# Integrated 3D-Printed Microfluidic Device for Immunocapture and Electrochemical Assessment of Transferrin Saturation in Point-of-Care Stroke Diagnostics

## TL;DR

This paper introduces a 3D-printed device that quickly and accurately measures a stroke-related biomarker using a small blood sample, enabling faster point-of-care diagnostics.

## Contribution

The novel contribution is an integrated 3D-printed microfluidic device combining immunocapture and electrochemical detection for rapid transferrin saturation assessment.

## Key findings

- The device achieves accurate and precise TSAT assessment within 60 minutes using only 50 μL of sample.
- Strong correlation and agreement with the urea-PAGE reference method were demonstrated in human serum samples.
- The device supports rapid point-of-care testing for ischemic stroke and broader clinical diagnostics.

## Abstract

A 3D-printed electrochemical microfluidic device (3D-EMD)
was developed
to assess the transferrin saturation (TSAT) biomarker in ischemic
stroke patients. The all-in-one 3D-EMD integrates a strategically
engineered immunoassay module for the direct and selective isolation
of transferrin (Tf) from unpretreated clinical samples, unaffected
by sample coloration, with an interchangeable electrochemical sensor
for the simultaneous detection of Tf and Tf-bound iron. Both modules
are interconnected through microfluidic channels whose flow is regulated
by a cylindrical rotary valve. The analytical workflow enables magnetic
bead-based direct Tf immunocapture and simultaneous electrochemical
detection of Tf and Tf-bound iron via square wave voltammetry, allowing
TSAT assessment within 60 min using only 50 μL of sample. Validation
with certified reference materials demonstrated excellent accuracy
(E
r ≤ 5%) and precision (RSD ≤
4%). Application to human serum from ischemic stroke patients showed
strong correlation (r = 0.87) and agreement (slope
0.9 ± 0.3; intercept 6 ± 10; p < 0.05)
with the urea-PAGE reference method, which typically requires up to
18 h. Overall, the 3D-EMD constitutes an elegant, fully integrated
dual-functionality platform that seamlessly combines customizable
sample preparation with online electrochemical detection in a single
device. This configuration enables direct serum analysis and supports
clinical decision-making in time-critical conditions. The device shows
strong potential as a rapid point-of-care testing
candidate for ischemic stroke and as a next-generation platform for
broader clinical diagnostics.