Biodegradable antimicrobial films based on poly(lactic acid) matrices and active azo compounds Simona Concilio, 1 Pio Iannelli, 2 Lucia Sessa, 1 Rita Olivieri, 1 Amalia Porta, 2 Felice De Santis, 1 Roberto Pantani, 1 Stefano Piotto 2 1 Department of Industrial Engineering, University of Salerno, I-84084 Fisciano (Salerno), Italy 2 Department of Pharmacy, University of Salerno, I-84084 Fisciano (Salerno), Italy Correspondence to: S. Concilio (E - mail: sconcilio@unisa.it) ABSTRACT: Using solvent casting and melt compounding methods, we realized antibacterial and antifungal poly(lactic acid)-based films by introducing different percentages of antimicrobial azo dyes into polymer matrices. Concentration up to 0.01% (w/w) of azo compounds permitted the preparation of antimicrobial and transparent films. The thin films retained the properties of the pure PLA matrices, such as glass transition temperature, flexibility, and amorphous nature. The films exhibited antimicrobial activity and the capability to inhibit biofilms formation of Staphylococcus aureus and Candida albicans. Spectrophotometric investigation of azo com- pounds release from the polymer matrices confirmed that the materials might have applications in fields where an intrinsic antimi- crobial ability of the material is required, such as biomedical tools, biodegradable antibacterial coatings, and films for active packaging. V C 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42357. KEYWORDS: biomaterials; biomedical applications; coatings; composites; films Received 20 January 2015; accepted 13 April 2015 DOI: 10.1002/app.42357 INTRODUCTION Infections by pathogenic microorganisms are of great concern for the realization of medical devices as well as food packaging materials. 1,2 The appearance of microorganisms resistant to the most common drugs increases this concern. Bacterial infections are frequently associated with the use of medical devices, therefore it is essential to develop new materi- als with antimicrobial activity to solve the problem of contami- nation by microorganisms. 3,4 In an effort to address this problem, commercial antibacterial agents have been incorpo- rated in numerous types of materials for medical devices. 5,6 Sev- eral antimicrobial agents have been introduced into polymers; the most common antimicrobial agents used in polymer films are triclosan, chlorhexidine, tetracycline and derivatives, benzo- phenon, and rifampicin. 1 Our strategy is to insert new synthetic antimicrobial azo com- pounds into polymer materials with excellent biocompatibility. Recently we synthesized a new class of antimicrobial com- pounds with azobenzene structure. 7,8 These compounds showed a strong activity against Gram1 bacteria and fungi. The ones having the strongest bactericidal activity and the ability to inhibit the biofilm formation have already been selected for incorporation into commercial polyolefin matrices, in order to produce composites with low production cost, good processabil- ity, and antimicrobial potential. 9 In this work we consider the insertion of three of these mole- cules (namely A3, A4, and A5) in biodegradable polymers, addressing chemical issues, microbiocidal activity, stability, and processability of the final material. We focused our attention on poly(lactic acid) or polylactide (PLA) as a representative example of biodegradable polymers, suitable for the realization of thin films. 10–12 PLA is a thermoplastic aliphatic polyester obtained by ring- opening polymerization of lactide derived from the fermenta- tion of sugar feed stocks such as corn. Recent development of a continuous process of production of this resin has lowered the price of PLA to the point where it is now competitive with other degradable polymers and potentially competitive with petroleum derived plastics. 13 PLA has found applications in the medical and packaging fields because of its promising mechanical properties, its potential for biodegradability and biocompatibility. 14–18 Additional Supporting Information may be found in the online version of this article. V C 2015 Wiley Periodicals, Inc. WWW.MATERIALSVIEWS.COM J. APPL. POLYM. SCI. 2015, DOI: 10.1002/APP.42357 42357 (1 of 8)