus de la Hepatitis E en Mendoza : presentación de 3 casos

La Hepatitis "E" es una enfermedad de distribución global, con morbilidad y mortalidad significativa, cuya incidencia ha aumentado en los últimos años. Con el propósito de potenciar la sospecha diagnostica de esta patología, se realiza una reactualización a partir de la presentación de 3 casos ocurridos en el Hospital Lagomaggiore de la Ciudad de Mendoza, Argentina.Hepatitis "E" is a disease of global distribution, with significantly morbidity and mortality, whose incidence keep growing as time goes by. In order to increase diagnostic suspicion of this illness, we perform a review based in three cases that take place in Lagomaggiore´s Hospital in Mendoza city, Argentina. Key words: Hepatitis, HEV.Fil: Miranda, Jimena. Hospital Luis Lagomaggiore (Mendoza, Argentina). Servicio de Clínica MédicaFil: Gisbert, Patricia. Hospital Luis Lagomaggiore (Mendoza, Argentina). Servicio de Clínica MédicaFil: Mastronardi, Valentina. Hospital Luis Lagomaggiore (Mendoza, Argentina). Servicio de Clínica MédicaFil: Clausen Karzovnik, Gabriela. Hospital Luis Lagomaggiore (Mendoza, Argentina). Servicio de Clínica MédicaFil: Lascano, Soledad. Hospital Luis Lagomaggiore (Mendoza, Argentina). Servicio de Clínica MédicaFil: Valli, Diego. Hospital Luis Lagomaggiore (Mendoza, Argentina). Servicio de Clínica MédicaFil: Salomón, Susana Elsa. Universidad Nacional de Cuyo. Facultad de Ciencias MédicasFil: Carena, José Alberto. Universidad Nacional de Cuyo. Facultad de Ciencias Médica

Infected pancreatic necrosis: outcomes and clinical predictors of mortality. A post hoc analysis of the MANCTRA-1 international study

: The identification of high-risk patients in the early stages of infected pancreatic necrosis (IPN) is critical, because it could help the clinicians to adopt more effective management strategies. We conducted a post hoc analysis of the MANCTRA-1 international study to assess the association between clinical risk factors and mortality among adult patients with IPN. Univariable and multivariable logistic regression models were used to identify prognostic factors of mortality. We identified 247 consecutive patients with IPN hospitalised between January 2019 and December 2020. History of uncontrolled arterial hypertension (p = 0.032; 95% CI 1.135-15.882; aOR 4.245), qSOFA (p = 0.005; 95% CI 1.359-5.879; aOR 2.828), renal failure (p = 0.022; 95% CI 1.138-5.442; aOR 2.489), and haemodynamic failure (p = 0.018; 95% CI 1.184-5.978; aOR 2.661), were identified as independent predictors of mortality in IPN patients. Cholangitis (p = 0.003; 95% CI 1.598-9.930; aOR 3.983), abdominal compartment syndrome (p = 0.032; 95% CI 1.090-6.967; aOR 2.735), and gastrointestinal/intra-abdominal bleeding (p = 0.009; 95% CI 1.286-5.712; aOR 2.710) were independently associated with the risk of mortality. Upfront open surgical necrosectomy was strongly associated with the risk of mortality (p < 0.001; 95% CI 1.912-7.442; aOR 3.772), whereas endoscopic drainage of pancreatic necrosis (p = 0.018; 95% CI 0.138-0.834; aOR 0.339) and enteral nutrition (p = 0.003; 95% CI 0.143-0.716; aOR 0.320) were found as protective factors. Organ failure, acute cholangitis, and upfront open surgical necrosectomy were the most significant predictors of mortality. Our study confirmed that, even in a subgroup of particularly ill patients such as those with IPN, upfront open surgery should be avoided as much as possible. Study protocol registered in ClinicalTrials.Gov (I.D. Number NCT04747990)

Size- and shape-controlled platinum and palladium nanoparticles for catalytic and biomedical applications

The aim of this doctoral project has been centered on the development of innovative green synthetic methods able to govern the key physico-chemical properties of noble metal nanoparticles (NPs). To fully uncover the potential of metallic NPs, it is necessary to finely control the shape of nanomaterials while keeping the ultra-small characteristics, in order to achieve superior efficiency (per mass unit), selectivity and enhanced activity in catalytic processes. Size and shape of the nanomaterial together with the capping agents govern the surface properties and all the processes happening at the surface, such as catalysis. Different shapes offer great versatility to tune the nanocrystal (NCs) catalytic properties, which are dictated by surface facets. Green synthetic procedures have been developed to obtain pure, monodisperse, citrate-capped Pt and Pd NPs with accurate control on their size and the shape, without the use of polymers, surfactants and organic solvents. For Pd NPs, different geometrical shapes were achieved, such as icosahedrons, cubes, rods and wires while maintaining the thickness of 7 nm and length ranging from 38 to 470 nm (in the case of rods and wires) and the size (in the case of cubes and icosahedron) below 10 nm. These engineered nanomaterials exhibited good biocompatibility along with interesting enzymatic and catalytic properties, due to the absence of sticky molecules, high quality of the surface and the removal of toxic reagents. Moreover, a green synthetic procedure has been developed to obtain ultra-small Pt NCs by combining a strong and a weak reducing agent in aqueous environment in a single reaction vessel in only 10 minutes. NCs with size as low as 2.8 nm and high percentage of {111} surface domains have been achieved. These NCs have been physico-chemically and electrochemically characterized, disclosing significant perspectives for their use as innovative electrocatalysts or nanozymes in portable diagnostics

From a Chemotherapeutic Drug to a High-Performance Nanocatalyst: A Fast Colorimetric Test for Cisplatin Detection at ppb Level

A rapid point-of-care method for the colorimetric detection of cisplatin was developed, exploiting the efficient conversion of the chemotherapeutic drug into a high-performance nanocatalyst with peroxidase enzyme mimics. This assay provides high specificity and ppb-detection sensitivity with the naked eye or a smartphone-based readout, outperforming many standard laboratorybased techniques. The nanocatalyst-enabled colorimetric assay can be integrated with machinelearning methods, providing accurate quantitative measurements. Such a combined approach opens interesting perspectives for the on-site monitoring of both chemotherapeutic patients to achieve optimal treatments and healthcare workers to prevent their unsafe exposure

From a Chemotherapeutic Drug to a High-Performance Nanocatalyst: A Fast Colorimetric Test for Cisplatin Detection at ppb Level

A rapid point-of-care method for the colorimetric detection of cisplatin was developed, exploiting the efficient conversion of the chemotherapeutic drug into a high-performance nanocatalyst with peroxidase enzyme mimics. This assay provides high specificity and ppb-detection sensitivity with the naked eye or a smartphone-based readout, outperforming many standard laboratory-based techniques. The nanocatalyst-enabled colorimetric assay can be integrated with machine-learning methods, providing accurate quantitative measurements. Such a combined approach opens interesting perspectives for the on-site monitoring of both chemotherapeutic patients to achieve optimal treatments and healthcare workers to prevent their unsafe exposure

Random Weights Neural Network for Low-Cost Readout of Colorimetric Reactions: Accurate Detection of Antioxidant Levels

The introduction of Point Of Care (POC) devices is revolutionizing the field of diagnostics, thanks to their ease of use, portability, and real-time results. However, despite such advantages, POCs are still less accurate than traditional laboratory-based methods. In most cases, this is due to the qualitative on-off response of POCs along with readout procedures involving methods that are easily influenced by the environmental conditions or by the acquisition step of the result. Automation of the readout using machine learning supported by frugal devices and lowcost sensing systems can significantly enhance the quality of the analysis performed by POC devices, while maintaining the aforementioned advantages. This paper proposes the use of random-based neural networks to accurately assess the salivary antioxidant level detected through a colorimetric reaction. As a test case, a low-cost IoT device equipped with a trained neural network that infers the antioxidant level in the user’s saliva was designed and tested. The experiments performed on real-world data confirm that the proposed solution outperforms the previously proposed readout strategy

Platinum Nanozymes Counteract Photoreceptor Degeneration and Retina Inflammation in a Light-Damage Model of Age-Related Macular Degeneration

: Degeneration of photoreceptors in age-related macular degeneration (AMD) is associated with oxidative stress due to the intense aerobic metabolism of rods and cones that if not properly counterbalanced by endogenous antioxidant mechanisms can precipitate photoreceptor degeneration. In spite of being a priority eye disease for its high incidence in the elderly, no effective treatments for AMD exist. While systemic administration of antioxidants has been unsuccessful in slowing down degeneration, locally administered rare-earth nanoparticles were shown to be effective in preventing retinal photo-oxidative damage. However, because of inherent problems of dispersion in biological media, limited antioxidant power, and short lifetimes, these NPs are still confined to the preclinical stage. Here we propose platinum nanoparticles (PtNPs), potent antioxidant nanozymes, as a therapeutic tool for AMD. PtNPs exhibit high catalytic activity at minimal concentrations and protect primary neurons against oxidative insults and the ensuing apoptosis. We tested the efficacy of intravitreally injected PtNPs in preventing or mitigating light damage produced in dark-reared albino Sprague-Dawley rats by in vivo electroretinography (ERG) and ex vivo retina morphology and electrophysiology. We found that both preventive and postlesional treatments with PtNPs increased the amplitude of ERG responses to light stimuli. Ex vivo recordings demonstrated the selective preservation of ON retinal ganglion cell responses to light stimulation in lesioned retinas treated with PtNPs. PtNPs administered after light damage significantly preserved the number of photoreceptors and inhibited the inflammatory response to degeneration, while the preventive treatment had a milder effect. The data indicate that PtNPs can effectively break the vicious cycle linking oxidative stress, degeneration, and inflammation by exerting antioxidant and anti-inflammatory actions. The increased photoreceptor survival and visual performances in degenerated retinas, together with their high biocompatibility, make PtNPs a potential strategy to cure AMD

Ultrasmall, Coating-Free, Pyramidal Platinum Nanoparticles for High Stability Fuel Cell Oxygen Reduction

Ultrasmall (<5 nm diameter) noble metal nanoparticles with a high fraction of {111} surface domains are of fundamental and practical interest as electrocatalysts, especially in fuel cells; the nanomaterial surface structure dictates its catalytic properties, including kinetics and stability. However, the synthesis of size-controlled, pure Pt-shaped nanocatalysts has remained a formidable chemical challenge. There is an urgent need for an industrially scalable method for their production. Here, a one-step approach is presented for the preparation of single-crystal pyramidal nanocatalysts with a high fraction of {111} surface domains and a diameter below 4 nm. This is achieved by harnessing the shape-directing effect of citrate molecules, together with the strict control of oxidative etching while avoiding polymers, surfactants, and organic solvents. These catalysts exhibit significantly enhanced durability while, providing equivalent current and power densities to highly optimized commercial Pt/C catalysts at the beginning of life (BOL). This is even the case when they are tested in full polymer electrolyte membrane fuel cells (PEMFCs), as opposed to rotating disk experiments that artificially enhance electrode kinetics and minimize degradation. This demonstrates that the {111} surface domains in pyramidal Pt nanoparticles (as opposed to spherical Pt nanoparticles) can improve aggregation/corrosion resistance in realistic fuel cell conditions, leading to a significant improvement in membrane electrode assembly (MEA) stability and lifetime