key: cord-1052757-hgvggku4 authors: Kumar, Aditya; Nath, Kalpita; Parekh, Yash; Enayathullah, M. Ghalib; Bokara, Kiran Kumar; Sinhamahapatra, Apruba title: Antimicrobial silver nanoparticle-photodeposited fabrics for SARS-Cov-2 destruction date: 2021-10-29 journal: Colloid Interface Sci Commun DOI: 10.1016/j.colcom.2021.100542 sha: 67d8c520d20f8d9c9d3c7127ddf4b2af6521174b doc_id: 1052757 cord_uid: hgvggku4 Surfaces containing antiviral nanoparticles could play a crucial role in minimizing the virus spread further, specifically for COVID-19. Here in, we have developed a facile and durable antiviral and antimicrobial fabric containing photodeposited silver nanoparticles. Scanning and transmission electron microscopy, UV-VIS spectroscopy, and XPS are used to characterize the silver nanoparticles deposited cloth. It is evident that Ag(0)/Ag(+) redox couple is formed during fabrication, which acts as an active agent. Antiviral testing results show that silver nanoparticles deposited fabric exhibits 97% viral reduction specific to SARS-CoV-2. Besides its excellent antiviral property, the modified fabric also offers antimicrobial efficiency when tested with the airborne human pathogenic bacteria Escherichia coli and fungi Aspergillus Niger. The direct photodeposition provides Ag-O-C interaction leads to firmly grafted nanoparticles on fabric allow the modified fabric to sustain the laundry durability test. The straightforward strategy to prepare an efficient antimicrobial cloth can attract rapid large-scale industrial production. On 11 th March 2020, World Health Organization (WHO) declared infection as a pandemic [1] . Since then, the SARS-CoV-2 virus has been spreading rapidly worldwide for a short time. Due to its high contagious nature, millions of people are infected by this virus, resulting in millions of deaths and continuing. Furthermore, it is a new virus and has been undergoing mutations and evolving as new strains to which humans have no previously developed immunitya common factor of a pandemic. New variants of SARS-Cov-2 have been confirmed in several countries/territories/areas. In modern history, a cruel example of a pandemic is an outbreak of the Spanish Flu in 1918-19, due to which 500 million people were infected and 100 million people have died [2] . Pandemics continue to remain a severe threat to humans at present. Although some nations have recently started vaccines for COVID-19, such as BNT162b2 and mRNA-1273, WHO has not yet approved these vaccines for worldwide vaccination, also, the time required to achieve immunity in the vaccinated person is still hard to estimate. The longevity of immunity after vaccination is also not established. Furthermore, the vaccination of every individual in the world will require many years. The SARS-Cov-2 virus has a high propensity for genomic recombination and mutation, generating new strains, and the vaccine may not be equally efficient for each strain. creating an antiviral and anti-pathogen coating on everyday inanimate objects. A few reports are recently published. Murti et al. demonstrated rapid inactivation of SARS-CoV-2 using a biofunctional coating of benzalkonium chloride [5] . A hydrophobic surface is developed by Kumar et al. using copper nanoparticles for photo-assisted anti-viral properties [6] . Carbonbased materials are also proposed as promising antiviral agents [7] . The growth of Nanotechnology opens up new weapons for researchers. Nanoparticles are often reported for their antimicrobial activity and their low toxicity towards animal beings [7] [8] [9] [10] [11] [12] [13] . For example, silver nanoparticles (AgNP) are exhibited antimicrobial activity against several types of bacteria and fungi. Antiviral activities of silver nanoparticles against viruses such as HIV-1 [14, 15] , hepatitis B [16] , herpes simplex [17] , respiratory syncytial [18] , monkeypox [19] , Tacaribe [20] , and H1N1 influenza A virus [21, 22] are reported. In general, the antiviral/antimicrobial mechanism of silver nanoparticles is found to be likely the physical inhibition of binding between the virus and host cell/surface. This property of silver nanoparticles makes it the most promising candidate for the destruction of the SARS-Cov-2 [23, 24] . It is also essential that besides the efficiency and durability, the developed surface should also easily achievable via the economic process. In this concern, photo-assisted deposition of silver nanoparticles on cloth surface facilitated by photooxidation of fabric cellulose could be one most promising approach [25] . The size of the silver nanoparticles is also one of the major deciding parameters for the efficiency and durability of the developed it consists of Ag 0 and Ag + . Most importantly, the silver nanoparticles AgNPs-cloth surface inhibited the SARS-Cov-2 propagation invitro by killing the virus. Silver nitrate (Extra Pure) was purchased from HiMedia Laboratories Pvt. Ltd, India. Other chemicals were purchased from Avator Performance Materials India Limited (Rankem). All the chemicals were used without further purification. Cotton fabric cloth was procured from the local market (Dhanbad, India). The cotton cloth was cut into the dimensions of 2×2 cm 2 pieces, then washed several times ultrasonically in the mixture of acetone and distilled water, and finally dried. In a typical procedure (Fig. 1) , the cleaned cotton cloth was immersed in an aqueous solution of 1 mM AgNO 3 and kept under the UV lamp (wavelength 254 nm, irradiance 6.82 mW/cm 2 ) for 30 min. Later, the cloth was removed from the solution and dried at 50 °C. The color of the cotton cloth was changed from white to dark brown. Silver nanoparticles AgNPs-cloth was prepared successfully and after that used for further experiments. The surface morphology of the samples was carried out using a scanning electron microscope (SEM, JEOL, JSM-6480LV). The elemental analysis of the samples was performed using X-ray Photo-Electron Spectroscopy (XPS) with Auger Electron Spectroscopy (AES) module and C60 sputter gun (PHI 5000 Versa Probe III, FEI Inc.). The UV-VIS-NIR Spectrophotometer (Agilent, Cary 500) was used to record absorption spectra. The High-Resolution Transmission Electron Microscope (HRTEM) (Thermo Scientific, Talos F200X G2) was used to obtain surface morphology. The laundry test of the modified cloth was performed to study the washing durability [28] . In a typical process, a piece of cloth was dipped into an aqueous solution of laundry detergent and stirred for 1 h. The fabric was collected and washed with deionized water and dried at 50°C in a hot-air oven. The experiment was repeated 5 times, and the washed fabric was characterized. The bacterial interaction with the cloth samples was tested using the E. coli bacteria. Initially, the Mueller Hinton agar (Himedia) media was used as a culture medium for the test. The media was autoclaved and poured into the sterilized Petri plates for solidification. The E. coli bacteria (100 µl, fresh) were spread over the Petri plates. The samples were cut into an equal size square shape and placed on the agar petri plates. The plates were incubated at 37 °C for different time intervals like 1, 2, and 3 days. After incubation for regular intervals, images were taken and observed in the inhibition zone for all tested samples. Vero cells were maintained in Dulbecco Minimum Essential Medium (DMEM) (Gibco) containing 10% Fetal Bovine Serum (FBS) (Gibco) at 37°C, 5% CO 2 . Cells were seeded into 96-well tissue culture plates 24 h prior to infection with SARS-CoV2 (Indian/a3i clade/2020 isolate) in a BSL3 laboratory. The effect of silver nanoparticles on cloth surface was tested against the SARS-CoV2 was used as a positive control. The log viral particles and a semi-log graph were plotted using Graph Pad Prism 5 software (ver 5.03) through the linear regression equation obtained using the RNA extracted from the known viral particles by RT-qPCR, using N-and ORF1ab genes specific to SARS CoV-2 virus and percent viral reduction was calculated [30] . The C t values of the N gene, E gene, and ORF 1ab were considered to estimate the % viral reduction and log viral particles. In this work, an antiviral (COVID-19) and antimicrobial coating on cloth surfaces have been developed by photo-depositing silver nanoparticles on its surface using UV irradiation (Fig. 1) . This method is facile and does not require any additional reducing agent. When cloth containing cellulose is irradiated by UV, the alcohol (-OH) groups present on cloth work as a sacrificial oxidant and photo-oxidize into aldehyde (-CHO) groups, and those are converted into carboxylic acid (-COOH) groups, as shown in the Scheme 1 [25, 31] . The surface morphologies of bare and AgNPs-cloth were examined by the SEM (Fig. 2) . The deposition of the silver nanoparticles creates the roughness at the nanoscale via trapping of nanoparticles between the cellulose fibers, whereas these features are not observed on the bare sample. The silver nanoparticles were separated by sonication of AgNPs-cloth in an ethanol solution and used for HRTEM analysis. Fig. 3 (a) displays the HRTEM images of spherical nanoparticles. The size distribution is plotted in Fig. 3 (b) , indicating a wide range of particle size distribution with an average value of about 10 nm. The HRTEM image presented in the inset of Fig. 3 (b) shows the lattice d-spacing of about 0.23 nm corresponding to Ag (111), suggesting the formation of crystalline silver nanoparticles [32] . EDS analysis was also J o u r n a l P r e -p r o o f carried out to examine the elemental information, and it confirms the presence of Ag (Fig. 3 (c)). EDS analysis of silver nanoparticles obtained from the AgNPs-cloth. The cloth samples were also analyzed by XPS (Fig. 4) . The XPS survey (Fig. 4 (a) The high-resolution O1s XPS spectra of cloth samples are presented in Fig. 4 (c) . Bare cloth shows a single peak at 531.4 eV, whereas the AgNPs-cloth shows two more peaks at 530.7 and 533.9. The peak at 531.4 eV corresponds to the cellulosic O. The peaks at 530.7 and 533.9 correspond to the carboxylic acids formed during coating and hydroxyl group, respectively [34] . The core-level high-resolution Ag 3d XPS spectrum, shown in Fig. 4 (d) , confirms silver nanoparticles' presence on the AgNPs-cloth. The deconvolution (Gaussian peak fitting) of the obtained spectrum unveils the existence of Ag + and Ag 0 oxidation states with a peak separation of 0.9 eV. The peak at 367.3 eV corresponds to 3d 5/2 of Ag + , and the peak at 368.2 eV represents the 3d 5/2 of Ag 0 [28, 35] . The loss features corresponding to metallic silver are also observed to the higher binding energy of each spin-orbit component. From the corresponding peak ratio, the ratio of Ag 0 /Ag + is approximate 2.3. The atomic % of Ag in the AgNPs-cloth is 0.5%, as indicated by XPS elemental composition analysis. Therefore, the significant peak alteration in C1s and O1s XPS spectra after coating confirms the mentioned mechanistic path in the Scheme 1. Due to photo-oxidation of cellulosic alcohol groups to an aldehyde, which further converts into the carboxylic acid group, is a cause of photo-reduction of Ag + to Ag 0 and formation of silver nanoparticles on cloth as confirm by the Ag3d XPS spectra. The absorption spectra of AgNPs-cloth and bare cloth were also recorded in diffuse reflectance spectroscopy (DRS), and results are presented in Fig. 5 . The absorption spectrum of the AgNPs-cloth exhibits strong absorption of UV-VIS light, while the bare cloth has no significant light absorption. The light absorption in the UV and visible region suggests the presence of silver (Ag + ) oxide and silver (Ag 0 ) on the AgNPs-cloth, respectively [23] [36] . The broad absorption peak maxima at ~430 nm is observed for the surface plasmon resonance of silver nanoparticles [36] . The excellent stability of the silver nanoparticles on cloth can be attributed to Ag-O interaction. J o u r n a l P r e -p r o o f The laundry durability of the AgNPs-cloth was further examined by using regular liquid detergent. The XPS analysis ( Fig. 6 (a) and (b) ) of the washed AgNPs-cloth does not indicate any significant alteration compared to the pristine AgNPs-cloth ( Fig. 4 (a) and (d) ). The atomic % of Ag is 0.48% after wash. The absorption spectrum of the washed cloth was also recorded (Fig. 6 (c) ). There is no significant change observed in absorption spectra after wash, which implies that coating has excellent laundry durability. The achieved durability of AgNPs-cloth is attributed to the strong interaction of silver nanoparticles and cloth surface. As the silver nanoparticles formed on cloth surface itself during photodeposition, as shown in The antibacterial susceptibility test was conducted on AgNPs-cloth using the disk diffusion method against the E. coli bacteria. For comparison, the bacterial test was also performed using the bare cloth. The results are presented in Fig. 7 (a) . It shows an inhibition zone or no bacterial growth surrounding the AgNPs-cloth, whereas prominent bacterial growth is visible for the bare cloth. The inhibition zone was measured as a radius of no bacterial growth area, and the inhibition zone at different incubation times are tabulated in growth [37] [38] [39] . Besides, proteins present on the outer membrane of bacteria are made of O, N, P, S and exhibit electron donor tendency. Ag 0 /Ag + redox couples interact with these proteins, resulting in the damage of the bacterial membrane. Additionally, thiol groups present in protein and enzymes interact with Ag + /Ag 0 [40, 41] . Further, it is also reported that Ag + ion leads to transforming DNA from a naturally relaxed state to a condensed form, which leads to DNA losing its replication ability [38] . The inhibition zone is decreased to 10 mm after 2 days incubation and further reduced to 7 mm after 3 days incubation. The decrease of the inhibition zone is due to the decline in the number of active sites present on the AgNPscloth; i. e. over time, Ag 0 /Ag + are already engaged in antibacterial activities, and a low number of active sites are only available for further antibacterial activities. For anti-fungal contamination, a fungal susceptibility test was carried out using the disk diffusion method. Both bare and AgNPs-cloth were tested against the A. niger fungus. J o u r n a l P r e -p r o o f Journal Pre-proof germination [42] , resulting in reduced fungal growth. Here also, the decrement of the inhibition zone was observed after 6 and 7 days incubation for the same reason. The antiviral tests were performed using SARS-CoV-2 (Indian/a3i clade/2020 isolate) in a BSL3 lab. The test results reveal that the AgNPs-cloth sample confers the 95 and 97% viral reduction at 30 and 60 min contact time with the virus, respectively, concerning the detection of nucleocapsid gene (N-gene) through qRT PCR (Fig. 8) . Furthermore, the application of the Envelope gene (E gene) and Open Reading Frame (ORF) specific to the SARS-Cov-2 virus showed more than 99% viral reduction at 30 and 60 minutes exposure with ~2 log viral reduction as compared with the untreated cloth (Fig. 8) . contrast, the S2 subunit is formed of a trimeric stalk and comprises a fusion peptide (FP) and two heptad repeats (HR1 and HR2), which operate the fusion of viral and host membranes [43, 44] . The primary function of the S1 glycoprotein spikes is to bind the virus with receptor sites on the host cells/surface. Although several other proteins are present on the viral envelope, glycoprotein spikes heads (S1 subunits) are more exposed to the exterior and possibly interact with Ag nanoparticles of AgNPs-cloth. It is reported that the S1 subunit has C-terminal (CTD) subdomains located in the vicinity of the receptor-binding domain [43, 44] . Ag + ions are electrostatically attracted with negatively charged CTD, and Ag 0 may attract towards positively charged NTD, leading to viral spikes adhesion to the silver nanoparticles. Additionally, the virus membrane can also be damaged through Ag 0 /Ag + interaction with the protein of the virus's outer membrane made of functionalities that contain O, N, P, S and S2 S1 Viral envelope AgNPs-cloth Protective Face Mask Filter Capable of Inactivating SARS-CoV-2, and Methicillin-Resistant Staphylococcus aureus and Staphylococcus epidermidis Photoactive Antiviral Face Mask with Self-Sterilization and Reusability Carbon-Based Nanomaterials: Promising Antiviral Agents to Combat COVID-19 in the Microbial-Resistant Era Antiviral activity of silver nanoparticle/chitosan composites against H1N1 influenza A virus In situ deposition of silver nanoparticles on the cotton fabrics Investigation of antibacterial activity of cotton fabric incorporating nano silver colloid Fabrication of Antimicrobial Perspiration Pads and Cotton Cloth Using Amaranthus dubius Mediated Silver Nanoparticles Interaction of silver nanoparticles with HIV-1 Rapid assessment of antiviral activity and cytotoxicity of silver nanoparticles using a novel application of the tetrazolium-based colorimetric assay Silver nanoparticles inhibit hepatitis B virus replication Inhibition of Herpes Simplex Virus Type 1 Infection by Silver Nanoparticles Capped with Mercaptoethane Sulfonate Silver nanoparticles inhibit replication of respiratory syncytial virus A preliminary assessment of silver nanoparticle inhibition of monkeypox virus plaque formation Interaction of silver nanoparticles with Tacaribe virus Inhibitory effects of silver nanoparticles on H1N1 Virucidal effect against coronavirus SARS-CoV-2 of a silver nanocluster/silica composite sputtered coating Photo-induced growth of silver nanoparticles using UV sensitivity of cellulose fibers Dose and Size-Dependent Antiviral Effects of Silver Nanoparticles on Feline Calicivirus, a Human Norovirus Surrogate, Foodborne pathogens and disease Synthesis and antibacterial activity of silver nanoparticles against gram-positive and gram-negative bacteria Ag nanoparticles-coated cotton fabric for durable antibacterial activity: derived from phytic acid-Ag complex Clinical management of severe acute respiratory infection when novel coronavirus (nCoV) infection is suspected, Interim guidance The FDA-approved drug ivermectin inhibits the replication of SARS-CoV-2 in vitro Review: Catalytic oxidation of cellulose with nitroxyl radicals under aqueous conditions Encapsulated Silver Nanoparticles Can Be Directly Converted to Silver Nanoshell in the Gas Phase XPS Studies of Chemically Modified Banana Fibers X-ray Photoelectron Spectroscopic and Transmission Electron Microscopic Characterizations of Bacteriophage-Nanoparticle Complexes for Pathogen Detection In situ growth of Ag/Ag 2 O nanoparticles on gC 3 N 4 by a natural carbon nanodot-assisted green method for synergistic photocatalytic activity Enhanced solar photodegradation of toxic pollutants by long-lived electrons in Ag-Ag2O nanocomposites Green synthesis of silver nanoparticles: biomolecule-nanoparticle organizations targeting antimicrobial activity, RSC Advances A mechanistic study of the antibacterial effect of silver ions on Escherichia coli and Staphylococcus aureus The Effect of Charge at the Surface of Silver Nanoparticles on Antimicrobial Activity against Gram-Positive and Gram-Negative Bacteria: A Preliminary Study Interaction of silver nitrate with readily identifiable groups: relationship to the antibacterial action of silver ions Antifungal activity of silver and copper nanoparticles on two plant pathogens, Alternaria alternata and Botrytis cinerea Structure, function, and antigenicity of the SARS-CoV-2 spike glycoprotein Cell Entry Depends on ACE2 and TMPRSS2 and Is Blocked by a Clinically Proven Protease Inhibitor Mode of antiviral action of silver nanoparticles against HIV-1 Potent antiviral effect of silver nanoparticles on SARS-CoV-2, Biochemical and Biophysical Research Communications Nanoparticles as antimicrobial and antiviral agents: A literature-based perspective study