2D disposable stochastic sensors for molecular recognition and quantification of maspin in biological samples.

Three disposable stochastic sensors using nanolayer deposition of a graphene nanocomposite comprising graphene nanoparticles and gold nanoparticles, on different supports: silk, plastic, and paper, and modified with chitosan, were characterized and validated for molecular recognition and quantification of maspin in biological samples. Very low limits of determination (of pg mL magnitude order) were recorded (5.12 pg mL for the sensor based on silk at pH 7.40 and on copy paper at pHs 3.00 and 7.40; 16 ng mL at pH 7.40 for the sensor based on plastic, 41.00 pg mL for the sensor based on silk at pH 3.00, and 204.00 pg mL for the sensor based on plastic, at pH 3.00), with wide linear concentration ranges (5.12 × 10-2.00 × 10 g mL for the sensors based on silk at pH 7.40, and on copy paper at pH 3.00; 5.12 × 10-8.00 × 10 g mL for the sensor based on copy paper at pH 7.40; 1.60 × 10-2.00 × 10 g mL for the sensor based on plastic at pH 7.40; 4.10 × 10-2.00 × 10 g mL for the sensor based on silk, at pH 3.00; and 2.04 × 10-8.00 × 10 g mL for the sensor based on plastic at pH 3.00) allowing the molecular recognition and quantification of maspin in healthy people and patients with gastric cancer, when a potential of 125 mV vs. Ag/AgCl was applied. The recoveries of maspin in whole blood, saliva, urine, and tissue samples were higher than 95.00%, with a relative standard deviation lower than 1.0%.