Synthesis Of Semiconductor Photothermal Nanomaterials For Photothermal-and Chemotherapy

Photothermal therapy (PTT), as a minimally invasive therapeutic methodology, employs hyperthermia generated by photothermal agents from laser energy to kill cancer cells. In order to improve the therapeutic effects, it is necessary to explore high efficiency photothermal conversion nanomaterials. Meanwhile, further development of multifunctional nanocomposites is beneficial to integrate various technologies together for comprehensive treatments of cancer, overcoming the side effects of single way. Therefore, we firstly explore the preparation methods of silica yolk-shell structure as drug carrier; on the basis, develop Cu9S5@SiO2core-shell composite carrier for photothermal-and chemotherapy, then further explore the hydrophilic iron sulfide and molybdenum oxide as photothermal conversion material and investigate their effect of thermal ablation of cancer cells.1. Preparation of silica yolk-shell nanostructures (SYSNs) for effective cell imaging and drug deliverySilica-based yolk-shell nanostructures (SYSNs) are a potential platform of bioimaging and drug delivery for cancer diagnosis and therapy. Herein, a simple, flexible, green and controlled route to SYSNs is developed, in which structurally different silica core-shell-shell nanospheres are firstly prepared via a single step, and then their more porous interlayers are selectively etched by a mild agent (Na2CO3), resulting in the transformation of these silica core-shell-shell nanospheres to SYSNs. In this process, no complicated synthetic processes, special surfactants, corrosive etching agents or high temperature treatments are involved; moreover, the size, shell thickness, shape and void space of the SYSNs are controllable by simply tuning the synthetic parameters. For cell imaging and drug delivery, the surface of the formed SYSNs is functionalized with fluorescein isothiocyanate (FITC) and polyethylene glycol (PEG), which show excellent biocompatibility and possess sustained drug release properties. Furthermore, the drug loaded nanocomposites can induce breast cancer cell death efficiently, and exhibit a long-term cytotoxicity in vitro, indicating their promising properties as drug carriers for cell imaging and cancer chemotherapy.2. Preparation of Cu9S5@mSiO2core-shell composite nanoparticles for photothermal-and chemotherapiesCopper chalcogenides have been demonstrated to be a promising photothermal agent due to their high photothermal conversion efficiency, synthetic simplicity, and low cost. However, the large size, hydrophobic, less biocompatible characteristics associated with their synthetic processes hamper widely biological applications. An alternative strategy for improving hydrophilicity and biocompatibility is to coat the copper chalcogenide nanomaterials with silica shell. Herein, the rational preparation design results in successful coating mesoporous silica (mSiO2) on as-synthesized Cu9S5nanocrystals, forming Cu9S5@mSi02-PEG core-shell nanostructures. As-prepared Cu9S5@mSiO2-PEG core-shell nanostructures show low cytotoxicity and excellent blood compatibility, and are effectively employed for photothermal ablation of cancer cells and infrared thermal imaging. Moreover, anticancer drug of doxorubicin (DOX)-loaded Cu9S5@mSi02-PEG core-shell nanostructures show pH sensitive release profile and are therefore beneficial to delivery of DOX into cancer cells for chemotherapy. Importantly, the combination of photothermal and chemotherapies demonstrates better effects of therapy on cancer treatment than individual therapy approaches in vitro and in vivo.3. Preparation of hydrophilic FeS2nanocrystals for efficient ablation of cancer cellsTo promote the photothermal ablation (PTA) therapy and, in particular, to improve the lasers’ discrimination, it is necessary to cultivate high efficient photothermal coupling agents. Iron pyrite (FeS2) is a promising candidate photo-absorber material due to its earth abundance, high optical extinction, and infrared band gap (Eg=0.95eV). In the present, hydrophilic FeS2nanocrystals (NCs)(an average size of～20nm) have been prepared by a thermal decomposition reaction followed by surface modification. Encouragingly, the hydrophilic FeS2NCs exhibit strong near-infrared (NIR) photoabsorption and effectively convert laser energy into heat, compared to the our previously reported CU9S5NCs. Importantly, the efficient PTA of cancer cells by hydrophilic FeS2NCs under a808nm-laser irradiation has been demonstrated in vitro and in vivo for the first time. This study highlights FeS2NCs could serve as a promising platform of a new and excellent photothermal nanomaterials for NIR-Laser-Driven ablation of cancer cells. 4. Preparation and Characterization of hydrophilic molybdenum oxide nanomaterials for photothermal ablation of cancer cellsTo meet the requirements of molybdenum based nanomaterials as future photothermal therapy, a simple hydrothermal route has been developed for hydrophilic molybdenum oxide nanospheres and nanoribbons using molybdenum precursor and poly(ethylene glycol)(PEG). Firstly, molybdenum oxide nanomaterials prepared in the presence of PEG exhibit strong localized surface plasmon resonance (LSPR) absorption in the near infrared (NIR) region, compared with that of no PEG. Secondly, elevation of synthetic temperature leads to a gradual transformation of molybdenum oxide nanospheres into nanoribbons, entailing the evolution of an intense LSPR absorption in the NIR region. Thirdly, as-prepared molybdenum oxide materials coated with PEG possess hydrophilic property and thus can be directly used for biological application without additional post treatments. Moreover, molybdenum oxide nanoribbons as a model of photothermal agent can efficiently convert the980nm-wavelength laser energy into heat energy, and this localized hyperthermia produces the effective thermal ablation of cancer cells. Our preliminary results shed light on a promising use of molybdenum oxide based nanomaterials as a novel kind of effective photothermal nanomaterials.