title: Supercritical CO2 foaming of thermoplastic materials derived from maize: proof-of-concept use in mammalian cell culture applications.
abstract: BACKGROUND
  Foams are high porosity and low density materials. In nature, they are a common architecture. Some of their relevant technological applications include heat and sound insulation, lightweight materials, and tissue engineering scaffolds. Foams derived from natural polymers are particularly attractive for tissue culture due to their biodegradability and bio-compatibility. Here, the foaming potential of an extensive list of materials was assayed, including slabs elaborated from whole flour, the starch component only, or the protein fraction only of maize seeds.
  
  
  RESULTS
  We used supercritical CO2 to produce foams from thermoplasticized maize derived materials. Polyethylene-glycol, sorbitol/glycerol, or urea/formamide were used as plasticizers. We report expansion ratios, porosities, average pore sizes, pore morphologies, and pore size distributions for these materials. High porosity foams were obtained from zein thermoplasticized with polyethylene glycol, and from starch thermoplasticized with urea/formamide. Zein foams had a higher porosity than starch foams (88% and 85%, respectively) and a narrower and more evenly distributed pore size. Starch foams exhibited a wider span of pore sizes and a larger average pore size than zein (208.84 vs. 55.43 μm2, respectively). Proof-of-concept cell culture experiments confirmed that mouse fibroblasts (NIH 3T3) and two different prostate cancer cell lines (22RV1, DU145) attached to and proliferated on zein foams.
  
  
  CONCLUSIONS
  We conducted screening and proof-of-concept experiments on the fabrication of foams from cereal-based bioplastics. We propose that a key indicator of foamability is the strain at break of the materials to be foamed (as calculated from stress vs. strain rate curves). Zein foams exhibit attractive properties (average pore size, pore size distribution, and porosity) for cell culture applications; we were able to establish and sustain mammalian cell cultures on zein foams for extended time periods.
authors: Centro de Biotecnología-FEMSA, Tecnológico de Monterrey, Monterrey, Nuevo León, México; Harvard-MIT Helath Sciences and Technology, Brigham and Women's Hospital, Cambridge, Massachusetts, United States of America.
authors: Grissel
authors: G
authors: Trujillo-de Santiago
authors: Centro de Biotecnología-FEMSA, Tecnológico de Monterrey, Monterrey, Nuevo León, México.
authors: Cynthia Guadalupe
authors: CG
authors: Portales-Cabrera
authors: Centro de Biotecnología-FEMSA, Tecnológico de Monterrey, Monterrey, Nuevo León, México.
authors: Roberto
authors: R
authors: Portillo-Lara
authors: Centro de Biotecnología-FEMSA, Tecnológico de Monterrey, Monterrey, Nuevo León, México.
authors: Diana
authors: D
authors: Araiz-Hernández
authors: Institute of Polymers, Composites and Biomaterials, Consiglio Nazionale delle Ricerche, Naples, Italy.
authors: Maria Cristina
authors: MC
authors: Del Barone
authors: Centro de Innovación en Diseño y Tecnología, Tecnológico de Monterrey, Monterrey, Nuevo León, México.
authors: Erika
authors: E
authors: García-López
authors: Centro de Biotecnología-FEMSA, Tecnológico de Monterrey, Monterrey, Nuevo León, México.
authors: Cecilia
authors: C
authors: Rojas-de Gante
authors: Departamento de Producción Animal, Universidad Autónoma Agraria Antonio Narro, Torreón, Coahuila, México.
authors: María
authors: M
authors: de Los Angeles De Santiago-Miramontes
authors: Unidad de Bio-imagen/Microscopía, Universidad Autónoma de Nuevo León, Monterrey, Nuevo León, México.
authors: Juan Carlos
authors: JC
authors: Segoviano-Ramírez
authors: Centro de Biotecnología-FEMSA, Tecnológico de Monterrey, Monterrey, Nuevo León, México.
authors: Silverio
authors: S
authors: García-Lara
authors: Centro de Innovación en Diseño y Tecnología, Tecnológico de Monterrey, Monterrey, Nuevo León, México.
authors: Ciro Ángel
authors: CÁ
authors: Rodríguez-González
authors: Centro de Biotecnología-FEMSA, Tecnológico de Monterrey, Monterrey, Nuevo León, México; Harvard-MIT Helath Sciences and Technology, Brigham and Women's Hospital, Cambridge, Massachusetts, United States of America.
authors: Mario Moisés
authors: MM
authors: Alvarez
authors: Dipartimento di Ingegneria Chimica, dei Materiali e della Produzione Industriale, University of Naples Federico II, Naples, Italy.
authors: Ernesto
authors: E
authors: Di Maio
authors: Institute of Polymers, Composites and Biomaterials, Consiglio Nazionale delle Ricerche, Naples, Italy.
authors: Salvatore
authors: S
authors: Iannace
mesh_terms: D000818:Animals; D001672:Biocompatible Materials; D002245:Carbon Dioxide; D018929:Cell Culture Techniques; D002460:Cell Line; D006801:Humans; D008422:Materials Testing; D051379:Mice; D016062:Porosity; D013696:Temperature; D003313:Zea mays; D015028:Zein
chemical_list: D001672:Biocompatible Materials; D002245:Carbon Dioxide; D015028:Zein