4D-printed shape-programmable [H⁺]-responsive needles for determination of urea

Area of Science:

• * Materials Science and Engineering
• * Analytical Chemistry
• * Biomedical Engineering

Background:

• * Four-dimensional printing (4DP) offers advanced fabrication of stimuli-responsive devices with complex geometries and functions.
• * The shape-programming capabilities of 4DP devices are crucial for their analytical performance but remain underexplored.
• * Stimuli-responsive materials enable devices to change shape in response to environmental cues, ideal for sensing applications.

Purpose of the Study:

• * To investigate the impact of shape-programming modes on the analytical performance of 4DP stimuli-responsive devices.
• * To develop and optimize a 4DP-based sensing device for quantitative urea determination.
• * To demonstrate the applicability of 4DP in creating advanced chemical sensing platforms.

Main Methods:

• * Fabrication of bending, helixing, and twisting needles using digital light processing 3D printing with acrylate-based resins and 2-carboxyethyl acrylate (CEA).
• * Utilizing the pH-dependent swelling of CEA-incorporated parts for shape programming triggered by changes in hydrogen ion concentration ([H+]).
• * Coupling the shape programming with urease-mediated urea hydrolysis for urea quantification based on shape-programming angles.

Main Results:

• * The [H+]-dependent swelling of CEA-incorporated 4DP needles enabled shape programming.
• * Urea determination was achieved by correlating shape-programming angles with urea concentration via urease reaction.
• * Helixing needles demonstrated optimal analytical performance with a detection limit of 0.9 μM for urea.
• * The method's reliability was validated in complex biological matrices like human urine, sweat, serum, and plasma.

Conclusions:

• * Optimizing shape-programming modes is critical for enhancing the analytical performance of 4DP stimuli-responsive sensing devices.
• * 4DP technology provides a powerful platform for fabricating advanced, stimuli-responsive sensors for chemical analysis.
• * The developed helixing needle sensor offers a sensitive and reliable method for urea quantification in various biological samples.