key: cord-0787371-uruieqv0
authors: Patil, Nikhil Avinash; Gore, Prakash Macchindra; Prakash, Niranjana Jaya; Govindaraj, Premika; Yadav, Ramdayal; Verma, Vivek; Shanmugarajan, Dhivya; Patil, Shivanand; Kore, Abhay; Kandasubramanian, Balasubramanian
title: Needleless electrospun phytochemicals encapsulated nanofibre based 3-ply biodegradable mask for combating COVID-19 pandemic
date: 2021-02-26
journal: Chem Eng J
DOI: 10.1016/j.cej.2021.129152
sha: 690bcfff2f63b8eb1ed7f76efe5780dcad4af977
doc_id: 787371
cord_uid: uruieqv0

The emergence of COVID-19 pandemic has severely affected human health and world economies. According to WHO guidelines, continuous use of face mask is mandatory for personal protection for restricting the spread of bacteria and virus. Here, we report a 3-ply cotton-PLA-cotton layered biodegradable face-mask containing encapsulated phytochemicals in the inner-filtration layer. The nano-fibrous PLA filtration layer was fabricated using needleless electrospinning of PLA & phytochemical-based herbal-extracts. This 3-layred face mask exhibits enhanced air permeability with a differential pressure of 35.78 Pa/cm(2) and superior bacterial filtration efficiency of 97.9% compared to conventional face masks. Close-packed mesh structure of the nano-fibrous mat results in effective adsorption of particulate matter, aerosol particles, and bacterial targets deep inside the filtration layer. The outer hydrophobic layer of mask exhibited effective blood splash resistance up to a distance of 30 cm, ensuring its utilization for medical practices. Computational analysis of constituent phytochemicals using the LibDock algorithm predicted inhibitory activity of chemicals against the protein structured bacterial sites. The computational analysis projected superior performance of phytochemicals considering the presence of stearic acid, oleic acid, linoleic acid, and Arachidic acid exhibiting structural complementarity to inhibit targeted bacterial interface. Natural cotton fibers and PLA bio-polymer demonstrated promising biodegradable characteristics in the presence of in-house cow-dung based biodegradation slurry. Addition of jaggery to the slurry elevated the biodegradation performance, resulting in increment of change of weight from 07% to 12%. The improved performance was attributed to the increased sucrose content in biodegradation slurry, elevating the bacterial growth in the slurry. An innovative face mask has shown promising results for utilization in day-to-day life and medical frontline workers, considering the post-pandemic environmental impacts.

Outbreak of the infectious SARS-CoV2 disease has drastically affected health of the global population, causing long time effects on respiratory systems of the human body [1] . According to the World Health Organization, spread of virus can be controlled using personal protective equipment such as face masks, protective suits, and face shields [2] . Global outbreak of the infectious virus has emerged with the need of an effective face mask for containing the spread of infectious aerosol particles, since most infectious respiratory disease causing viruses such as Influenza A are majorly transmitted through aerosol particles [3] . To restrain the spread of virus, conventionally available disposable non-woven surgical face mask and respirators were recommended for respiratory protection [4] . However, working principle of the mask was focused on physical blocking of pathogens in the air. Live infectious pathogens on the surface of mask are primary source for contamination during the reuse or disposal of PPE [5] . Alternatively, the cloth mask is significantly advantageous for constraining the spread of virus due to better reusability and filtration of nano-scale aerosol particles in the air [6] . Among the conventional cloth masks, multiple layered face masks were recorded to showcase better results in restricting the spread of aerosol particles [7] .

Incorporation of the electrospun nano-fibrous layer in multi-layered face mask structure has resulted in showcasing ameliorated filtration capabilities of the face mask [8, 9] . Electrospun nano-fibrous mats have been crucial in capturing the tiny particulate matter with efficiencies of more than 99% [10] . The nano and micro structured membranes have showcased significant application in separation and purification technologies [11] . Fine fiber diameter of the electrospun nano-fiber facilitates increment in specific surface area of filter media, resulting in efficient filtration capabilities of the nano-fibrous layer [12, 13] . Further, the micro structured surface 4 morphology determines the filtration capabilities of the electrospun layer, whereas interfacial adhesion between the fibers facilitates formation of close-packed structure, which help in improving the filtration performance of the membranes [14, 15] . Surface porosity and chemically functionalized surface of the nano-fibrous membranes has crucial impacts on filtration capabilities of nano-membranes, facilitating the ameliorated performance for capturing micro-sized particulate matter [16] . While maintaining the high filtration efficiency, low-pressure drop across the filter media carries vast importance in determining breathability of face mask [17] . Many commercialized fibers such as glass fibers, cellulose fibers, and melt-blown fibers have been investigated for their filtration performance, but the presence of micro-fiber diameter limits the further filtration performance of those fibers [18] . The utilization of single-use disposable nonwoven face mask in filter media has resulted in the release of microplastics in the environment [19, 20] . These microfibers released in the water reservoirs affects aquatic life and humankind by accumulating used face masks into landfills, resulting in deterioration of the ecological system [21, 22] , also, the release of microfibers in the human body may propagate invasive pathogens in the body [23] . On the contrary, utilization of the cloth material based face masks have been significantly crucial for exhibiting adequate filtration efficiency and reusability of the face mask for daily use [24, 25] . Several bio-based materials are also reported to exhibit enhanced air filtration capacities, providing a balance between filtration capabilities and antimicrobial activity [26] .

In addition to the ameliorated performance of electrospun nano-fibrous layer, addition of immune-boosting chemicals has a significant role in controlling the effects of infectious viruses and bacteria [27] [28] [29] . The injection mode for immune-boosting drugs and vaccines is effective through inhalation, reducing the efforts of trained medical staff's and becoming significantly advantageous in resource-poor regions. Predominantly, herbal plants or spices' extracts have 5 potent effects against the activity of dreadful airborne viruses [30] [31] [32] . Xingjiang Xiong et al. have reported the biological activity of Chinese herbal extracts-based medicine, capable of combating the SARS-CoV-2 virus [33] . Glucocorticoids based drug treatment for SARS-CoV-2 have shown promising results by reducing the mechanical ventilation and mortality rate among COVID-19 patients compared to standard care protocol. Glucocorticoids were evident intervention for reducing the mechanical ventilation (31 fewer per 1000 patients, 47 fewer to 9 fewer, moderate certainty) and death rate (risk difference 37 fewer per 1000 patients, 95% credible interval 63 fewer to 11 fewer, moderate certainty) when compared with standard care [34] . Iveta Bartonkova et al. have demonstrated the activity of essential oils on glucocorticoid receptor; biological activities of essential oils were analyzed to have anti-microbial, anti-inflammatory, antihypertensive, and anti-fungal properties, enhancing the immunity of the human body against dreadful viruses [35] . The quantitative structure-toxicity relationship (QSTR) analysis of plantderived herbal oils are recorded to be non-toxic, biodegradable, no irritancy at a lower concentration, and non-mutagenic.

Wide usage of non-woven face mask for restraining the spread of COVID-19 pandemic has led to serious environmental impacts; resulting in increment of drastic effects on living ecological systems [36] . These environmental impacts encourage the research to develop an environment-friendly and biodegradable mask for combating infectious diseases [37] . The biodegradable fibers such as polylactic acid based electrospun nano-fiber layer have exhibited promising results for effective filtration of air and aerosol particles in the environment [38] . The nature-derived polymeric material has showcased microbial and enzymatic biodegradation studies as recorded in various investigations [39] [40] [41] [42] [43] [44] . The other cellulosic component of the 3-ply face mask has demonstrated excellent biodegradation characteristics of the material [45] . The 6 biodegradation slurry consisting of compost culture has shown encouraging results for degradation of cotton fabrics [46] . The immune-boosting herbal extracts present in the nano-fibrous PLA filtration layer have been reported to exhibit adequate biodegradability without affecting the environmental system [47] .

The current study is focused on the fabrication of cotton/PLA based biodegradable mask showcasing the antiviral, anti-bacterial, and breathable characteristics. The major experiments of the investigation are focused on -(1) Fabrication of 3-layered mask, whose upper and lower fabric being consisting of cotton, and the middle layer comprising of an electrospun nano-fibrous Poly to evaluate bacterial filtration efficiency, air permeability, and blood splash resistance, for determining the product's effectiveness among medical frontline workers and citizens for day-today use. The analysis of a mask's surface wettability has a crucial role in the reusability of a mask after multiple piles of washing. (5) Biodegradation characteristics of face masks are evaluated for analyzing the after effects of used face mask, in order to minimize the environmental impacts due to pandemic.

Poly-(lactic acid) (PLA) (FIBREEL, white colour, 1.75 mm diameter) was procured from Rever Industries, Nashik, India. Dichloromethane (99% pure) was procured from Thermo Fisher 7 Scientific India Pvt Ltd, which is utilized as a solvent for dissolving the PLA polymer. 100% cotton fabric material (thickness of 0.33mm, 150 GSM, warp and weft count of 20×20 respectively, ends and picks per inch of 56×56) was procured from the local fabric market. Azadirachta Indica has been extracted from Agri based neem seeds, procured from local farmers in Pune, India. The herbal extracts of Eucalyptus Citriodora were procured from Vishal Chemicals, Mumbai, India. A digital thickness meter gauge was used to evaluate the film thickness of the 3-ply biodegradable mask's layered structure. C6-Fluorocarbon based dispersion solution named TUBIGUARD 30-F, and the cross-linking agent TUBICOAT FIX H26 (used for improving the washing durability of the fabric) was procured from CHT Group Germany. The binary solution mixture of TUBIGUARD 30-F and TUBICOAT FIX H26 was spray-coated on the Cotton fabric using a hand-operated spray gun with a distance of 20 cm from the nozzle tip.

The polymer solution was prepared by dissolving 15 wt% of premium quality PLA polymer beads in dichloromethane (DCM) solvent. Dissolution of the PLA polymer was carried out at room temperature in the presence of continuous magnetic stirring at 200 rpm speed. Traditional Indian herbal extracts of Azadirachta Indica (10 wt% with respect to PLA) and Eucalyptus Citriodora (10 wt% with respect to PLA) were added to the polymer solution and mixed thoroughly to achieve a homogeneous solution. Viscosity of polymer solution was analyzed using a Brookfield Viscometer to determine the spinning characteristics of polymer solution. The polymer solution was then subjected to needleless electrospinning using the pilot scale plant machine i.e. Model: Nanospider TM Make: Elmarco s.r.o., Czech Republic, at Ahmedabad Textile Industry's Research Association (ATIRA) (as per assembly in Fig 1) . In the needleless electrospinning assembly, the distance between two electrodes was fixed at 18 cm for obtaining a nano-fibrous layer. Voltage at 8 the collector electrode was adjusted to -30 kV, whereas the rotating electrode voltage was maintained at 60 kV for facilitating the effective formation of nano-fibers. The rotating electrode speed was fixed at 6 rpm for deposition of a nano-fibrous layer on base cotton fabric at the collector terminal. Cotton fabric at the collector electrode was processed at a speed of 0.5m/min, 1m/min, 2m/min, and 3m/min for depositing the nano-fibrous layer. An optimum closely packed nanofibrous layer was achieved at the collector electrode speed of 1 m/min. The optimization of collector processing time was carried out by measuring thickness of nano-fiber layer on base cotton fabric using a digital thickness meter gauge. 

Surface morphology of the PLA nano-fibrous layer on base of cotton fabric was analyzed using the Field Emission Scanning Electron Microscopy (FE-SEM, Carl-Zeiss AG, JSM-6700F, Germany). Morphology of the nano-fibrous layer was recorded for evaluating the compactness in surface area of the electrospun PLA nano-fibers on the cotton surface. Furthermore, morphology of the biodegraded samples was recorded to analyze the change in morphology of face mask after subjecting to the thorough biodegradation process.

Further morphological analysis of the nanofibers was evaluated using atomic force microscopy (Model : Asylum Research MFP3D, Make: Oxford Instruments, UK) at room temperature (25±3 o C), with a scanning area of 05 µm, and total area of 127 µm². AFM analysis helps in understanding the surface roughness patterns, symmetrical variations of the surface, sand porosity of the surface in a quantified form.

The air breathability assessment of face mask was carried out using IS 16289:2014 Annex C standard to measure the differential pressure [52] . IS 16289:2014 measures air resistance using a flow meter (as per Fig 2) . The standard technique can be used to measure an airflow of 8 L/min. The mask's testing sample should provide five different circular test areas of 2.5cm orifice diameter (cumulative area of 4.9 cm 2 ). This standard assessment determines the breathability of mask material by evaluating the pressure difference in air flow through filter media of mask material.

As reported in the standard operating procedure, the air is passed through an inlet valve, and a flowmeter is connected at the inlet of assembly displays the flow rate of air into the assembly, and further, the air is passed through the testing sample for evaluating the change in pressure using two manometers. The pressure difference in air among the inlet and outlet of filter media determines the breathability of mask [52] . The differential pressure drop across filter media is mathematically expressed as per equation 1. 

Bacterial filtration efficiency (BFE) of the face mask was evaluated using the IS 16288 standard technique [53] . The standard procedure determines the efficiency by passage of bacteria containing aerosol through the filtering layer of face mask. According to the standard technique, analysis was carried out using Staphylococcus Aureus ATCC 6538 test bacteria with an inoculum size of 5×10 5 CFU/mL in presence of tryptic soya agar media. The peptone water was used as a dilution media, and testing is carried out at incubation conditions of 37±2°C for 24 hours. The BFE testing on a face mask was facilitated by the face-sided test sample having an area of 10×10 cm, and the sample was conditioned at a temperature of 21±5°C. The flow rate of bacteria-containing 11 aerosols was adjusted to 28.5 L/min, exhibiting mean particle size of the challenging aerosols fixed to 3.0±0.3 micron. The bacterial aerosols were delivered to the test sample using a peristaltic pump in presence of controlled air pressure. The flow rate of the aerosol particles passing through the cascade impactor was adjusted to 28.3 L/min, where the duration of bacterial aerosol delivery time was fixed to 2 min. The agar plates were placed into the cascade impactor, and testing samples are clamped on top of it. After the passage of bacterial aerosol for 2 min, the samples were evaluated for BFE [53] . The mathematical expression for calculating BFE is as per equation 2.

(2) % = ( -) × C: Average plate count total for test control T: Plate count total for testing sample

Splash resistance of the 3 ply face mask using the synthetic blood was evaluated using IS 16289:2014 Annex D standards [52] . According to the standard procedure, mask samples were conditioned at temperature conditions of 27±2°C and 65±2 % relative humidity for replicating the moisture equilibrium at standard environmental conditions. The testing sample was mounted on sample holding fixture such that the inside surface of face mask should be completely visible. The mask sample testing was carried out by dispensing a controlled volume of synthetic blood (approximately 2 ml) through a small diameter cannula (internal diameter of 0.084 cm, and 1.27 cm long) over the conditioned mask sample, under the pressure of 120 mm of Hg. The mask's testing sample was placed at a distance of 30.5 cm for achieving adequate replication of blood splash. Inner side of face mask was observed through the viewing hole (within 10 sec) in presence of suitable lighting to evaluate the penetration of synthetic blood [52] .

The surface wetting characteristics of 3-ply mask were evaluated using a contact angle goniometer (model no. DSA 25E, Kruss GmbH, Germany). Measurement of the wetting contact angle (WCA) was facilitated using a standardized 8 µL droplet of deionized water (DI) at room temperature. WCA was recorded on the cotton-PLA-cotton interface and PLA-cotton interface, by placing a drop of DI water on the surface interface. The standard contact angle was measured using a Young-Laplace fitting method in the software. Each sample was repeated for minimum 4 times and then the final average of values was taken as a standard contact angle. These investigations were crucial to understand the hydrophilic and hydrophobic characteristics of the mask, which helps in understanding the washability for reuse and the specific performance of the components in 3-ply mask.

Computational analysis of the herbal phytochemicals against the potential target bacterial proteins was performed using the docking score functioned LibDock Algorithm [54, 55] . LibDock is a high-throughput algorithm for docking ligands into an active receptor site, aligning ligand conformations to polar and apolar receptor interaction hotspots, and reports the best scoring poses.

The ligand conformations with receptor sites profoundly depend on the structural properties, rotation of bonds, and binding energy [56] . The interaction's docking characteristics were optimized using the Broyden Fletcher Goldfarb Shanno algorithm and consistent force field minimization. Heat map analysis is superior to the dot map or picto-trendline to analyze the spread of infectious disease [57] .

The retrieval of proteins and ligands at the 5 drug target site is sourced from the PDB structural database. The theoretical models of the protein and ligand structures were validated and 13 utilized to analyze the docking score. Major phytochemical constituents of the medicinal Azadirachta indica and Eucalyptus citriodora herbal oils were obtained from the PubChem compound database. The raw protein structures sourced from the protein data bank (PDB) database were further prepared for docking studies by removing all the hetatms and explicit HOH atoms.

The docking studies were performed to understand the effective binding performance of the phytochemicals by removing destructive steric clashes, and alternative conformations, insert missing atoms in incomplete residues, and modeling missing loop regions, and standardizing the atom names. The interactions between receptor and ligand were investigated by analyzing molecular docking, using structural molecular biology and CADD. The purpose of this stochastic protein-ligand interaction analysis is hypothesized to probe an enhanced performance of phytochemicals and their mechanism for inhibiting protein structures of the targeted site by utilizing ligands structures.

Biodegradation studies of the 3-ply mask were evaluated using a cow dung based slurry [58] .

The biodegradation slurry was prepared by adding 50 g of fresh cow dung (derived from local farm) into one-liter water, and the mixture was stirred to achieve proper mixing of components in the biodegradation slurry. The initial weight of mask samples was recorded, and samples were immersed in the biodegradation slurry for 30 days. After 30 days, test samples were removed from the slurry and subjected to washing using water. Washed samples were dried in oven at 70°C for 2 hours, to remove the moisture content from biodegraded samples. Final weight of test samples was measured to evaluate the reduction in weight of the face mask after biodegradation. Jaggery was used to enhance the growth of microorganisms in the biodegradation process; hence 50 g jaggery was added to the biodegradation slurry. Fresh samples of the face mask were weighed and 14 added into the biodegradation slurry for 20 days. The samples were removed from biodegradation slurry and washed thoroughly. The washed samples were dried in the oven at 70°C for a duration of 2 hours, followed by an evaluation of the final weight. Effectiveness of the biodegradation process was assessed depending upon the change in weight (%) of the face mask samples using following equation 3.

(3)

Bacterial filtration efficiency and air permeability of the face mask are highly dependent upon the nano-fibrous electrospun PLA filter media due to its compact structure and enhanced surface area for adsorption on the nano-fibrous layer [59] . Multiple studies have been focused on development of PLA nano-fibrous mats using the conventional electrospinning system (single nozzle electrospinning technique) [60, 61] ; however, the low productivity rate of this process is restricting the industrialization of conventional process [62, 63] . Hence, the current study has been focused on the needleless electrospinning technique of the nano-fibers on base cotton surface, considering the industrial viability of the designed product in pandemic times. Needleless electrospun nano-fibrous layers are substantially crucial for the formation of highly porous, small pore sized, and internally connected porous structured PLA electrospun mats [38] . Industrially scalable needleless electrospinning technique is highly beneficial for developing uniform electrospun mats, with an average fiber diameter of 8±0.2 µm (calculated using ImageJ software).

Fiber diameter is sensitive towards the viscosity of electrospinning solution, distance between the electrodes, and strength of electrostatic field; whereas the thickness of electrospun mats is affected by the duration of fiber deposition and speed of rotation of the collecting electrode [64] . At the optimum collector electrode speed of 1 m/min, mean thickness of the needleless electrospun nanofibrous layer is recorded to be 0.41 mm (calculated using digital thickness meter gauge). As per our previous investigation [40] , the viscosity of herbal extracts containing PLA polymer solution at a rate of 10 rpm was found to be 950 cP at ambient temperature conditions (27°C). The fine fiber diameter of PLA electrospun mats results in ameliorated surface area for aerosol particles'

adsorption on the surface [65] . PLA nano-fibrous layer removes the large particle size of aerosols and particulate matter from the substrate's surface, whereas the fine particles are captured deeper inside the close-packed electrospun filter media [66] . The needleless electrospinning technique has emerged as a novel technique for developing industrially scalable nano-fibrous mats for applications in advanced air filter media [67] [68] [69] . Nano-fibers have characteristic properties of improved surface adhesion, low basis weight with uniform fiber diameter, high porosity, and specific surface area, leading to its utilization as an excellent air filter media [70, 71] . As per the FE-SEM in Fig 3 (A) , uniformity in fiber diameter and dense nano-fibers structure in the needleless electrospun mats, leads to the steady and stable filtration stage in the purification of particulate matter and bacteria from the air The fine diameter nano-scaled highly porous structured electrospun mats [as per Fig 3 (B) ] plays a crucial role in the filtration of air, by adsorbing the particulate material and volatile organic gases [11, 16] . According to the Frazier analysis, the needleless electrospun PLA nano-fibrous layer has mean pore size of 20.1429 microns, maximum pore size distribution of 5.0400, and mean flow pore pressure of 0.604 psi. The stable air filtration is caused due to adsorption of the impurities according to 5 specific mechanisms -(i) Interception, (ii) Brownian diffusion, (iii) Gravity effect, (iv) Electrostatic effect, and (v) Inertial impaction [72] .

These mechanisms may show variations in the nano-fibrous layer's filtration efficiencies, whereas total filtration efficiency is calculated by the cumulative aggregate of all these mechanisms 16 considering the size and shape of impurities in air [73] . Compact and multi-layered structure of face masks is crucial to demonstrate the enhanced results for filtration of micro aerosol particles.

Increment in layers of face mask has been proven to increase filtration efficiency and differential pressure of the face mask, enhancing the protection from harmful pathogens and viruses [74] . In the present study, 3-ply Cotton-PLA-Cotton mask recorded face mask's breathability due to low square roughness value of 423±50 nm [27] . The symmetrical variations of surface were calculated using the roughness skewness value which is found to be 0.417. The distribution of nanofiber roughness around the mean surface was calculated using kurtosis value, which was found to be 0.328. The surface roughness of the nanofibers directly influences its adhesion with the fabric surface (in this case, cotton fabric), and helps in maintaining the hydrophobic nature [40, [75] [76] [77] .

The Hydrophobicity of the PLA-Neem electrospun layer is attributed to molecular groups like CH3, -C=O, and -CO, which possess polarity, i.e. charged state repels the ions present in water [40] . Further, the electrospinning action gives non-woven nature to the PLA/Neem fibers, which result in a surface exhibiting rough, porous, and heterogeneous morphology . Porous and rough morphology of the surface results in generation of air-pockets entrapped between pore and rough-textured surfaces, which act as air-pockets between pores and heterogeneous rough surfaces. These air-pockets hold entrapped air that repels water molecules and thereby restricts its entry inside the porous surface and the acting capillary forces. Gore et al. have stated that the small size of the pores existing on the surface exhibit a high capillary force of 22 attraction considering the big-sized pores. Thus, the small-sized pores demand immense pressure to open up (in the present study, pressure needed for water to cross through the surface exhibiting superhydrophobic nature) [40, [83] [84] [85] [86] .

The increased demand for an anti-microbial filtration layer has motivated the researchers to incorporate the encapsulated nanoparticles, enhancing the bacterial inhibition of airborne microbes. An investigation by Jeongan Choi demonstrated the encapsulation of bio-based Sophora flavescens herbal extract nanoparticles enhances anti-microbial air filtration, with 99.99% filtration efficiency and 99.98% bacterial efficiency [87] . Nano-dispersed herbal extracts of Azadirachta Indica in the bi-layered electrospun mats were also reported to demonstrate antimicrobial characteristics for filtering the micro-scale particulate matter as well as bacteria [88] .

The antibacterial activity of Azadirachta Indica and silver nanoparticles on electrospun polylactide fibers are demonstrated to exhibit improved bacterial filtration nano-membranes [89] . In addition to that, the presence of herbal extracts of Eucalyptus Citriodora has showcased antiviral characteristics against the infectious herpes simplex virus [90] . 

Biodegradation of face masks is advantageous for combatting the post-pandemic environmental impacts of COVID-19 pandemic on the ecological systems. The release of synthetic microfibers from commercial non-woven masks into the environment may result in harmful effects on humankind. The present study has investigated the biodegradation characteristics of used face masks, immersing it into the biodegradation slurry consisting majorly of fresh cow-dung. The freshly prepared cow-dung slurry is used to investigate the biodegradation characteristics since the presence of bacteria in the cow-dung has been recorded to exhibit degradation of commodity plastics [58] . Cow-dung microflora consists of about 60 various types of bacteria, dominated by Corynebacterium sp., Bacillus sp., Lactobacillus sp., Aspergillus, and trichoderma. In addition to 26 these, the cow-dung slurries contain about 100 species of protozoa and 2 yeasts [95] . The slurries have been reported to contain a various group of bacteria such as Serratia, Acinetobacter, and Alcaligenes spp [96, 97] , as plant growth-promoting bacteria. In the presence of composting conditions, naturally occurring polylactide films have showcased aerobic biodegradation characteristics [98] , primarily undergoing hydrolytic cleavage of ester bonds in an aqueous medium to break the macromolecular chains [99] . In the present study, nano-fibrous PLA layer was completely degraded when immersed in the jaggery based biodegradation slurry. Degradation of PLA has been facilitated in the presence of organic waste to undergo anaerobic digestion [100] ; similarly, the sugarcane bagasse has been recorded to exhibit anaerobic biodegradation of cellulosic fibers [101, 102] . Since the significant constituents of jaggery are sucrose, the additive accelerates the biodegradation rate of PLA and cotton fibers in the biodegradation slurry. The hydrophobic coating layer of C6-fluorocarbon is found to be biodegraded which is evident from the hydrophilic (water contact angle = 0 o ) nature of the top layer after biodegradation. The biodegrading microorganisms have most probably caused the scission of the bond between C6fuorocarbon molecules and the cellulosic groups present in the cotton. Thus, the face mask showcased improved degradation as the change in the weight of mask sample increased from approx. 7% to approximately 12% (as per data of Table 1 and Table 2 ). 

In the present study, we have reported the characteristics and performance of a 3-ply biodegradable face mask containing encapsulated phytochemicals to ameliorate bacterial filtration efficiency. 

COVID-19 and flu, a perfect storm

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A critical perspective on early communications concerning human health aspects of microplastics

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Effectiveness of Cloth Masks for Protection Against Severe Acute Respiratory Syndrome Coronavirus 2, Emerg

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Bio-based and Photocrosslinked electrospun antibacterial nanofibrous membranes for air filtration

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Electrospun Mater. Their Allied Appl

Silk-Based Composite Scaffolds for Tissue Engineering Applications

A computational prediction of SARS-CoV-2 structural protein inhibitors from Azadirachta indica (Neem)

Antiviral activity of sandalwood oil against Herpes simplex viruses-1 and -2

Chinese herbal medicine for coronavirus disease 2019: A systematic review and meta-analysis

Drug treatments for covid-19: Living systematic review and network meta-Analysis

Assessment of endocrine disruption potential of essential oils of culinary herbs and spices involving glucocorticoid, androgen and vitamin D receptors

A brief review of socio-economic and environmental impact of Covid-19

Prospect of biobased antiviral face mask to limit the coronavirus outbreak

Air filtration and antimicrobial capabilities of electrospun 36

PLA/PHB containing ionic liquid

Biodegradability and biodegradation of poly(lactide)

Heterogeneous wettable cotton based superhydrophobic Janus biofabric engineered with PLA/functionalized-organoclay microfibers for efficient oil-water separation

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Progress in silk materials for integrated water treatments: Fabrication, modification and applications

Nanocellulose based biodegradable polymers

Biodegradable Polymeric Solid Framework-based Organic Phase Change Materials for Thermal Energy Storage

Biodegradability of cellulose fabrics

Biodegradability study on cotton and polyester fabrics

Biodegradable detergents from Azadirachta Indica (neem) seed oil, Leonardo Electron

Molecular interactions and antimicrobial activity of curcumin (Curcuma longa) loaded polyacrylonitrile films

Egg albumin PVA hybrid membranes for antibacterial application

THE PROCESS FOR EXTRACTION OF ESSENTIAL OIL AND THE PRODUCT OBTAIN THEREFORE

Bureau of Indian Standards, Medical Textiles -Method for Evaluation of the Bacterial Filtration Efficiency of Surgical Face Masks

Computational study on new natural compound inhibitors of indoleamine

Virtual screening and molecular dynamics study of potential negative allosteric modulators of mGluR1 from Chinese herbs

Validation studies of the site-directed docking program LibDock

Communicating infectious disease prevalence through graphics: Results from an international survey

Enhanced biodegradation of low and high-density polyethylene by novel bacterial consortia formulated from plastic-contaminated cow dung under thermophilic conditions

Nanoporous PLA/(Chitosan Nanoparticle) composite fibrous membranes with excellent air filtration and antibacterial performance

Mechanical properties and in vitro degradation of electrospun bio-nanocomposite mats from PLA and cellulose nanocrystals

Biodegradable electrospun poly ( L -lactide ) fibers containing antibacterial silver nanoparticles

Technological advances in electrospinning of nanofibers

Mass production of nanofibre assemblies by electrostatic spinning

Controlled gentamicin release from multi-layered electrospun nanofibrous structures of various thicknesses

Preparation of hierarchical structured nano-sized/porous poly(lactic acid) composite fibrous membranes for air filtration

Depth filtration of airborne agglomerates using electrospun bio-based polylactide membranes

Honeycomb-like polysulphone/polyurethane nanofiber filter for the removal of organic/inorganic species from air streams

The formation of ultrafine polyamide 6 nanofiber membranes with needleless 40 electrospinning for air filtration

Needleless electrospinning for scaled-up production of ultrafine chitosan hybrid nanofibers used for air filtration

Polyacrylonitrile / Silver Nanoparticle Electrospun Nanocomposite Matrix for Bacterial Filtration

Tailoring mechanically robust poly(mphenylene isophthalamide) nanofiber/nets for ultrathin high-efficiency air filter

Filtration Properties of Electrospinning Nanofibers

Electrospun Nanofibers Membranes for Effective Air Filtration

Filtration Efficiencies of Nanoscale Aerosol by Cloth Mask Materials Used to Slow the Spread of SARS CoV-2

Filtration Efficiencies of Nanoscale Aerosol by Cloth Mask Materials Used to Slow the Spread of SARS CoV-2

mucoadhesive bioplastic patch via coaxial polylactic acid (PLA) based electrospun nanofibers with antimicrobial and wound healing application

Bionic creation of nano-engineered Janus fabric for selective oil/organic solvent absorption

Nanotechnology for Oil-Water Separation

Water Technol

Functionalized nanofibrous coating on cotton fabrics

Environmentally friendly fabric finishes

Sustain. Appar. Prod. Process. Recycl

Design of Experiment Approach to Optimize Hydrophobic Fabric Treatments

Review on Three-Dimensionally Emulated Fiber-42

Embedded Lactic Acid Polymer Composites: Opportunities in Engineering Sector

Directional Fluid Gating by Janus Membranes with Heterogeneous Wetting Properties for Selective Oil-Water Separation

Wettability of porous surfaces

Development of highly porous, Electrostatic force assisted nanofiber fabrication for biological applications

Starch/PVA hydrogels for oil/water separation

Herbal Extract Incorporated Nanofiber Fabricated by an Electrospinning Technique and its Application to Antimicrobial Air Filtration

Antibacterial bi-layered polyvinyl alcohol (PVA)-chitosan blend nanofibrous mat loaded with Azadirachta indica (neem) extract

Development of bacterial-resistant 43

electrospun polylactide membrane for air filtration application : Effects of reduction methods and their loadings

Antimicrobial electrospun ultrafine fibers from zein containing eucalyptus essential oil/cyclodextrin inclusion complex

Computational evaluation of major components from plant essential oils as potent inhibitors of SARS-CoV-2 spike protein

Screening a peptidyl database for potential ligands to proteins with side-chain flexibility

Secondary metabolites with antinematodal activity from higher plants

Decoding multifarious role of cow dung bacteria in 44 mobilization of zinc fractions along with growth promotion of C . annuum L

Aerobic heterotrophic bacteria and petroleum-utilizing bacteria from cow dung and poultry manure

Microbial degradation of petroleum hydrocarbons in a polluted tropical stream

Biodegradation of modi fi ed Poly ( lactic acid ) based biocomposite fi lms under thermophilic composting conditions

Characterization of the Degradation of Polylactic Acid Polymer in a Solid Substrate Environment

Improvement of methanogenic activity of anaerobic digestion using poly(lactic L-acid) with enhanced chemical hydrolyzability based on physicochemical parameters

Biological pretreatment of sugarcane bagasse with basidiomycetes producing varied patterns of biodegradation

The use of thermochemical pretreatments to improve the anaerobic biodegradability and biochemical methane potential of the sugarcane bagasse

The authors are thankful to Dr. C. P. Ramanarayanan, Vice-Chancellor of DIAT (DU), Pune, and