Ricardo Antonio Escalona Villalpando

This paper presents a design methodology aimed at unconventional users, specifically dogs, in response to the problem of noise pollution. Traditionally, design has favored an anthropocentric approach, focused onto human needs; however, the growing formation of multispecies families requires expanding the scope of action to living beings unable to directly voice their perceptions. In this context, the research proposes a methodological process built upon the interpretation of the owner as a mediator of the animal's responses, by incorporating semi-structured interviews, observational tools, and comparative qualitative analyses (QCA). The proposal is structured in seven different stages. The implementation of QCA is an innovative contribution, as it allows for the evaluation of causative configurations between variables, namely, noise reduction, ornamentation, pet restfulness, as well as ethological training, linking them to improvements in quality of life of the human-dog tandem. Preliminary data shows that the methodology facilitates generating solutions which more efficiently satisfy the animal's real needs, as it is based on behavior as documented by their owners. Also, it addresses the pertinence of accounting for canine auditory well-being and the physiological and behavioral consequences of exposure to loud noises. In conclusion, this methodology proposal contributes to dignifying non-conventional users by means of an adaptable and repeatable framework that transcends anthropocentrism and promotes innovation in contemporary design.

Co₃O₄-based materials have multiple applications in the field of materials, especially in sensor technology. In this work, Co₃O₄ nanoparticles were synthesized using a chemical method. The crystalline phase and crystal size were investigated by XRD, the morphology by SEM and the oxidation states by XPS techniques. The Co₃O₄ material was used to immobilize the urate oxidase enzyme (UOx), which showed a higher current density (1.6 times higher) than the enzyme alone in cyclic voltammetry in phosphate buffer pH 5.6. GCE/Co₃O₄/UOx achieved a linear range of 3.7–500 µM and a higher sensitivity of 65 µA mM⁻¹ cm⁻² compared to 45 µA mM⁻¹ cm⁻² achieved by the enzyme alone in a uric acid sensor. The favorable activity of GCE/Co₃O₄/UOx enabled its use in a miniaturized device with low sample volume using artificial and real human sweat. The device was used to quantify uric acid levels in five samples and showed a relative error between the calculated and expected value of less than 10%. The implementation of GCE/Co₃O₄/UOx is attractive in a biosensor that can be used as a uric acid sensor in biological fluids.

Conventionally, the optimization of glucose biosensors is achieved by varying the concentrations of the individual reagents used to immobilize the enzyme. In this work, the effect and interaction between glucose oxidase enzyme (GOx), ferrocene methanol (Fc), and multi-walled carbon nanotubes (MWCNTs) at different concentrations were investigated by a design of experiments (DoE). For this analysis, a factorial design with three factors and two levels each was used with the software RStudio for statistical analysis. The data were obtained by electrochemical experiments on the immobilization of GOx-Fc/MWCNT at different concentrations. The results showed that the factorial DoE method was confirmed by the non-normality of the residuals and the outliers of the experiment. When examining the effects of the variables, analyzing the half-normal distribution and the effects and contrasts for GOx-Fc/MWCNT, the factors that showed the greatest influence on the electrochemical response were GOx, MWCNT, Fc, and MWCNT:Fc, and there is a high correlation between the factors GOx, MWCNT, Fc, and MWCNT:Fc, as shown by the analysis of homoscedasticity and multicollinearity. With these statistical analyses and experimental designs, it was possible to find the optimal conditions for different factors: 10 mM mL⁻¹ GOx, 2 mg mL⁻¹ Fc, and 15 mg mL⁻¹ MWCNT show a greater amperometric response in the glucose oxidation. This work contributes to advancing enzyme immobilization strategies for glucose biosensor applications. Systematic investigation of DoE leads to optimized immobilization for GOx, enables better performance as a glucose biosensor, and allows the prediction of some outcomes. Graphical Abstract Schematic representation of the study of factors to optimize the performance of a glucose biosensor by design of experiments.

The urine/urea oxidation reaction through catalysts with a higher performance in direct urea microfluidic fuel cells (DUµFC) is a promising method for power generation due to the large amount of human and animal urine containing 2–2.5 wt% urea. This paper presents a study that used urea as fuel in a DUµFC in the presence of palladium supported by reduced graphene oxide (rGO) for power generation. Some parameters, such as urea, KOH and H₂SO₄ concentration and flux rate, among others, are optimized in order to carry out the evaluation of urine samples as fuel in an air-breathing microfluidic fuel cell. The results show that the Pd/rGo catalyst mixed with Nafion^® in the anodic compartment is dispersed and attached to the paper fibers, generating electrical contact and giving rise to the reactions of interest. In addition, XRD analysis confirmed the successful deposition of Pd and rGo on the substrate. These electrochemical results are promising, since, despite the decrease in the general performance of the DUµFC under ideal conditions with respect to normal cells, the generation of energy from urine was demonstrated.

An efficient immobilization of Glucose oxidase (GOx) on an appropriate substrate is one of the main challenges of developing fuel cells that allow energy to be obtained from renewable substrates such as carbohydrates in physiological environments. The research importance of biofuel cells relies on their experimental robustness and high compatibility with biological organisms such as tissues or the bloodstream with the aim of obtaining electrical energy even from living systems. In this work, we report the use of 5,10,15,20 tetrakis (1-methyl-4-pyridinium) porphyrin and glutathione capped CdTe Quantum dots (GSH-CdTeQD) as a support matrix for the immobilization of GOx on carbon surfaces. Fluorescent GSH-CdTeQD particles were synthesized and their characterization by UV-Vis spectrophotometry showed a particle size between 5–7 nm, which was confirmed by DLS and TEM measurements. Graphite and Toray paper electrodes were modified by a drop coating of porphyrin, GSH-CdTeQD and GOx, and their electrochemical activity toward glucose oxidation was evaluated by cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. Additionally, GOx modified electrode activity was explored by scanning electrochemical microscopy, finding that near to 70% of the surface was covered with active enzyme. The modified electrodes showed a glucose sensitivity of 0.58 ± 0.01 μA/mM and an apparent Michaelis constant of 7.8 mM. The addition of BSA blocking protein maintained the current response of common interferent molecules such as ascorbic acid (AA) with less than a 5% of interference percentage. Finally, the complex electrodes were employed as anodes in a microfluidic biofuel cell (μBFC) in order to evaluate the performance in energy production. The enzymatic anodes used in the μBFC allowed us to obtain a current density of 7.53 mAcm⁻² at the maximum power density of 2.30 mWcm⁻²; an open circuit potential of 0.57 V was observed in the biofuel cell. The results obtained suggest that the support matrix porphyrin and GSH-CdTeQD is appropriate to immobilize GOx while preserving the enzyme’s catalytic activity. The reported electrode arrangement is a viable option for bioenergy production and/or glucose quantification.

This work reports on Fe₂O₃ and ZnO materials for lactate quantification. In the synthesis, the bi-phase γ-/α-Fe₂O₃ and γ-/α-Fe₂O₃/ZnO nanoparticles (NPs) were obtained for their application in a lactate colorimetric sensor. The crystalline phases of the NPs were analyzed by XRD and XPS techniques. S/TEM images showed spheres with an 18 nm average and a needle length from 125 to 330 nm and 18 nm in diameter. The γ-/α-Fe₂O₃ and γ-/α-Fe₂O₃/ZnO were used to evaluate the catalytic activity of peroxidase with the substrate 3,3,5,5-tetramethylbenzidine (TMB), obtaining a linear range of 50 to 1000 μM for both NPs, and a 4.3 μM and 9.4 μM limit of detection (LOD), respectively. Moreover, γ-/α-Fe₂O₃ and γ-/α-Fe₂O₃/ZnO/lactate oxidase with TMB assays in the presence of lactate showed a linear range of 50 to 1000 µM, and both NPs proved to be highly selective in the presence of interferents. Finally, a sample of human serum was also tested, and the results were compared with a commercial lactometer. The use of ZnO with Fe₂O₃ achieved a greater response toward lactate oxidation reaction, and has implementation in a lactate colorimetric sensor using materials that are economically accessible and easy to synthesize.

This study reports the performance of simple low-cost synthesized bifunctional Cu/Cu₂O nanoparticles (NPs) used as a catalyst for energy-harvesting applications through of a microfluidic fuel cell (µFC), and further, as cholesterol (Chol) sensor. TEM characterization of the NPs showed spheres between 4 and 10 nm, while XRD and XPS analysis confirmed the composition and preferential crystallographic plane of Cu/Cu₂O. In addition, 25.26 m² g⁻¹ surface area was obtained, which is greater than those commercial materials. NPs showed high activity toward the cholesterol oxidation reaction when were used as a sensor, obtaining a linear interval between 0.5 and 1 mM and 850 µA mM⁻¹ mg⁻¹ of sensitivity and 8.9 µM limit of quantification LOQ. These values are comparable to results previously reported. Moreover, Cu/Cu₂O NPs were used as anode in a µFC with 0.96 V of cell voltage and 6.5 mA cm⁻² and 1.03 mW cm⁻² of current and power density, respectively. This performance is the highest currently reported for cholesterol application as an alternative fuel, and the first one reported for a microfluidic fuel cell system as far as is known. Results showed that the obtained Cu-based NPs presented an excellent performance for the dual application both µFC and sensor, which has potential applications in biomedicine and as an alternative energy source.