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 -1 magnitude order) were recorded (5.12 pg mL -1 for the sensor based on silk at pH 7.40 and on copy paper at pHs 3.00 and 7.40; 16 ng mL -1 at pH 7.40 for the sensor based on plastic, 41.00 pg mL -1 for the sensor based on silk at pH 3.00, and 204.00 pg mL -1 for the sensor based on plastic, at pH 3.00), with wide linear concentration ranges (5.12 × 10 -12 -2.00 × 10 -6  g mL -1 for the sensors based on silk at pH 7.40, and on copy paper at pH 3.00; 5.12 × 10 -12 -8.00 × 10 -7  g mL -1 for the sensor based on copy paper at pH 7.40; 1.60 × 10 -8 -2.00 × 10 -6  g mL -1 for the sensor based on plastic at pH 7.40; 4.10 × 10 -14 -2.00 × 10 -6  g mL -1 for the sensor based on silk, at pH 3.00; and 2.04 × 10 -13 -8.00 × 10 -7  g mL -1 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%.