"Biomimetic-electrochemical-sensory-platform" for biomolecule free cocaine testing.

A biomimetic cocaine sensor was fabricated by using poly(p-phenylene) (PPP) with cyclodextrin (CD) units in the backbone and poly(ethylene glycol) (PEG) side chains (PPP-CD-g-PEG). The sensory platform was constructed by one step surface modification of glassy carbon electrode with PPP-CD-g-PEG by drop coating. The electrochemical measurements are based on the formation of CD-cocaine inclusion complex on the surface resulting in a significant decrease in electron transfer capacity of the selected redox probe. The changes in the surface features due to cocaine binding were explored via electrochemical techniques such as differential pulse voltammetry, cyclic voltammetry and electrochemical impedance spectrometry. The sensor exhibited linearity in the range of 25-200 nM cocaine, LOD was calculated as 28.62 nM (n = 5) according to 3Sb/m formula. Finally, the sensory platform was successfully applied for the cocaine analysis in synthetic urine samples and correlated with the chromatographic method.

Mobile Phone Sensing of Cocaine in a Lateral Flow Assay Combined with a Biomimetic Material.

Lateral flow assays (LFAs) are an ideal choice for drug abuse testing favored by their practicability, portability, and rapidity. LFA based on-site rapid screening devices provide positive/negative judgment in a short response time. The conventionally applied competitive assay format used for small molecule analysis such as abused drugs restricts the quantitation ability of LFA strips. We report herein, for the first time, a new strategy using the noncompetitive assay format via a biomimetic material, namely, poly(p-phenylene) ß-cyclodextrin poly(ethylene glycol) (PPP-CD-g-PEG) combined with gold nanoparticle (AuNP) conjugates as the labeling agent to recognize the target cocaine molecule in the test zone. The intensities of the visualized red color in the test line indicate that the cocaine concentrations were analyzed via a smartphone application. Significantly, a combination of this platform with a smartphone application provides quantitative data on the cocaine amount, making it a very inventive and attractive approach especially for on-site applications at critical points such as traffic stops and the workplace.