Enhanced Performance of Reagent-Less Carbon Nanodots Based Enzyme Electrochemical Biosensors

Abstract

This work reports on the advantages of using carbon nanodots (CNDs) in the development of reagent-less oxidoreductase-based biosensors. Biosensor responses are based on the detection of H2O2, generated in the enzymatic reaction, at 0.4 V. A simple and fast method, consisting of direct adsorption of the bioconjugate, formed by mixing lactate oxidase, glucose oxidase, or uricase with CNDs, is employed to develop the nanostructured biosensors. Peripherical amide groups enriched CNDs are prepared from ethyleneglycol bis-(2-aminoethyl ether)-N,N,N′,N′-tetraacetic acid and tris(hydroxymethyl)aminomethane, and used as precursors. The bioconjugate formed between lactate oxidase and CNDs was chosen as a case study to determine the analytical parameters of the resulting L-lactate biosensor. A linear concentration range of 3.0 to 500 µM, a sensitivity of 4.98 × 10−3 µA·µM−1, and a detection limit of 0.9 µM were obtained for the L-lactate biosensing platform. The reproducibility of the biosensor was found to be 8.6%. The biosensor was applied to the L-lactate quantification in a commercial human serum sample. The standard addition method was employed. L-lactate concentration in the serum extract of 0.9 ± 0.3 mM (n = 3) was calculated. The result agrees well with the one obtained in 0.9 ± 0.2 mM, using a commercial spectrophotometric enzymatic kit.

Designing of Nanomaterials-Based Enzymatic Biosensors: Synthesis, Properties, and Applications

“…Bravo et al used a simple and fast method to produce a lactate biosensor, which consisted of the direct adsorption of lactate oxidase onto carbon nanodots. Their biosensor had a sensitivity of 4.98 × 10 −3 µA•µM −1 and a detection limit of 0.9 µM, similar to the commercial spectrophotometric enzymatic kit [322].…”

“…The use of nanomaterials, and more specifically, of those that are carbon-based, can effectively solve the lower sensitivity and selectivity issues in LODs. Using these nanomaterials also increases the longevity of lactate biosensors [322][323][324][325].…”

Carbon Nanomaterials (CNMs) and Enzymes: From Nanozymes to CNM-Enzyme Conjugates and Biodegradation

“…The most popular target molecule is glucose for biometric health monitoring ( Table 2 ) [ 224 , 227 , 228 , 237 , 249 , 269 , 271 , 273 ]. However, biosensors have been developed to detect many other bioactive compounds too, such as cholesterol [ 312 , 370 , 371 ] and triglycerides [ 282 ], lactose [ 220 ] and lactate [ 225 , 280 ], neurotransmitters [ 234 , 240 , 246 , 278 , 279 , 372 ] and hormones [ 239 ], various disease biomarkers [ 244 , 257 , 261 ], microRNAs [ 223 ], drugs [ 218 , 287 ], pathogens [ 219 ] and toxins [ 221 ], xanthine [ 262 ] and caffeic acid [ 373 ], p -coumaric acid [ 232 ], ferulic acid [ 233 ], trace metals [ 274 ], and oxygen [ 268 ].…”

Electrochemiluminescence Biosensors Using Screen-Printed Electrodes

“…Therefore, methods with high sensitivity and good selectivity for the fast and dynamic lactate concentration response of lactate in human serum or other body fluids are urgently demanded. Lox-based biosensors for the determination of lactate in serum have been reported [ 112 ]. An ECL biosensor based on LOx and luminol with a higher sensitivity has been developed for the determination of this analyte in sweat [ 113 ].…”

“…There are many nanomaterials used now for the development of enzymatic biosensors and their nature is broad, such as metallic nanoparticles of silver (AgNPs) [ 127 ] and gold (AuNPs) [ 128 ]; carbon nanomaterials as carbon nanodots (CNDs) [ 112 ], graphene [ 129 ] and carbon nanotubes (CNTs) [ 130 ]; and biochar [ 131 ]. Semiconductors such as quantum dots (QDs) [ 132 ] and silicates [ 133 ] are also investigated.…”