Abstract
Two-needle 3D stochastic microsensors based on boron- and nitrogen-decorated gra-phenes, modified with N-(2-mercapto-1H-benzo[d]imidazole-5-yl), were designed and used for the molecular recognition and quantification of CA 72-4, CA 19-9, CEA and CA 125 biomarkers in biological samples such as whole blood, urine, saliva and tumoral tissue. The NBGr-2 sensor yielded lower limits of determination. For CEA, the LOD was 4.10 × 10(-15) s(-1) g(-1) mL, while for CA72-4, the LOD was 4.00 × 10(-11) s(-1) U(-1) mL. When the NBGr-1 sensor was employed, the best results were obtained for CA12-5 and CA19-9, with values of LODs of 8.37 × 10(-14) s(-1) U(-1) mL and 2.09 × 10(-13) s(-1) U(-1) mL, respectively. High sensitivities were obtained when both sensors were employed. Broad linear concentration ranges favored their determination from very low to higher concentrations in biological samples, ranging from 8.37 × 10(-14) to 8.37 × 10(3) s(-1) U(-1) mL for CA12-5 when using the NBGr-1 sensor, and from 4.10 × 10(-15) to 2.00 × 10(-7) s(-1) g(-1) mL for CEA when using the NBGr-2 sensor. Student's t-test showed that there was no significant difference between the results obtained utilizing the two microsensors for the screening tests, at a 99% confidence level, with the results obtained being lower than the tabulated values.