Melanoma is one of the most aggressive and lethal form of cancer. Photodynamic therapy (PDT) is a clinically approved technique for cancer treatment, including non-melanoma skin cancer. However, the most of conventional photosensitizers are of low efficacy against melanoma due to the possible dark toxicity at high drug concentrations, melanin pigmentation, and induction of anti-oxidant defense mechanisms. In the current research we propose non-toxic flavin mononucleotide (FMN), which is a water-soluble form of riboflavin (vitamin B2) as a promising agent for photodynamic therapy of melanoma. We demonstrated selective accumulation of FMN in melanoma cells in vivo and in vitro in comparison with keratinocytes and fibroblasts. Blue light irradiation with dose 5 J/cm 2 of melanoma cells pre-incubated with FMN led to cell death through apoptosis. Thus, the IC 50 values of human melanoma A375, Mel IL, and Mel Z cells were in a range of FMN concentration 10–30 µM that can be achieved in tumor tissue under systemic administration. The efficiency of reactive oxygen species (ROS) generation under FMN blue light irradiation was measured in single melanoma cells by a label-free technique using an electrochemical nanoprobe in a real-time control manner. Melanoma xenograft regression in mice was observed as a result of intravenous injection of FMN followed by blue-light irradiation of tumor site. The inhibition of tumor growth was 85–90% within 50 days after PDT treatment.

Three-dimensional (3D) rapid prototyping technology based on near-infrared light-induced polymerization of photocurable compositions containing upconversion nanomaterials has been explored. For this aim, the rationally-designed core/shell upconversion nanoparticles NaYF4:Yb3+,Tm3+/NaYF4, with the distinct ultraviolet-emitting lines and unprecedentedly high near-infrared to ultraviolet conversion efficiency of have been used. The upconverted ultraviolet photons were capable to efficiently activate photoinitiators contained in light-sensitive resins under moderate intensities of NIR excitation below 10 W cm−2 and induce generation of radicals and photopolymerization in situ. Near infrared-activated polymerization process, both at the millimeter and sub-micron scales, was investigated. Polymeric macro- and microstructures were fabricated by means of near infrared laser scanning photolithography in the volume of liquid photocurable compositions with focused laser light at 975 nm wavelength. Examination of the polymerization process in the vicinity of the nanoparticles shows strong differences in the rate of polymer shell growth on flat and edge nanoparticle sides. This phenomenon mainly defines the resolution of the demonstrated near infrared - ultraviolet 3D printing technology at the micrometer scale level.