A strip-and-read gelatin-coated paper-based analytical device for the extraction and colorimetric determination of curcumin in real food and pharmaceutical matrices.

BACKGROUND: Curcumin, a bioactive nutraceutical widely used in food, cosmetics, and pharmaceuticals, exhibits diverse pharmacological properties but excessive intake can pose health risks, necessitating reliable quantification in complex matrices. Traditional analytical techniques and existing sample extraction methods provide excellent sensitivity but are hindered by their reliance on expensive instrumentation, hazardous organic solvents, labor-intensive workflows, and inability to perform decentralized, on-site testing. These challenges highlight the need for a low-cost, rapid, portable, and eco-friendly tool capable of simultaneous extraction and quantification of curcumin. To address this, we developed a gelatin-coated paper-based analytical device (GPAD) that combines cellulose support with an active gelatin solid-phase adsorbent layer for green extraction and smartphone colorimetric detection.

RESULTS: The GPAD was fabricated by coating cellulose filter paper with gelatin, yielding enhanced sorptive capacity and surface functionality. Coating uniformity was confirmed by water contact angle, ninhydrin test, ATR-FTIR, SEM, and EDX analyses. Mechanistic studies revealed curcumin binding via hydrophobic interactions and hydrogen bonding. Adsorption produced a distinct yellow color quantified by smartphone colorimetric detection. The method showed excellent performance with linearity (0.4-40 μg/mL), accuracy (100% ± 2%), precision (%RSD <2%), and a limit of detection of 0.07 μg/mL. Greenness, practicality, and innovation were confirmed using AGREE, BAGI, and VIGI tools. The GPAD was successfully applied to pharmaceutical capsules and food matrices including mustard, custard, and peanut chocolate candy.

SIGNIFICANCE AND NOVELTY: This sustainable and biocompatible platform enables simultaneous extraction and quantification of curcumin with minimal reagent use and no reliance on sophisticated instrumentation. By integrating gelatin's sorptive properties with paper-based portability and smartphone detection, GPAD offers a rapid, low-cost, eco-friendly solution aligned with white analytical chemistry, with strong potential for point-of-need curcumin monitoring.