Laura Galicia

This work presents the development of a biosensing platform for hydrogen peroxide (H₂O₂) electrochemical reduction. The developed platform uses a multi-walled carbon nanotube paste (PMWCNT) and the enzyme cholesterol oxidase (ChOx). The supramolecular architecture of the PMWCNT/ChOx platform was characterized using cyclic voltammetry, electrochemical impedance spectroscopy, and amperometry. The results indicated that the presence of ChOx enhances the sensitivity of electrochemical detection for H₂O₂ by 21 times compared to that without ChOx. The designed electrochemical sensing bio-platform for H₂O₂ shows a sensitivity of 26.15 µA/mM in the linear range from 0.4 to 4.0 mM, an LOD of 0.43 µM, and an LOQ of 1.31 µM. Furthermore, in silico studies (molecular dynamics simulations, molecular docking assays, and binding free energy calculations (ΔG_b)) were carried out to characterize and validate the molecular interaction between ChOx and H₂O₂. The computed data confirmed that the binding is spontaneous, and the type of labile interaction promotes a rapid electrochemical reduction of H₂O₂.

An overview of the electrochemical sensors and biosensors developed at Universidad Autónoma Metropolitana Unidad Iztapalapa, is summarized by describing the principal contributions in the field performed by the Electrochemistry and Analytical Chemistry research areas of the Chemistry Department. Here, we divided the contributions into four main groups: fabrication and characterization of surfaces, electrochemical sensors and biosensors with environmental applications, electrochemical sensors and biosensors with applications in the food industry, and electrochemical sensors and biosensors with biomedical applications in the healthcare industry; the foundation of the Institution, the creation of the Electrochemistry and Analytical Chemistry research areas, and the first electrochemical sensor development at the institution are cited in the historical context of the scientific electrochemical sensors and biosensors timeline. Resumen. Una visión general de los sensores y biosensores electroquímicos desarrollados en la Universidad Autónoma Metropolitana Unidad Iztapalapa, se resume describiendo los principales aportes en el campo realizados por las áreas de investigación de Electroquímica y Química Analítica del Departamento de Química de esta institución. Hemos dividimos las contribuciones en cuatro grupos principales: fabricación y caracterización de superficies, sensores y biosensores electroquímicos con aplicaciones ambientales, sensores y biosensores electroquímicos con aplicaciones en la industria alimentaria, y sensores y biosensores electroquímicos con aplicaciones biomédicas en la industria para el cuidado de la salud; la creación de la Institución, las áreas de investigación de electroquímica y química analítica, así como el primer sensor electroquímico desarrollado en la Institución, se citan en el contexto histórico de la cronología científica de los sensores y biosensores electroquímicos en el mundo.

An electrochemical biosensor based on the immobilization of glucose oxidase into an electropolymerized p-coumaric acid membrane on a Pt electrode has been developed and evaluated for glucose detection in the range of 1 to 30 mM. The glucose biosensor exhibits a sensitivity of 36.96 mA/mMcm², a LOD of 0.66 mM, and a LOQ of 2.18 mM. The biosensing membrane was electropolymerized by cyclic voltammetry in 100 mM phosphates pH 7.00 and 3% ethanol containing glucose oxidase and p-coumaric acid. The glucose biosensors’ stability, repeatability, reproducibility, and selectivity were estimated. The biosensing membrane shows permselective properties and antifouling effects. The applicability of the developed glucose biosensor was evaluated in the presence of 20 mg/mL proteins, and any signal associated with biofouling was observed. The glucose biosensors were employed for the determination of the glucose concentration in three commercial beverages.

A biosensing membrane base on ferulic acid and glucose oxidase is synthesized onto a carbon paste electrode by electropolymerization via cyclic voltammetry in aqueous media at neutral pH at a single step. The developed biosensors exhibit a linear response from 0.082 to 34 mM glucose concentration, with a coefficient of determination R² equal to 0.997. The biosensors display a sensitivity of 1.1 μAmM⁻¹ cm⁻², a detection limit of 0.025 mM, and 0.082 mM as glucose quantification limit. The studies reveal stable, repeatable, and reproducible biosensors response. The results indicate that the novel poly-ferulic acid membrane synthesized by electropolymerization is a promising method for glucose oxidase immobilization towards the development of glucose biosensors. The developed glucose biosensors exhibit a broader linear glucose response than other polymer-based glucose biosensors.

The clinical presentation of COVID-19 is extremely heterogeneous, ranging from asymptomatic to severely ill patients. Thus, host genetic factors may be involved in determining disease presentation and progression. Given that carriers of single cystic fibrosis (CF)-causing variants of the CFTR gene—CF-carriers—are more susceptible to respiratory tract infections, our aim was to determine their likelihood of undergoing severe COVID-19. We implemented a cohort study of 874 individuals diagnosed with COVID-19, during the first pandemic wave in Italy. Whole exome sequencing was performed and validated CF-causing variants were identified. Forty subjects (16 females and 24 males) were found to be CF-carriers. Among mechanically ventilated patients, CF-carriers were more represented (8.7%) and they were significantly (p < 0.05) younger (mean age 51 years) compared to noncarriers (mean age 61.42 years). Furthermore, in the whole cohort, the age of male CF-carriers was lower, compared to noncarriers (p < 0.05). CF-carriers had a relative risk of presenting an abnormal inflammatory response (CRP ≥ 20 mg/dL) of 1.69 (p < 0.05) and their hazard ratio of death at day 14 was 3.10 (p < 0.05) in a multivariate regression model, adjusted for age, sex and comorbidities. In conclusion, CF-carriers are more susceptible to the severe form of COVID-19, showing also higher risk of 14-day death.

In this paper we report the highly sensitive quantification of 8-hydroxy 2'-deoxyguanosine (8-OHdG) or uric acid (UA) in the presence of ascorbic acid (AA) using glassy carbon electrodes (GCE) modified with multiple-wall carbon nanotubes (CNT), dispersed in various polymers such as nafion (GCE/CNT Pnaf),polyacrylic acid (GCE/CNT-Paa), percoll (GCE/CNT-Prl) and polyvinyl alcohol (GCE/CNT-Pva). The electrocatalytic activity of CNT deposited on GCE shows a significant diminish on the AA overpotential oxidation value (257 mV); making possible the AA oxidation process separation from 8-OHdG and UA ones. Using differential pulse anodic stripping voltammetry (DPASV), the analytes were quantified. The optimum sensitivity obtained in the quantification of 8-OHdG was (3.3 {plus minus} 0.1) x 10⁶ μAM^-1 (r = 0.994),and for UA, (3.2 {plus minus} 0.2) x 10⁶ μAM^-1 (r = 0.991) on GCE/CNTPnaf, both in the presence of 1.0 mM of AA. The detection limits for 8-OHdG and UA on GCE/CNT-Pnaf are around 13x10^-9 M.

Uric acid (UA) was determined in the presence of ascorbic acid (AA) by using a carbon paste electrode modified superficially by a β‐cyclodextrin film (CPE/β‐CD). The surface carbon paste electrode was prepared applying a 30 cycles potential program and using a 1 M HClO₄+0.01 M β‐CD electrolytic solution. The UA and AA solutions were used to evaluate the electrode selectivity and sensitivity by cyclic voltammetric and amperometric methods. In these experiments the detection limit for UA was (4.6±0.01)×10⁻⁶ M and the RSD calculated from the amperometric curves was 10%. From the data obtained it was possible to quantify UA in the urine and saliva samples. Selective detection of UA was improved by formation of an inclusion complex between β‐CD and UA. The results show that the CPE/β‐CD is a good candidate due to its selectivity and sensitivity in the UA determination in complex samples like the biological fluids.