Fabrication of paper-based analytical devices optimized by central composite design

Area of Science:

• Analytical Chemistry
• Materials Science
• Chemical Engineering

Background:

• Paper-based analytical devices (PADs) offer a low-cost, portable platform for chemical analysis.
• Optimization of PADs is crucial for enhancing assay sensitivity and reliability.
• Isoniazid determination is important for tuberculosis treatment monitoring.

Purpose of the Study:

• To optimize an isoniazid assay on a single-area inkjet-printed paper-based analytical device (PAD).
• To evaluate the impact of device geometry and reagent concentrations on assay performance.
• To establish a sensitive and reliable method for isoniazid quantification.

Main Methods:

• Design of Experiments (DOE) approach, specifically a central composite design, was employed.
• Key factors optimized included printed dimensions (length, width) and sampling volume.
• Assay reagents (polyvinyl alcohol, ammonium hydroxide, silver nitrate) were deposited using thermal inkjet printing.

Main Results:

• The optimized device demonstrated a linear calibration curve for isoniazid detection in the range of 0.03-10 mmol L-1.
• A low relative standard deviation of 3.4% was achieved for isoniazid determination.
• The assay mechanism involves the formation of yellow silver nanoparticles (AgNPs) for colorimetric detection.

Conclusions:

• The optimized inkjet-printed PAD provides an efficient method for isoniazid assay.
• The developed device is suitable for determining isoniazid in pharmaceutical preparations.
• This work highlights the potential of DOE for optimizing PADs in analytical applications.