Objective:To develop a laser-induced graphene (LIG)-based multimodal electrochemical sensor for monitoring the burn wound microenvironment and to evaluate its performance.Methods:This study was an experimental study. LIG three-electrode substrates were functionalized with L-lactate oxidase, polyaniline, and sortase A to fabricate lactate sensor, pH sensor, and bacterial sensor, respectively, thereby constituting the LIG-based multimodal electrochemical sensor. An electrochemical workstation was used to assess the electrochemical performance of the lactate sensor and bacterial sensor by cyclic voltammetry, with voltammetric response curves being plotted. An electrochemical workstation was used to assess the lactate sensor's response to lactate by chronoamperometry (with current-time curve being recorded and calibration curve being plotted during the test in the L-lactic acid solution with a molar concentration of 10-60 mmol/L), the pH sensor's response to pH by open-circuit potential measurement (with open-circuit potential-time curve being recorded and calibration curve being plotted during the test in the standard buffer solutions with pH values ranging from 3 to 8), and the bacterial sensor's response to bacteria by differential pulse voltammetry (with current-voltage curve being recorded and calibration curve being plotted during the test in gradient suspensions of Staphylococcus aureus ranging from 1×103-1×10? colony forming unit (CFU)/mL). The sample size for all the above experiments was 3. The correlation analysis was performed on the current value of the lactate sensor and the lactate concentration, the average value of steady-state open circuit potential of the pH sensor and the pH value, and the peak current value of the bacterial sensor and the bacterial concentration value. Each of the prepared standard test system solutions for lactate, pH value, and bacteria were all aliquoted into 30 samples. The lactate concentration, pH value, and bacterial concentration were determined by the lactate sensor and a L-lactate assay kit, the pH sensor and a precision pH meter, and the bacterial sensor and a microvolume spectrophotometer, respectively. Fifteen pairs of matched data were selected according to the random number table method for comparison, and the correlation analysis was performed on the measured values of each sensor and the reference values of the corresponding standard methods. Results:The voltammetric response curves showed that the lactate sensor and the bacterial sensor exhibited distinct oxidation peak currents at oxidation peak potentials of approximately 0.74 and 0.65 V, respectively. In the lactate sensor, the change in current after addition of phosphate buffered solution was (0.025±0.041) μA, which was significantly lower than that after addition of L-lactate solution (0.228±0.117) μA ( t=2.85, P<0.05). In the L-lactic acid solution with a molar concentration of 10-60 mmol/L, the current value of the lactate sensor was significantly linearly correlated with the lactate concentration ( r=0.98, P<0.05). In the standard buffer solutions with pH values ranging from 3 to 8, the average value of steady-state open circuit potential of the pH sensor was significantly linearly correlated with the corresponding pH values ( r=0.96, P<0.05). In gradient suspensions of Staphylococcus aureus ranging from 1×103 to 1×10? CFU/mL, the peak current value of the bacterial sensor was significantly linearly correlated with the logarithm of bacterial concentration ( r=0.95, P<0.05). There were no statistically significant differences between the lactate concentrations measured by the lactate sensor and by the L-lactate assay kit, pH values measured by the pH sensor and by the precision pH meter, and logarithmic bacterial concentrations measured by the bacterial sensor and by the microvolume spectrophotometer ( P>0.05), but there were significant positive correlations between the two (with r values of 0.97, 0.96, and 0.95, respectively, P<0.05). Conclusions:After functional modification, the developed LIG-based multimodal electrochemical sensor enables accurate monitoring of lactate concentration, pH value, and bacterial load in the burn wound microenvironment with the results being of high sensitivity and stability. This platform provides a reliable new approach for non-invasive monitoring of the critical indicators of burn wound microenvironment, which shows great prospects for clinical application.

Objective:To develop a laser-induced graphene (LIG)-based multimodal electrochemical sensor for monitoring the burn wound microenvironment and to evaluate its performance.Methods:This study was an experimental study. LIG three-electrode substrates were functionalized with L-lactate oxidase, polyaniline, and sortase A to fabricate lactate sensor, pH sensor, and bacterial sensor, respectively, thereby constituting the LIG-based multimodal electrochemical sensor. An electrochemical workstation was used to assess the electrochemical performance of the lactate sensor and bacterial sensor by cyclic voltammetry, with voltammetric response curves being plotted. An electrochemical workstation was used to assess the lactate sensor's response to lactate by chronoamperometry (with current-time curve being recorded and calibration curve being plotted during the test in the L-lactic acid solution with a molar concentration of 10-60 mmol/L), the pH sensor's response to pH by open-circuit potential measurement (with open-circuit potential-time curve being recorded and calibration curve being plotted during the test in the standard buffer solutions with pH values ranging from 3 to 8), and the bacterial sensor's response to bacteria by differential pulse voltammetry (with current-voltage curve being recorded and calibration curve being plotted during the test in gradient suspensions of Staphylococcus aureus ranging from 1×103-1×10? colony forming unit (CFU)/mL). The sample size for all the above experiments was 3. The correlation analysis was performed on the current value of the lactate sensor and the lactate concentration, the average value of steady-state open circuit potential of the pH sensor and the pH value, and the peak current value of the bacterial sensor and the bacterial concentration value. Each of the prepared standard test system solutions for lactate, pH value, and bacteria were all aliquoted into 30 samples. The lactate concentration, pH value, and bacterial concentration were determined by the lactate sensor and a L-lactate assay kit, the pH sensor and a precision pH meter, and the bacterial sensor and a microvolume spectrophotometer, respectively. Fifteen pairs of matched data were selected according to the random number table method for comparison, and the correlation analysis was performed on the measured values of each sensor and the reference values of the corresponding standard methods. Results:The voltammetric response curves showed that the lactate sensor and the bacterial sensor exhibited distinct oxidation peak currents at oxidation peak potentials of approximately 0.74 and 0.65 V, respectively. In the lactate sensor, the change in current after addition of phosphate buffered solution was (0.025±0.041) μA, which was significantly lower than that after addition of L-lactate solution (0.228±0.117) μA ( t=2.85, P<0.05). In the L-lactic acid solution with a molar concentration of 10-60 mmol/L, the current value of the lactate sensor was significantly linearly correlated with the lactate concentration ( r=0.98, P<0.05). In the standard buffer solutions with pH values ranging from 3 to 8, the average value of steady-state open circuit potential of the pH sensor was significantly linearly correlated with the corresponding pH values ( r=0.96, P<0.05). In gradient suspensions of Staphylococcus aureus ranging from 1×103 to 1×10? CFU/mL, the peak current value of the bacterial sensor was significantly linearly correlated with the logarithm of bacterial concentration ( r=0.95, P<0.05). There were no statistically significant differences between the lactate concentrations measured by the lactate sensor and by the L-lactate assay kit, pH values measured by the pH sensor and by the precision pH meter, and logarithmic bacterial concentrations measured by the bacterial sensor and by the microvolume spectrophotometer ( P>0.05), but there were significant positive correlations between the two (with r values of 0.97, 0.96, and 0.95, respectively, P<0.05). Conclusions:After functional modification, the developed LIG-based multimodal electrochemical sensor enables accurate monitoring of lactate concentration, pH value, and bacterial load in the burn wound microenvironment with the results being of high sensitivity and stability. This platform provides a reliable new approach for non-invasive monitoring of the critical indicators of burn wound microenvironment, which shows great prospects for clinical application.