# Paper Matters: Technical Evaluation of Paper-Based Substrates for Enhanced Preconcentration of Biomolecules in Liquid Biopsy Diagnostics

## TL;DR

This paper shows how different types of paper can be used to improve the detection of disease biomarkers in a simple and low-cost way.

## Contribution

The study introduces a novel use of paper-based substrates for preconcentration of biomolecules in diagnostics.

## Key findings

- Up to 20-fold enhancement in miRNA detection in human serum within 30 seconds.
- Paper platforms showed 10-fold and 2-fold improvements for DNA and proteins, respectively.
- Substrate choice significantly affects analyte accumulation and detection efficiency.

## Abstract

Early detection of
disease biomarkers remains a major challenge
due to their low abundance in biological fluids. Preconcentration
strategies can address this issue, but conventional approaches often
require additional time, costly materials, or complex instrumentation.
This work explores the use of paper-based substrates as a sustainable
and cost-effective alternative for analyte preconcentration, highlighting
how the choice of paper type critically influences sensitivity enhancement
in analytical methods without compromising simplicity. Three cellulose-based
papers (Whatman grade 1, Whatman grade 4, and a commercial laboratory
filter paper) were systematically characterized and configured as
3D-origami-inspired, capillary-driven platforms. Their structural
and fluidic properties were evaluated to determine how substrate selection
affects analyte accumulation, transport, and detection efficiency.
The devices were combined with three detection assays: a naked-eye
colorimetric assay with smartphone integration, an electrochemical
assay for miRNA, and a spectrophotometric Bradford assay for protein
quantification. The paper platforms demonstrated rapid and efficient
preconcentration across multiple biomarker classes. Up to a 20-fold
enhancement was achieved for miRNA detection in human serum within
30 s, approximately 10-fold for short and double-stranded DNA in buffer,
and about 2-fold for larger proteins. These results illustrate the
importance of substrate selection and the versatility of paper-based
preconcentration in handling analytes of different molecular sizes
and assay formats. This study shows that cost-effective, customizable
paper substrates can bridge the gap between high-performance biomolecular
analysis and accessible diagnostics, enabling early disease detection
and real-time monitoring in both laboratory and point-of-care settings.