A nitrocellulose/cotton fiber hybrid composite membrane for paper-based biosensor

Abstract

Nitrocellulose (NC) membrane was fabricated and tested for its potential use in various paper-based biosensors for use in point-of-care testing. However, contemporary technologies are complex, expensive, non-scalable, limited by conditions, and beset with potentially adverse effects on the environment. Herein, we proposed a simple, cost-effective, scalable technology to prepare nitrocellulose/cotton fiber (NC/CF) composite membranes. The NC/CF composite membranes with a diameter of 20 cm were fabricated in 15 min using papermaking technology, which contributes to scalability in the large-scale production of these composites. Compared with existing commercial NC membranes, the NC/CF composite membrane is characterized by small pore size (3.59 ± 0.19 μm), low flow rate (156 ± 55 s/40 mm), high dry strength (up to 4.04 MPa), and wet strength (up to 0.13 MPa), adjustable hydrophilic-hydrophobic (contact angles ranged from 29 ± 4.6 to 82.8 ± 2.4°), the good adsorption capacity of protein (up to 91.92 ± 0.07 μg). After lateral flow assays (LFAs) detection, the limit of detection is 1 nM, which is similar to commercial NC membrane (Sartorius CN 140). We envision the NC/CF composite membrane as a promising material for paper-based biosensors of point-of-care testing applications.

Keywords: Cotton fiber; Lateral flow assays; Nitrocellulose; Papermaking technology; Point-of-care testing.

Fig. 1

Schematic of the preparation process of NC/CF composite membrane by papermaking technology and its application for HIV LFAs

Fig. 2

The physical properties of these pure CF membranes and NC/CF composite membranes. A The morphology of these pure CF membranes and NC/CF composite membranes, including front section a and cross section b. B The pore size, porosity of these pure CF membranes and NC/CF composite membranes. C The flow rate of these pure CF membranes and NC/CF composite membranes

Fig. 3

The physical properties of these pure CF membranes and NC/CF composite membranes. A The dry tensile strength of these pure CF membranes and NC/CF composite membranes. B The wet tensile strength of these pure CF membranes and NC/CF composite membranes. C The shape changes of these pure CF membranes and NC/CF composite membranes before and after immersion in water. D The contact angles of these pure CF membranes and NC/CF composite membranes

Fig. 4

The chemical properties of these pure CF membranes and NC/CF composite membranes. The result of EDS images A, FT-IR spectrum B and XRD patterns C

Fig. 5

The adsorption capacity of protein of these pure CF membranes and NC/CF composite membranes. A The standard curve of BSA solution. B The adsorption capacity of protein of these pure CF membranes and NC/CF composite membranes

Fig. 6

HIV detection. A Schematic of LFAs strip. B The detection limit of 10% NC/CF composite membranes was 1 nM. C The detection limit of CNC membrane was 1 nM. D The optical density of test line on 10% NC/CF composite membranes and CNC membranes