Electrochemical aptasensor fabricated by anchoring recognition aptamers and immobilizing redox probes on bipolar silica nanochannel array for reagentless detection of carbohydrate antigen 15-3

Abstract

Timely, convenient, and efficient detection of carbohydrate antigen 15-3 (CA15-3) levels in serum holds significant importance in early screening, diagnostic assistance and prognosis prediction of breast cancer. The development of efficient and convenient electrochemical aptasensors with immobilized redox probes for label-free detection of CA15-3 is highly desirable. In this work, a bipolar silica nanochannel array film (bp-SNA) with two distinct functional domains including nanochannels and an outer surface was employed for the immobilization of recognition ligands and electrochemical redox probes, enabling the construction of a probe-integrated aptasensor for reagentless electrochemical detection of CA15-3. Cost-effective and readily available indium tin oxide (ITO) was used as the supporting electrode for sequential growth of a negatively charged inner layer (n-SNA) followed by a positively charged outer layer (p-SNA). The preparation process of bp-SNA is convenient. Functionalization of amino groups on the outer surface of bp-SNA was modified by aldehyde groups for covalent immobilization of recognition aptamers, further establishing the recognition interface. Within the nanochannels of bp-SNA, the electrochemical redox probe, tri (2,2′-dipyridyl) cobalt (II) (Co(bpy)32+) was immobilized, which experienced a dual effect of electrostatic attraction from n-SNA and electrostatic repulsion from p-SNA, resulting in high stability of the immobilized probes. The constructed aptasensor allowed for reagentless electrochemical detection of CA15-3 ranged from 0.001 U/mL to 500 U/mL with a low detection limit (DL), 0.13 mU/mL). The application of the constructed aptasensor for CA15-3 detection in fetal bovine serum was also validated. This sensor offers advantages of a simple and readily obtainable supporting electrode, easy bp-SNA fabrication, high probe stability and good stability.

Highly Sensitive Electrochemical Determination of Butylated Hydroxyanisole in Food Samples Using Electrochemical-Pretreated Three-Dimensional Graphene Electrode Modified with Silica Nanochannel Film

“…VMSF is composed of a vertical array of nanochannels perpendicular to the electrode, uniform nanochannel sizes (typically 2-3 nm in diameter), high pore density (up to 10 12 /cm 2 ), adjustable thickness (usually 50-200 nm), and good chemical stability [43][44][45]. Compared to the morphologies of other porous silica materials, these characteristics provide VMSF with rapid mass transfer capabilities and size and electrostatic sieving capabilities at the molecular level [46][47][48][49][50]. For instance, it has been proven that the monomer of microperoxidase-11 (MP-11, Mw 1861, size: 1.1 × 1.7 × 3.3 nm), a hemecontaining peptide with only 11 amine acids, can enter the nanochannels of VMSF through adsorption.…”