DEVELOPMENT AND CHARACTERIZATION OF NOVEL SUB-COATINGS WITH POLYMORPHIC BROOKITE TITANIA NANOPARTICLES: ENHANCED UV/VIS PHOTOCATALYTIC ANTIBACTERIAL AND ANTICANCER PROPERTIES
ABSTRACT Nosocomial and community infections and biofilm formation from bacteria has increased significantly through adaptation combined with overuse of broad spectrum antibiotics. Because the world population continues to escalate, hospitals and long-term managed care will also escalate, thereby increasing transmission of infections, lowering patients\u27 quality of health. Another disease on the rise throughout the world is skin cancer. A treatment modality that would cause less deleterious effects on the patient would be ideal. These two seemingly different issues could be solved with one product. First an inexpensive, safe, and non-selective antimicrobial surface coating would enhance the hospital arena and a coating that would treat skin cancer like wearing a band-aid would be patient friendly. We proposed two novel sub-coatings containing polymorphic Titanium dioxide, Br200 and BrNMP. Titanium dioxide is versatile, non-selective, and degrades compounds through photocatalytic oxidation. The antibacterial sub-coating made of Poly(diallyldimethylammonium chloride) solution (PDDA) and Poly(4-styrenesulfonic acid) solution (PSS) in a 1:1 ratio of 0.1M PDDA/PSS as a 25 layer-by-layer coating on glass cover slips is known as the P sub-coating. It contains Nitrogen and Sulfur molecules that were associated via low temperature liquid deposition with Br200 or BrNMP Titania. XRD and XPS evaluations of these P sub-coatings containing the polymorphic Br200 and BrNMP confirmed a match with the original properties of the loose nanoparticles. P sub-coating with these Titania under long range ultraviolet light and visible light were evaluated for Methyl Orange oxidative-degradation to quantify photocatalytic activity. UVA irradiation of Br200 and BrNMP on the P sub-coating degraded Methyl Orange approximately two times faster than the same Titania on the control B sub-coating. The B sub-coating consisted of five mol of 3-glycidoxypropyl-trimethoxysilane mixed with 3 mol of Tetramethyl orthosilicate, prehydrolyzed with Ethanol and brought to pH 3 with Nitric acid. Light intensity, wavelength, surface material characteristics, and bacterial load affect efficiency of photo-oxidation. The super-hydrophilic nature of the polyelectrolyte-Titania coating may attract and enhance photo-oxidative activity due to bacterial adherence via hydrophilic fimbriae that attach to biotic and abiotic surfaces. Br200 demonstrated a stable working pH range including pH 3 to 4. The broad absorption edge of the polymorphic Brookite Titania Br200 and BrNMP enhanced by the N and S molecule surface interactions, and a narrowing of the band-gap, of the P sub-coating exhibited superior photocatalytic oxidative degradation on bacteria compared to the commercial P25 and vlp7000 Titania, or binder sub-coating with Titania. The polymorphic nature of Br200 and BrNMP may delay the electron/hole recombination centers due to electron transfer to different phases of crystallites. The LB sub-coating provided the polymorphic Titania with superior photocatalytic activity as compared to the P25 commercial product in vitro on HT-29 human colon cancer cells and HTB-67 Human Melanoma cells. The novel P sub-coating with polymorphic Brookite Titania can provide a low cost, effective method for decreased transmission of bacterial infections and biofilm formation in the healthcare arena and community setting. The novel format of using FDA approved liquid band-aid coated with Br200 non-selective Titania coating can provide lower pain and scarring in a topical format cancer treatment
