Electrochemical Aptasensor for Ultralow Fouling Cancer Cell Quantification in Complex Biological Media Based on Designed Branched Peptides

Abstract

The rapid, convenient, and selective assaying of clinical targets directly in complex biological media brings with it the potential to revolutionize diagnostics. One major hurdle to impact is retention of selectivity and a tight control of nonspecific surface interactions or biofouling. We report herein, the construction of an antifouling interface through the covalent attachment of designed branched zwitterionic peptides onto electrodeposited polyaniline film. The antifouling capability of the designed branched peptide significantly outperforms that of the commonly used PEG and linear peptides. The interfaces modified with branched peptides are exceptionally effective in reducing a nonspecific protein and cell adsorption, as verified by electrochemical and fluorescent characterization. The derived sensors with mucin1 protein (MUC1) aptamer as the recognition element detect MUC1-positive MCF-7 breast cancer cells in human serum with high sensitivity and selectivity. The linear response range of the cytosensor for the MCF-7 cell is from 50 to 106 cells/mL, with a limit of detection as low as 20 cells/mL. More importantly, the assaying performances remain unchanged in human serum owing to the presence of branched antifouling peptide, indicating feasibility of the cytosensor for practical cancer cell quantification in complex samples.

Dealing with the Foreign‐Body Response to Implanted Biomaterials: Strategies and Applications of New Materials

“…reported that peptide‐based self‐assembled monolayers are highly resistant to protein adsorption. [ 284 ] Subsequently, two main types of antifouling polypeptides were developed and have been reported to have immunomodulatory functions, the PEG peptides, [ 285 ] and the zwitterionic peptides that consist of both positively charged amino acids (lysine, arginine) and negatively charged amino acids (aspartic acid or glutamic acid), [ 286–292 ] or amino acid units with balanced charges. [ 293–295 ]…”

Design Strategies for Electrochemical Aptasensors for Cancer Diagnostic Devices

“…Aptamer self-assembly through chemisorption of the thiol linker-modified aptamers onto the gold surface is possibly the most popular approach, despite its suffering from insufficient long-term stability [64]. Typically, the alkanethiol-linker functionalised aptamers are self-assembled on gold electrodes through the sulphur-gold linkage complemented by filling the unblocked spaces/pinholes in the self-assembled monolayers (SAM) formed by the aptamers with alkanethiols [65,66], dithiols [67,68] or antifouling agents [69,70]. The most stable immobilisation is achieved through the affinity binding between the biotinylated aptamer sequence and avidin- [71], streptavidin- [72] or neutravidin-modified electrodes [73].…”

Electrochemical Sensors for Detection of Markers on Tumor Cells

“…After a series of optimization processes, they finally obtained a high-quality sensor for MCF-7 cells, with a detection range of 50–1.0 × 10 6 cells/mL and a detection limit of 5 cells/mL [ 18 ]. In order to prevent nonspecific binding and improve specificity, Liu et al developed an antifouling electrochemical-cell-based biosensor to detect MCF-7 cells in a complex biological environment [ 19 ]. In this work, polyaniline membrane was electrodeposited on an electrode to support the MUC1 aptamer and an investigator-designed antifouling branched peptide ( Figure 3 ).…”

“…The structure of the synthetic branched peptide is shown on the left. Reproduced with permission from [ 19 ], American Chemical Society, 2019.…”