Development of a simple colorimetric sensor for bacteria detection

¹ Department of Industrial Chemistry, Faculty of Applied Science, King Mongkut’s University of Technology North Bangkok, 10800 Bangkok, Thailand
² The Petroleum and Petrochemical College, Chulalongkorn University, 10330 Pathumwan, Bangkok, Thailand
³ The Center of Excellence on Petrochemical and Materials Technology, Chulalongkorn University, 10330 Pathumwan, Bangkok, Thailand

^* Corresponding author: saowapa.t@sci.kmutnb.ac.th

Abstract

Wound care is vital to prevent infections and inflammation that can lead to chronic wounds. This study developed a novel chitosan-based wound dressing incorporated with purple corn (Zea mays L.) extract as a colorimetric sensor for detecting bacterial infections. The dressings were prepared using 1.5% w/v chitosan, 2 mL glycerol, and varying amounts of purple corn extract (5–20 g). The formulation containing 20 g extract showed the highest anthocyanin content (177.10 ± 1.77 mg/L) and desirable mechanical properties, including a tensile strength of 0.26 ± 0.04 MPa, elongation at break of 23.75 ± 1.77%, and Young’s modulus of 25.33 ± 1.96 MPa. SEM analysis revealed a smooth surface with uniform extract distribution. The water vapor transmission rate (734 ± 18 g/m²/day) indicated suitable moisture permeability for wound healing. The dressing exhibited clear pH-dependent color changes orange (pH 5.0), purple-brown (pH 7.4), and dark brown (pH 9.0) enabling visual detection of infection-related pH shifts. Additionally, it showed strong antibacterial activity. These results demonstrate that purple corn extract-infused chitosan dressing is a promising smart wound care material with dual functions: pH-responsive sensing and antibacterial protection.