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Green Reports
Research Article
Biomass Derived Keratin Composites and its Applications: A Review
Mayakrishnan Gopiraman,*a BEN HALIMA Nihed,b Ill-Min-Chung*a
aDepartment of Applied Bioscience, College of Life and Environmental Science, Konkuk University, 120 Neungdong-ro, Gwangijin-gu, Seoul (05029), South Korea.
bNational Engineering School of Sfax, Biological Engineering Department, University of Sfax, Sfax 3029, Tunisia
*Corresponding author E-mail address: illminchung@gmail.com (Ill-Min-Chung); gopiraman@konkuk.ac.kr (Gopiraman)
Abstract: Keratin protein is a versatile biopolymer having exceptional properties such as remarkable biocompatibility and biodegradability for various applications. Keratin possesses many distinct advantages over conventional biomolecules, due to its intrinsic cellular recognition, high sulfur content and propensity for self-assembly. Typically, kertain has been extracted from various biowaste sources including hair, fingernails, shells, horn, hooves, toenails, beaks, feathers and claws. So far, several methods for the extraction of keratin protein have been developed. The keratin proteins can be improved and modified in many forms such as gels, films, beads, nanoparticles, and microparticles. After modification, its uses in various industries such as pharmaceuticals, cosmetic, food science and green chemistry is exceptional. Particularly, in recent years, research on the production of keratin has greatly increased due to the abundance of potential applications. The research and development of keratin protein are still continues to expand. The most important driving forces for this development are the increasing demand of this cost-effective keratin material. Hence, in this review, we mainly focus on the applications of keratin nanocomposites. In addition, part of this review focuses on the preparation methodologies and characterization techniques of the extracted keratin and keratin-based nanocomposites.
Keywords: Biomass; Keratin composites; Textiles; Catalysis; Biomedical; Energy; Agricultural
Publication details: Received: 15th February 2020; Revised: 14th April 2020; Accepted: 21st April 2020; Published: 29th April 2020
1. Introduction
A broad category of insoluble proteins that associate as intermediate filaments (IFs), a cytoskeletal element with 8–10 nm diameter, were being referred to the term “keratin”.[1] Fig. 1 diagram showing inter- and intra-molecular bonding in keratin. Various chemical bonds (e.g. hydrogen, ionic and disulfide bonds) which result in increased strength and stability of the protein, determine the structure of the keratin. Based on structure, function and regulation, keratin is categorized into two distinct groups namely hard and soft.[2,3] Hard keratins form ordered arrays of intermediate filaments embedded in a matrix of cystine rich proteins and contribute to the tough structure of epidermal appendages. However, soft keratins often form loosely-packed bundles of cytoplasmic intermediate filaments and typically contain less sulphur.[4,5] Kertain can be extracted from various biowaste such as hair, fingernails, shells, horn, hooves, toenails, beaks, feathers and claws.[6-8] Fig. 2 shows the biowaste sources of kertain. The extracted keratin materials have been utilized for various applications such as catalysis, energy, biomedical and textile applications. In fact, biomass derived keratin structural morphology is highly unique and it is nearly impossible to mimic the structure.[9] For instance, PbS nanocrystals were formed within the keratin rich human hair-matrix during blacking.[10] They found that the shape and distribution of nanoparticles are controllable. Walter et al.,[11] utilized keratin rich human hair fiber as a reactor/medium for the controlled synthesis of fluorescent Ag nanoparticles. Not only for the nanoparticles carrier, the keratin was used for wide range of applications and it has an ability to replace an expensive biomaterials. Nanocellulose, wool-keratine, chitosan, natural pumice, mycelial, gram negative bacteria, and gram positive bacteria are some of the green materials reported to date.[12] Keratin may be used instead of the above mentions biomaterials due to its cost-effectiveness. In spite of these advantages and availability, the biomass derived keratin is less investigated for its potential applications. However, particularly, in recent years, research on the production of keratin has greatly increased due to the abundance of potential applications. The research and development of keratin protein are still continues to expand. The most important driving forces for this development are the increasing demand of this cost-effective keratin material. Hence, in this review, we mainly focus on the preparation methodologies of keratin nanoparticles and its usefulness. In addition, part of this review focuses on the fabrication methods and applications of keratin-based nanocomposites.
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