Microfluidic biochip platform sensitized by AgNPs for SERS based rapid detection of uric acid

Abstract

Herein, a novel Microfluidic-biochip enabled with Surface Enhanced Raman Spectroscopy (SERS) as a readout has been demonstrated for Uric acid (UA) detection as point-of care device. Three different biochip designs (D1, D2 and D3) containing pillars in a microchannel with different bending ratios were conceived and optimized for various mixing parameters using a multiphysics simulation tool. The microchannel, integrated with pillars, provide pressure perturbation, sharp corners, and variation in bending ratio improves phase shift and mixing index. Subsequently the microfluidic-biochips were fabricated by a combination of photo-and soft-lithography, and bonding strength between two PolyDiMethylSiloxane (PDMS) substrates were found stable up to a flow rate of 1.8ml/min. Further to realize SERS activity in the microfluidic-biochip, cubic shape silver nanoparticles (AgNPs), with an average size ~68 nm, were synthesized using poly-ol method. The SERS activity was optimized by simultaneously flowing AgNPs and crystal violet (CV) dye of 10-6 M, with double inlet in the reservoir and highest sensitivity was achieved in the D3 biochip. Further, D3 biochip was employed for detection of extended concentrations of CV and UA. The Enhancement factor (EF) limit of detection (LoD) and Relative standard deviation (RSD) was found to be 2x107, 8.9x10-11 and 2.7% respectively for CV and 3.1x103, 3.2x10-7 and 2.9% respectively for UA. Interference of UA with lactic acid (LA) has been tested and device was able to detect signature peaks of both biomarkers up to 50x10-9M concentration. Thus, the developed Microfluidic-biochip device has potential to be used in a point of care (POC) setting for onsite detection of biomarkers.

Disposable Point-of-Care Electrochemical Sensor for Uric Acid Determination in Human Urine Utilizing a Pencil Graphite Electrode Modified with Polydopamine/Gold Nanoparticles

“…35 Electrodeposition of gold nanoparticles on PGE/PDA.-Incorporating metallic and non-metallic NPs into electrochemical sensors is a widely recognized and effective method due to their amplified influence on electron transfer kinetics between the electrode surface and a diverse array of compounds. [36][37][38][39][40][41][42] Table I. Effect of different PGEs modification on the electrode to electrode response reproducibility towards 1.0 × 10 −4 mol l −1 uric acid oxidation in PBS (pH 7.4).…”

Single‐platform, Attomolar Detection of Multiple Biomarkers by a Flexible SERS Sensor

“…for 1236 cm −1 peak of Aβ 1‐42 and 1249 cm −1 peak of HI for calculating LoD values. The LoD value was calculated by the formula $${LoD=\ 3\sigma /d}$$ , where $${{ {^\prime}}\sigma { {^\prime}}}$$ is the standard deviation and ‘d’ is the slope of the calibration graph [34] . The LoD values of Aβ 1‐42 and HI were found to be 76×10 −18 M (Figure 7c) and 26×10 −18 M (Figure 7d), respectively.…”

“…An added possible mechanism can be non‐covalent interaction between the analyte molecules and purine‐based ligand (L) [30] . Enhancement factor (EF) on P 3 /AgNPs SERS sensor for the biomarkers (Aβ 1‐42 and HI) were calculated by the formula EF=(I SERS /I s )×(C s /C SERS ) [34] . The enhancement factor (EF) was found to be 3.1×10 12 and 6.6×10 12 for Aβ 1‐42 and HI respectively, as shown in Figure 8b.…”

“…The LoD value was calculated by the formula LoD ¼ 3s=d, where 0 s 0 is the standard deviation and 'd' is the slope of the calibration graph. [34] The LoD values of Aβ 1-42 and HI were found to be 76 × 10 À 18 M (Figure 7c) and 26 × 10 À 18 M (Figure 7d), respectively.…”

“…[30] Enhancement factor (EF) on P 3 /AgNPs SERS sensor for the biomarkers (Aβ 1-42 and HI) were calculated by the formula EF = (I SERS /I s ) × (C s /C SERS ). [34] The enhancement factor (EF) was found to be 3.1 × 10 12…”