One-Pot Extraction of Bioresources from Human Hair via a Zero-Waste Green Route

Abstract

In recent years, the extraction of bioresources from biowaste via green chemistry and their utilization for the production of materials has gained global momentum due to growing awareness of the concepts of sustainability. Herein, we report a benign process using an ionic liquid (IL), 1-butyl-3-methylimidazolium chloride ([BMIM]Cl), for the simultaneous extraction of keratin and melanin from human hair. Chemical characterization, secondary structure studies, and thermal analysis of the regenerated protein were performed thoroughly. Hemolytic potential assays demonstrated hemocompatibility of the keratin, and thus, it can be used in blood-contacting biomaterials such as sealants, catheters, hemostats, tissue engineering scaffolds, and so on. Scanning electron microscopy showed retention of the ellipsoidal morphology of melanin after the extraction procedure. The pigment demonstrated the ability to reduce 2,2-diphenyl-1-picrylhydrazyl indicative of its free-radical scavenging activity. Notably, the IL could be recovered and recycled from the dialysis remains which also exhibited conductivity and can be potentially used for bioelectronics. Altogether, this work investigates an extraction process of biopolymers using green chemistry from abundantly available biowaste for the production of biomaterials and does not produce any noxious waste matter.

Melanin Upcycling: Creation of Polymeric Materials from Melanin Decomposition Products

“…More importantly, the method described in this paper shows that oligomers of carboxylic acid-containing pyrrole derivatives can be obtained as the main decomposition products from either natural or artificial melanin. This means that other natural products, such as animal hair and insect exoskeletons, could be used as melanin sources instead of cuttlefish ink. − , Additionally, using melanin sources produced through bioprocesses through melanogenic microbes, including fungi and bacteria, is a useful option. − It could also lead to the recycling of PDA, the artificial melanin used in many studies. − While the recovery of AMDP and NMDP from AM and NM was approximately 20 and 18 wt %, respectively, under the conditions of the present experiment, a more efficient recovery process is currently under investigation. Just as research on cellulosic biomass has advanced because cellulose can be extracted from various underutilized plants, it is hoped that the use of melanin as a biomass will also increase.…”

“…This means that other natural products, such as animal hair and insect exoskeletons, could be used as melanin sources instead of cuttlefish ink. [22][23][24]106 Additionally, using melanin sources produced through bioprocesses through melanogenic microbes, including fungi and bacteria, is a useful option. 17−21 It could also lead to the recycling of PDA, the artificial melanin used in many studies.…”

“…From a resource perspective, the melanin concentrated in the ink sacs of cuttlefish and squid is easily recoverable natural melanin. , The catch of squid and octopus has been increasing yearly and hovering around 3 million tons for the past few years . Recent studies have also reported melanin production by bioprocesses using melanin-producing microorganisms such as fungi and bacteria − and efficient methods for extracting melanin from animal hair. − Thus, renewable melanin obtained from diverse biological resources can be regarded as a sustainable biomass resource. Traditionally, cuttlefish and squid inks have been chiefly discarded except for use as food products and ink for packaging containers. , In recent years, however, inspired by the excellent photofunctional properties of melanin, there has been a growing trend to create functional materials such as photothermal therapy, UV shielding, dye-sensitized solar cells, energy storage, optical, and organic bioelectronic materials by using natural melanin as is or in combination with other materials. ,− On the other hand, to our knowledge, an attempt has yet to be made to decompose melanin into a useful resource.…”