Contents lists available at ScienceDirect European Polymer Journal journal homepage: www.elsevier.com/locate/europolj Full Length Article Development of chromatic biosensor for quick bacterial detection based on polyvinyl butyrate-polydiacetylene nonwoven fiber composites Pablo Vidal a , Misael Martinez b , Carlos Hernandez b , Ananta Raj Adhikari c , Yuanbing Mao d , Luis Materon e , Karen Lozano b, ⁎ a Math and Science Academy, The University of Texas Rio Grande Valley, Edinburg, TX 78539, United States b Mechanical Engineering Department, The University of Texas Rio Grande Valley, Edinburg, TX 78539, United States c Physics Department, State University of New York, Potsdam, NY 13676, United States d Chemistry Department, The University of Texas Rio Grande Valley, Edinburg, TX 78539, United States e Biology Department, The University of Texas Rio Grande Valley, Edinburg, TX 78539, United States ARTICLE INFO Keywords: Chromic biosensor Smart polymer scaffold Bacteria Polyvinyl butyrate Polydiacetylene ABSTRACT Infections are caused by a wide variety of bacterial pathogens. The severity of the infection can range from imperceptible to potentially fatal. Early bacterial detection is vital to avoid complications. Smart polymer scaffolds have shown promising in biomedical applications. In this work, we prepared polyvinyl butyrate (PVB)/ diacetylene (DA) nonwoven fine fibers with diameters ranging from 1.4 to 1.9 μm using the Forcespinning® technique. PVB/DA fibers were subjected to ultraviolet light to polymerize the diacetylene. Polymerization process was analyzed through photo-calorimetry studies; the total heat of cure was quantified to be 4650 J/g. Thermogravimetric analysis showed increased thermal stability of PVB-PDA compared to PVB by about 50 °C. The bio-sensing response to gram positive (Staphylococcus aureus, Micrococcus luteus, and Corynebacterium amycolatum) and gram negative (Escherichia coli and Pseudomonas aeruginosa) bacteria was investigated. Plates with varying concentration of bacteria were prepared ranging from 10 7 to 1 colony forming units (cfu) per plate. The sensing ability of the chromatic biosensor was observed as soon as 30 min after placing the membranes in the bacteria at 37 °C. Samples exposed to Staphylococcus aureus, Micrococcus luteus, and Escherichia coli responded to the plates with the minimum number of bacteria (6, 3, and 7 cfu/plate, respectively) while the sample exposed to Corynebacterium amycolatum needed more than 6000 cfu/plate to respond within the first 30 min and at all levels within 24 h. The samples exposed to Pseudomonas aeruginosa did not respond within 30 min, a response was observed at 48 h. These flexible membranes show promising potential to be used as scaffolds/bandages to alert patients of potential infections caused by microbial attack before the individual appears symptomatic. 1. Introduction Burns are one of the major causes of injury and death worldwide resulting in more than 180,000 deaths/year. Burn care costs add up to more than $10.4 billion per year only in the United States [1]. A major factor relates to common complications from pathogenic infections caused by the involvement of microorganisms in the wounded site. Microorganisms can enter the site through different routes such as di- rect contact, airborne dispersal, and self-contamination. Early detection of pathogenic bacteria in food, water, or in public places including hospitals is an imperative need. A wide number of studies have focused on developing different point-of-care (POC) technologies to monitor development and healing process of wounds and burns [2–4]. Evaluation of wound pH is one of the well-known methods to indicate bacterial growth in the wound exudate [5,6]. Other approaches include conventional methods (e.g., polymerase chain reaction (PCR), culture and colony counting methods) and indicator papers that could only be used by professionals in controlled environments [2,7]. These approaches to evaluate wounds/burns are time consuming, require expensive instrumentation, and qualified professionals. To the authors’ knowledge, there are no any rapid and cost effective methods for early detection of pathogens. This study focuses on the development of a chromatic flexible bio- sensor for early bacteria detection. The scaffold utilizes polydiacetylene (PDA) as the sensing system. PDA is a conducting polymer with unique optical and fluorescence properties [8–10]. Numerous studies had been https://doi.org/10.1016/j.eurpolymj.2019.109284 Received 10 January 2019; Received in revised form 30 July 2019; Accepted 2 October 2019 ⁎ Corresponding author. E-mail address: Karen.lozano@utrgv.edu (K. Lozano). European Polymer Journal 121 (2019) 109284 Available online 05 October 2019 0014-3057/ © 2019 Elsevier Ltd. All rights reserved. T