Functionalized graphene oxide for the fabrication of paraoxon biosensors

• Published in: Analytica chimica acta 2014-05, Vol.827, p.86-94
• Main Authors: Zhang, Hangyu, Li, Zhe-fei, Snyder, Alexandra, Xie, Jian, Stanciu, Lia A.
• Format: Article
• Language: English
• Subjects: 4-Aminobenzoic Acid - chemistry; Acetylcholinesterase - chemistry; Acetylcholinesterase - metabolism; AChE; Affinity; Binding Sites; Biosensing Techniques - methods; Biosensors; Chelation; Cobalt - chemistry; Electrochemistry; Electrodes; Enzymes, Immobilized - chemistry; Enzymes, Immobilized - metabolism; Functionalization; Graphene; Graphene oxide; Graphite - chemistry; Graphite - metabolism; Histidine - chemistry; Limit of Detection; Lysine - chemistry; Nanomaterials; Nickel; Nickel - chemistry; Oxides; Oxides - chemistry; Paraoxon - analysis; Pesticide biosensor; Pesticide Residues - analysis; Strategy
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/j.aca.2014.04.014

[Display omitted] •We developed functionalized graphene oxide (FGO) as a platform for biosensors.•Abundant affinity groups on FGO resulted in an excellent enzyme loading.•The modified electrodes exhibited great short-term and long-term stability.•The FGO biosensors showed a detection limit of 0.65nM to paraoxon. There is an increasing need to develop biosensors for the detection of harmful pesticide residues in food and water. Here, we report on a versatile strategy to synthesize functionalized graphene oxide nanomaterials with abundant affinity groups that can capture histidine (His)-tagged acetylcholinesterase (AChE) for the fabrication of paraoxon biosensors. Initially, exfoliated graphene oxide (GO) was functionalized by a diazonium reaction to introduce abundant carboxyl groups. Then, Nα,Nα-bis(carboxymethyl)-l-lysine hydrate (NTA-NH2) and Ni2+ were anchored onto the GO based materials step by step. AChE was immobilized on the functionalized graphene oxide (FGO) through the specific binding between Ni-NTA and His-tag. A low anodic oxidation potential was observed due to an enhanced electrocatalytic activity and a large surface area brought about by the use of FGO. Furthermore, a sensitivity of 2.23μAmM−1 to the acetylthiocholine chloride (ATChCl) substrate was found for our composite covered electrodes. The electrodes also showed a wide linear response range from 10μM to 1mM (R2=0.996), with an estimated detection limit of 3μM based on an S/N=3. The stable chelation between Ni-NTA and His-tagged AChE endowed our electrodes with great short-term and long-term stability. In addition, a linear correlation was found between paraoxon concentration and the inhibition response of the electrodes to paraoxon, with a detection limit of 6.5×10−10M. This versatile strategy provides a platform to fabricate graphene oxide based nanomaterials for biosensor applications.