Research Article | Open Access
Mika Umpo1 , Tumbi Lollen2, Moji Jini3 and Jyothinath Kothapalli4
1Department of Microbiology, Tomo Riba Institute of Health and Medical Sciences, Naharlagun – 791 110, Arunachal Pradesh, India.
2Department of Dentistry, Tomo Riba Institute of Health and Medical Sciences, Naharlagun- 791 110, Arunachal Pradesh, India.
3Department of Surgery, Tomo Riba Institute of Health and Medical Sciences, Naharlagun-791110, Arunachal Pradesh, India.
4Department of Anatomy, Tomo Riba Institute of Health and Medical Sciences, Naharlagun- 791 110, Arunachal Pradesh, India.
J Pure Appl Microbiol. 2021;15(4):2177-2182 | Article Number: 7207
https://doi.org/10.22207/JPAM.15.4.41 | © The Author(s). 2021
Received: 30/07/2021 | Accepted: 04/10/2021 | Published: 02/11/2021
Abstract

SmartCoat is a novel technology with titanium dioxide (TiO2) nanoparticles, isopropyl alcohol, and distilled water as the active ingredients. TiO2, along with water and oxygen, generates highly reactive OH radicals that can neutralize bacteria and other microorganisms and remove volatile organic compounds (VOCs). Smart coat requires air circulation and a light source for its catalytic activity. The efficacy of TiO2 in industrial setups and dental devices has been documented. The present study aimed to evaluate the efficacy of TiO2 in preventing microbial growth in an operating theater (OT) where maximum sterility is desired to prevent sepsis and nosocomial infections. Among the four operating theaters, two were selected. Periodic swab samples taken over a period of nine months from OT 3 (Smart coated) and OT 4 (Control) showed minimal variations in terms of microbial growth in the processed swabs. The findings were statistically analyzed using a paired-sample t-test. The computed value of ‘t’ i.e., 2.084 was lower than the critical value of 3.18 at 3 deg of freedom (df) and hence was not significant. The null hypothesis cannot be rejected (p=0.129>0.05) at the 5% level of significance. SmartCoat with TiO2 was not effective in preventing microbial growth on biomedical devices in the OT. The product may not be suitable for operating theaters unless it is supplemented by other sterilization procedures. However, it can be used in other healthcare settings and in public places.

Keywords

SmartCoat, titanium dioxide, nanoparticles, relative light units, operation theatre, nosocomial infections, sepsis

Introduction

Titanium dioxide (TiO2) is a considerably effective nano-semiconductor photocatalyst that is commonly utilized in organic and inorganic compound oxidation in water and air because of its extended photostability and vigorous oxidative potential. TiO2 is a cheap and innocuous material1 that produces extremely reactive OH radicals in the presence of O2 and H2O. These OH radicals can effectively prevent bacterial growth and development.2

Infections associated to bacteria pose a considerable threat to the well-being of patients in the healthcare system. Infections with Staphylococcus aureus is the leading cause of patient morbidity. Several reports have indicated the existence of methicillin-resistant Staphylococcus aureus on hospital surfaces for up to 5 months. During non-lethal UV light exposure, TiO2 nanoparticles degrade organic compounds by continuous discharge and the emergence of superoxide ions and hydroxyl radicals, which restrict the growth of methicillin-resistant Staphylococcus aureus.3

SmartCoat is a new-generation technology with the following active ingredients: TiO2, nanoparticles, isopropyl alcohol, and distilled water. SmartCoat India Pvt. Ltd claims that it has antibacterial, antiviral, and antifungal properties and removes volatile organic compounds (VOCs). It is a deodorizing agent, and it acts as a self-cleaning agent. TiO2 has a nano size of 2–3 nm for the greatest coverage to reacts with any light source to eradicate 99.9% of fungi, bacteria, viruses, and VOCs. According to the SmartCoat India Pvt. Ltd, 1000 relative light units (RLU) are recommended microbial levels as per the Lumitester document. The supply of light (measured in RLU) and air circulation is necessary for the functioning of this coating, as it is developed on photocatalyst technology.

There is a lack of literature on the efficacy of SmartCoat in microbial prevention in the primitive zones of health care. Various approaches with different compositions of surface coats have yet to be explained. The present study aimed to evaluate the advantage of TiO2 coated surfaces in preventing substantial microbial growth in the OT of TRIHMS Hospital, where the maximum sterility procedure is adopted.

Materials and Methods

This cross-sectional observational study was carried out in the Department of Microbiology, Tomo Riba Institute of Health & Medical Sciences (TRIHMS), a 300 bed state hospital located in the capital complex of Naharlagun, Arunachal Pradesh, from June to December 2020. Among the four operating theaters (OTs) at TRIHMS, two OTs were selected for the study. To avoid any bias, two OTs (OT 3 and OT 4) were selected randomly. The study proposal was approved by the institutional research committee and the institutional ethics committee.

Sampling and cultivation
One swab was taken from the OT table, bedside monitor, anesthesia machine, and operating microscope before application of TiO2 (SmartCoat). Darcon-tipped sterile swabs hydrated with sterile water were swabbed on the surface to be tested. The test swab was then inserted in the tube, shaken to integrate in the water at the bottom of the swab tube. The swab tube was then tested using the Kikkoman Lumitester PD 20, and the results were recorded.

Thereafter, Germisep tablets were mixed in water (1 tablet in 10 L water). Germisep dissolves chlorine in water. This solution was then sprayed on the interiors of OT 3 with an electrostatic sprayer (ESS). The ESS sprays electrically charged molecules to the liquid to increase its spread and adherence over the surface .

SmartCoat and its application
The photo catalyst SmartCoat product is a liquid containing TiO2 nanoparticles as the main ingredient, along with isopropyl alcohol and distilled water. Regardless of the surface to which it is applied, SmartCoat technology neutralizes any organic matter upon contact via its oxidative ability, which is triggered utilizing any available light.

SmartCoat was applied to the walls, floor, roof, tables, surgical items, and all equipment inside OT 3 by an ESS and supplied sufficient light and air. This was left to dry for 30 min with all lights switched on, in OT 3. After 30 min, swabs were taken from the same three sites.

The collected swabs were taken to the Department of Microbiology laboratory and were inoculated on Sabouraud dextrose agar (SDA) and nutrient agar. Readings of culture media were performed and recorded after 24 h of incubation at 37°C. Growth was recorded, and biochemical tests were performed to identify the isolates.

Thereafter, periodic swabs were collected and cultured to identify the microbial flora. Periodical swabs were collected at the end of 1st week, 3rd week, 1st month, 2nd month, 3rd month, 6th month and 9th month after applying SmartCoat.

Statistical Analysis
Statistical analysis was performed using SPSS version 16.0. Frequencies and percentages (%) were calculated. Significant differences in antimicrobial effects were assessed using Student’s t-test. Statistical significance was set at p <0.05.

RESULTS

Periodic culture isolates from both OT 3 (with SmartCoat) and OT 4 (without SmartCoat) showed minimal variation. Staphylococcus (42.2%), Moraxella (14.2%), and Bacillus species (14.2%) were mostly isolated from the surface of OT 4. However, Bacillus species (22.2%), Micrococcus (22.2%), and Alcaligenes (22.2%) were most commonly observed on the OT 3 surface coated with SmartCoat. At nine months OT 3 (with SmartCoat) showed low RLU, and only Moraxella species were grown in one of the cultures. However, in OT 4, Staphylococcus, Moraxella, and fungi were observed.

Fig. 1. Culture and stained image representing the growth of Aspergillus Niger.
A. Initial white colonies, B. While colonies changed to black after few days producing conidial spores. The edges of colonies appear pale yellow producing radial fissures. C. Staining image representing Aspergillus Niger.

The computed value of ‘t’, i.e., 2.084 is lower than the critical value of 3.18 at 3 degrees of freedom (df) and hence it is not significant. Therefore, the null hypothesis cannot be rejected (p=0.129>0.05) at the 5% level of significance.

Fig. 2. Gram stain of culture isolates shows mixed growth with most bacillus species.

DISCUSSION

Titanium dioxide is a heterogeneous catalyst and is becoming a preferred choice as an antimicrobial coating for dental implants, orthopedic devices, and other health care facilities to prevent microbial growth. Several combinations have been reported; unfortunately, none of these methods have scientific reliability and integration. The present cross-sectional observational study was designed to evaluate the efficacy of TiO2 in preventing microbial growth in OTs. A wide range of studies have reported that photocatalysis is harmful to many organisms, including viruses, Gram +Ve / –Ve bacteria, algae, fungi, and protozoa, and is also effective in inactivating prions.4 TiO2 can kill Gram +Ve and Gram –Ve bacteria in water, air, and on surfaces of various materials.5 TiO2 photocatalysis is an economically feasible approach that uses water and hydrogen peroxide to fabricate an active TiO2 surface on titanium substrates. Under UV illumination, the organic substance is degraded by producing reactive oxygen species.6

Table (1):
Culture reports showing growth of various microbial floras at periodical interval.

Time period
Operation theatre 3
Operation theatre 4
End of 1st week
Bacillus Species
Candida species
Coagulase-negative staphylococcus
End of 2nd week
Staphylococcus species
Proteus Mirabilis
Micrococcus species
Staphylococcus species
Bacillus species
End of 1 month
Bacillus Species
Alcaligenes species
Staphylococcus aureus
Bacillus species
End of 2 month
Moraxella Species
Alcaligenes species
Staphylococcus aureus
Moraxella species
End of 3rd month
Moraxella Species
Staphylococcus aureus
Moraxella species
End of 6th month
Moraxella Species
Staphylococcus aureus
End of 9th month
Moraxella Species
Staphylococcus aureus

The amalgamation of the Ag matrix and TiO2 nanoparticles enhances the antibacterial effect by promoting Ag ion release and increasing the negative surface charge of the coatings.7 A study by Unosson stated that Ag- TiO2 can increase the photocatalytic properties, and incorporation of Ag into titanium biomaterials have effective antibacterial strategies.6 Visai et al. stated that photocatalytic sterilizing surfaces act in the absence of chemical material and electricity; instead, they require oxygen, light, and water. The surfaces of TiO2 are nontoxic and do not impact the environment negatively. This makes TiO2 substances a preferable option for the establishment of a health care setup.8

Table (2):
Prevalence of microbial growth in operation theatre 3 and 4.

Bacterial/Fungal grown Operation theatre 3 Operation theatre 4
Number of cultures Percentage of growth Number of cultures Percentage of growth
Moraxella 1 11.1% 2 14.2%
Bacillus Species 2 22.2% 2 14.2%
Staphylococcus 1 11.1% 6 42.8%
Micrococcus 2 22.2% 1 7.14%
Proteus 1 11.1% 0 0%
Alcaligenes 2 22.2% 0 0%
Candida Species 0 0% 1 7.14%
CoNS 0 0% 1 7.14%
Aspergillus 0 0% 1 7.14%

TiO2 surfaces have two important characteristic features, self-cleaning and self-disinfection, which act against bacteria. Degradation of organic substances by total oxidation prevents bacterial and biofilm adhesion on the surface of biomedical devices.9 Sunanda et al. stated that irradiated TiO2 surfaces kill bacteria in a three-step mechanism, such as cell wall invasion by reactive oxygen species, decomposition of the inner cytoplasmic membrane, and decomposition of toxic bacterial components.

In this study, the photo catalyst SmartCoat product is a liquid containing TiO2 nanoparticles as the main ingredient, and isopropyl alcohol and distilled water, were sprayed on biomedical devices in OT 3. Periodic culture isolates from both OT 3 (with SmartCoat) and OT 4 (without SmartCoat) showed minimal variation. Bacillus species (22.2%), Micrococcus (22.2%), and Alcaligenes (22.2%) were the most common isolated species on the OT 3 surface coated with SmartCoat. However, in OT 4, Staphylococcus (42.2%), Moraxella (14.2%), and Bacillus species (14.2%) were commonly isolated. Nine months after application of the SmartCoat product, OT 3 (with SmartCoat) showed low RLU and only Moraxella species was present. However, in OT 4, Staphylococcus, Moraxella, and fungi were observed.

Table (3):
Significance of differences in outcome of the antimicrobial effects.

  Paired Differences t df Sig.(2-tailed)
Mean±SD Std. Error Mean 95% CI difference
Lower Upper
Pair 1 After-After 9 months 2.122±2036.197 1018.098 -1118.29 5361.793 2.084 3 0.129

Chun et al. tested steel orthodontic wires coated with TiO2, which remained unchanged after adhesion tests, whereas uncoated wires increased their mass by 4.97%.10 A study by Chow Wai Leng et al. stated that samples from untreated surfaces with TiO2 and ad hoc samples were more likely to be culture positive (Methicillin-Resistant Staphylococcus aureus (9.2%) and gram negative bacteria (1.4%) and TiO2 did not influence positive culture results.11

CONCLUSION

Application of SmartCoat in OT 3 resulted in low RLU and growth of Moraxella species in the cultures. SmartCoat, a TiO2-based product, may not prevent microbial growth on biomedical devices in the OTs and may not be suitable for OTs unless it is supplemented by other OT sterilization procedures. The OT requires a maximum sterile environment to prevent sepsis and nosocomial infections. However, SmartCoat can be used in other healthcare facilities to minimize or prevent nosocomial infections.

Declarations

ACKNOWLEDGMENTS
We are indebted to the all faculties of Department of Anaesthesiology for their constant support.

CONFLICT OF INTEREST
The authors declare that there is no conflict of interest.

AUTHORS’ CONTRIBUTION
MU, MJ conceptualized the study. MU, TL did the data acquisition. MU, JK, MJ, TL  performed data analysis and interpretated the results, wrote the manuscript and did the revision. All authors read and approved the final version of the manuscript.

FUNDING
None.

ETHICS STATEMENT
The Study is approved by the Institutional Ethics Committee of Tomo Riba Institute of Health and Medical Sciences.

AVAILABILITY OF DATA
All datasets generated or analyzed during this study are included in the manuscript.

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