Blue Light Activated Photocatalytic Protein Decomposition on Anatase Modifications

Method: Quartz crystals pre-coated with titanium, pure anatase (Ana) or nitrogen doped anatase (Ana-N) served as testing samples. The degree of photocatalytic decomposition of HSA (1 mg ml^-1) and human sterile saliva on these samples were analyzed by a quartz crystal microbalance system (QCM-D; Q-Sense, Sweden) under two kinds of light irradiation: UV-A (382 nm, 25 mW cm^-2; Hoenle, Germany), LED (405 nm, 1050 mW cm^-2; Hoenle, Germany). Besides, for testing HSA decomposition, a clinical LED lamp (380-515 nm, maximum peak at 460 nm, 650 mW cm^-2; Ivoclar Vivadent, Germany) was applied. Decomposition data were statistically analyzed by pairwise comparison of means by student’s t-test (p≤0.05).

Result: Under UV-A, nearly complete decomposition (>75%) of adsorbed HSA and saliva protein was observed on Ana and Ana-N. Both modifications also degraded protein (>60%) under blue light (>400 nm). Even for the clinical LED, decomposition (<30%) of protein on anatase samples was also induced, although the kinetics of degradation was slow here. Under each irradiation regime, decomposition on both modifications significantly exceeded the Ti reference (p≤0.05).

Conclusion: The photocatalytic protein decomposition on anatase surfaces can be induced under UV-A and blue light irradiation. Observations indicated that nitrogen doped anatase might improve this decomposition upon blue light.

Supported by the ITI foundation (Basel, Switzerland)