A wash-free, elution-free and low protein adsorption paper-based material for nucleic acid extraction

Nucleic acid detection technologies have been widely utilized for various diseases. Conventional laboratory tests are less suitable for use in resource-limited settings as they are time-consuming, high-cost, complex, and heavily dependent on benchtop equipment. Rapid nucleic acid detection methods that consist of rapid nucleic acid extraction steps could overcome these challenges. A paper-based platform has been utilized to develop various rapid nucleic acid extraction methods owing to its cost-effectiveness, portability, and easy-modification. However, the existing paper-based nucleic acid extraction technologies mainly focus on improving the adsorption capacity of nucleic acids without reducing the non-specific adsorption capacity of proteins. In this study, paper-based nucleic acid extraction technology with wash-free, elution-free, and low protein adsorption was developed. The fabrication of paper involves the mixing of polyethylene glycol (PEG)-modified cotton fiber, chitosan (COS)-modified cotton fiber, and cotton fiber to form PEG-modified cotton fiber/chitosan-modified cotton fiber/cotton fiber (PEG-CF/COS-CF/CF) paper by the wet molding method. The result showed that PEG-CF/COS-CF/CF paper has a desirable pore size (23.9 ± 4.03 μm), good mechanical strength (dry: 9.37 Mpa and wet: 0.28 Mpa), and hydrophilicity (contact angle: 42.6° ± 0.36°). NH₃⁺ groups of COS and OH^- groups of PEG were observed on its surface and the adsorption efficiency of nucleic acid in TE buffer was 42.48% ± 0.30%. The limit of detection of pure DNA with this PEG-CF/COS-CF/CF paper by qPCR was as low as 25 ng. Additionally, this platform could successfully extract nucleic acid from 30 μL of a saliva sample, highlighting its potential use for clinical sample testing. The proposed paper-based nucleic acid extraction platform shows tremendous potential for disease diagnosis in resource-limited settings.