Research advances in the fabrication of biosafety and functional leather: A way-forward for effective management of COVID-19 outbreak

Abstract

With the recent events following the pandemic COVID-19, global awareness about the use of biosafety materials has been in raise. Leather industry being a major commodity-driven sector, its role in addressing the issues concerning the safe use of leather products has become inevitable for the sustainability of the industry. A significant number of researches have been conducted to fabricate bio-safe leather by incorporating different types of antimicrobial agents during leather manufacturing. Besides, the increasing diversity in the development of synthetic materials and the impact of COVID-19 outbreak on automotive industry may create more demand from customers for incorporating different functionalities in leather without losing its inherent properties. Some of the key functionalities discussed include resistance to microbial growth, self-cleaning through superhydrophobicity and photocatalysis, thermal regulation, flame retardance and scented leather. This review focusses on the fabrication of such advanced functional leather materials over the past decade with special emphasis on antimicrobial leather. Some of the key factors elaborated in the review include the state of art approaches for the preparation of functional materials, mode of incorporation of the same into the leather matrix, the mechanism behind with a perspective on the challenges involved in fabrication for real-world applications. A major outcome of this review is that even though several kinds of cutting edge researches are happening in the field of leather manufacturing, most of them were not validated for its practical applicability and sustainability of the proposed solution. This could be majorly attributed to the cost involved in fabrication of such materials, which forms a crucial factor when it comes to a mass production industry such as leather. Also, the researchers should concentrate on the toxicity of the fabricated materials which can impede the process of adopting such emerging and need of the hour technologies in the near future. Knowledge obtained from this review on fabrication of bio-safety leather against bacteria, mold and fungi would help further to integrate the antiviral property into the same which is a global need. Also, fabrication of functionalized leather would open new avenues for leather manufactures to venture into the development of advanced leather products such as flexible electronics, radiation shielding and fire fighting garments etc.

Keywords: Antimicrobial leather; Bio-safety; COVID-19; Functional materials; Leather.

Graphical abstract

Fig. 1

List of various functional properties incorporated into the leather matrix over past decade.

Fig. 2

Microbial growth observed on leather products at a shopping mall located in Malaysia during COVID-19 lockdown period.

Fig. 3

Graphical illustration for the fabrication of antimicrobial leather.

Fig. 4

Proposed mechanism of antimicrobial activity by BP and RB (Hong and Sun, 2010).

Fig. 5

Proposed mechanism on antimicrobial activity of the coating due to biocide release by urease enzyme (Xu et al., 2013).

Fig. 6

Visualization of fungal growth on (a) polyacrylate and (b) ZnO nanocomposite treated leather (Liu et al., 2014).

Fig. 7

(Left) Graphical representation showing the formation of ZnO microstructures of different morphology in a varied solvent system. (right) Images showing inhibition against Aspergillus flavus (a) without treatment and (b) treated by hollow columnar-like ZnO; Images sowing inhibition against Aspergillus flavus for leather matrix finished by (c) polyacrylate emulsion and (d) polyacrylate/hollow columnar-like ZnO composite emulsion (Bao et al., 2017).

Fig. 8

Synthetic route for the preparation of PEGylated chitosan (Luo et al., 2016).

Fig. 9

ZOI recorded using leather loaded with (a,e) nothing as control, (b,f) CS, (c,g) PEG–CS–4%, and (d,h) PEG–CS–8% (Luo et al., 2016).

Fig. 10

(1) ZOI of leather samples coated with water (a and e) as blank control, CS (b and f), PEG-CS (c and g) and PEG-CS@AgNPs, cultured with E. coli or S. aureus (2) Morphology of E. coli (A) and S. aureus (B) cells growing on the leather surface coated with PEG-CS@AgNPs after 24 h incubation and the red arrows indicate lesions and holes on the cell membrane after contact with PEG-g-CS@AgNPs coating (3) Proposed method of multi-functional antimicrobial mechanism by PEG–CS–AgNPs (Liu et al., 2017).

Fig. 11

Proposed mode of interaction and antimicrobial efficacy of (a) chrome tanned leather retanned with GA@AgNPs (Liu et al., 2018). (b) chrome tanned leather coated with GA@AgNPs (Xia et al., 2019).

Fig. 12

(a) Schematic illustration for the layered deposition of antimicrobial agents with subsequent crosslinking (b and c) Proposed mode of antimicrobial mechanism by leather treated with chitosan and crosslinked CS/GA@AgNPs (d) ZOI of leather samples against S. aureus (Xiang et al., 2018).

Fig. 13

Schematic illustration of fragrance release from vanillin treated fabrics (Fan et al., 2018).

Fig. 14

Proposed approach towards creating superhydrophobic surface using silica nano particles (Ma et al., 2015).

Fig. 15

[Top left] Schematic representation of synthesis of superhydrophobic SWCNTs. [Top right] FTIR spectra of (a) SWCNT-n(OH) (b) azide-functionalized SWCNTs and (c) copolymer of SWCNTs (Arrow marks indicating the disappearance of azide functional group after polymersiation reaction) [Bottom left] Contact angle of water droplet on glass surface after drop casting and drying with (a) THF (b) Pristine SWCNTs (c) SWCNT-n(OH) (d) click copolymer of SWCNTs. [Bottom right] XPS spectra of copolymer of SWCNTs (Krishnamurthy et al., 2017).

Fig. 16

Visual examination of MB spot and ball pen ink line degradation on leather surface treated with Fe–N–TiO₂ (Top) and untreated control leather (Bottom), under Visible light irradiation (Petica et al., 2015).

Fig. 17

Hierarchical ordering of collagen (Wang et al., 2020).

Fig. 18

Thermal images of people's hand covered by the leather/SiO₂, pristine leather and leather-SiO₂ (Top to bottom) (blue to red transition refers to cool to hot) (Wang et al., 2019).

Fig. 19

Infrared thermal camera images of coated leather without PCMs (DX side) and coated leather with 40 wt% Ty65 (SX side) (Izzo Renzi et al., 2010).

Fig. 20

Synthetic procedure for the preparation of (a) PFR, (b) NPIFR and (c) NPFR (Duan et al., 2019).

Fig. 21

Schematic representation of the flame retardance mechanism by MZBMSO-sLDH nanocomposites (Lyu et al., 2019).

Fig. 22

Plausible interaction mechanisms of the MZBMSO and MZBMSO/OSA-LDH with collagen (Lyu et al., 2020).