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Traditional contact lenses bring convenience for ophthalmic drug delivery. However, either as contact lenses or as drug carriers, traditional materials have still some drawbacks in the field. Therefore, a transparent film was designed and investigated for the application of therapeutic contact lenses. Chitosan (CS)/graphene oxide (GO) composite film and CS film were fabricated with acceptable transparent and tensile properties by simple casting flow method. Although swelling ratio of CS/GO composite film was higher than that of CS film with significant difference, both formed films had suitable swelling ratio for contact lens application. Both CS/GO composite film and CS film exhibited typical CS infrared characteristic peaks. CS/GO composite film had significant greater breaking strength than CS film, but its elongation at break was a little lower than CS film. Either CS/GO composite film or CS film exhibited good hydrophilic property with a contact angle of around 20 degree. Ofloxacin as a model drug was loaded into films by adsorption diffusion method. Loaded drug amount in CS/GO composite film was a little larger than that in CS film, but without significant difference. The drug release behaviors from CS/GO composite film or CS film were investigated and revealed that the loaded drug could be controlled to release in the first hour. Two kinds of cells were used to evaluate the biocompatibility of films by in vitro method. It was found that both CS/GO composite film and CS film could support human umbilical vein endothelial cell (HUVEC) growth. But for human epidermal fibroblasts (HSF) cells, CS/GO composite film could promote HSF cells growth and proliferation much better than CS film.

The application of azobenzene (AZO) as a kind of photo-switch is restricted by its excitation source, i.e., UV light. Hence, visible light-driven azobenzene-based photo-switching is needed and has been designed in the work. In order to forecast the optimal triggered wavelength, the electrostatic potential, theoretical UV-vis spectra, as well as the energy gap for focused structures was calculated to describe the energy and orbit status of the molecules by DFT. According to the theoretical optimization results, m-Methyl Red (m-MR) containing copolymer was successfully synthesized as a visible light-driven photo-switch. Further, for performance evaluation, the efficiency and effectiveness of different excitation wavelengths was firstly evaluated for the copolymer using m-MR and m-Methyl Red acrylic anhydride (m-MRAA) as the controls. Compared with m-MR and m-MRAA, the copolymer exhibited outstanding characteristics as a photo-switch according to its response–recovery behavior. At the same time, blue light proved to be the most efficient excitation light source. Moreover, the equilibrium response time and recovery time showed some dependence on the excitation wavelength. Secondly, the influence of the light intensity on the isomerization transition was investigated. A relatively low light density could lead to a relatively low degree of the final cis form and needed more equilibrium time for trans to cis transformation but showed little effect on the recovery process. Thirdly, repeatable on/off irradiation was used to evaluate the fatigue resistance of the copolymer. Good fatigue resistance without photobleaching was verified from the results. Fourthly, the influence of the solvent on visible light-driven isomerization was also evaluated. Finally, the synthesized copolymer still had the characteristic of a pH indicator with a critical point at pH 5.0 and exhibited an obvious fluorescent characteristic.

Synthesized polypeptide is attracting an increased interests due to its excellent biological characteristic and adjustable chemical properties in bio-related fields. But polypeptide itself has no switching properties, which is harmful to the development of its application as a control component. Herein, light-responsive poly(γ-benzyl-L-glutamate)s (PBLGs) is synthesized by a one-step NCA method using p-aminoazobenzene (m-AZO) and p-diaminoazobenzene (m-DAZO) as initiators. PBLGs exhibit amorphous characteristics with obvious Tg transition, which are 14°C for PBLG1 and 21°C for PBLG2. In order to forecast the structure-property information of PBLGs, theoretical UV-vis spectra as well as the energy gap between HOMO and LUMO is calculated by DFT calculation. Experimental results of UV-vis spectra exhibit similar characteristics to those of theorical UV-vis spectra except for the 40–50 nm red-shifting of absorbance peak. Furthermore, the absorbance intensities of PBLGs have a good linear relationship with their concentration, but their linearity range depending on concentration is completely different. Then, trans–cis transition under a different excitation source and cis–trans recovery in a dark environment are tracked in real-time by UV-vis spectra to evaluate the light response performances. It is found that UV light is the only effective excitation source for PBLG1, and blue light is another effective excitation source for PBLG2 besides UV light. Furthermore, the addition of alcohol and water as cosolvents has little effect on trans→cis transition in UV-light-excited systems, but it shortens recovery time of the cis→trans process in a dark environment. By contrast, the detectable isomerization process becomes unclear with the addition of alcohol in blue-light-excited system. Furthermore, either alcohol or water in solvents accelerate both the trans→cis and cis→trans process in a blue-light-excited system.

The photoisomerization of azobenzene (AZO) makes it a potential type of photoswitch for the field of chemical engineering. However, the lack of stability and photobleaching characteristics of reversible photoisomerization have restricted further application of AZO as a photoswitch. Therefore, we have designed two polymers containing the AZO domain as macromolecular photoswitches and investigated their switching performance. The hydrophilic monomers hydroxyethyl methylacrylate (HEMA) and N-vinyl-2-pyrrolidone (NVP) were chosen to copolymerize with the AZO monomer to form HEMA-AZO copolymer and HEMA-NVP-AZO terpolymer. The domain content was calculated by integration of the peaks in the 1H NMR spectrum. Real-time UV spectra of polymer solutions upon UV light irradiation confirmed quick and successful trans-to-cis transition for the AZO domain. In reverse, the operable and controllable recovery processes upon white light were also verified by real-time UV spectra. Furthermore, repeated irradiation by UV light and white light for 20 times was used to check their fatigue resistance and recyclability. Importantly, recovery behaviors for the two polymers could be adjusted by solvent property, environment temperature, and light intensity. Higher environment temperature or higher light intensity resulted in shortened recovery time. The influence of solvent was only slightly different for the two polymers. Nanoassemblies, which were formed by HEMA-NVP-AZO terpolymer and poly(β-cyclodextrin)/poly(α-cyclodextrin), exhibited similar controllable switching performance to the pure polymer. In brief, the effectiveness and efficiency of the polymers as photoswitches have been confirmed by results in this work.

Light-responsive materials have attracted increasing interest in recent years on account of their adjustable on-off properties upon specific light. In consideration of reversible isomerization transition for azobenzene (AZO), it was designed as a light-responsive domain for nanoparticles in this research. At the same time, the interaction between AZO domain and β-cyclodextrin (β-CD) domain was designed as a driving force to assemble nanoparticles, which was fabricated by two polymers containing AZO domain and β-CD domain, respectively. The formed nanoparticles were confirmed by Dynamic Light Scattering (DLS) results and Transmission Electron Microscope (TEM) images. An obvious two-phase structure was formed in which the outer layer of nanoparticles was composed of PCD polymer, as verified by 1HNMR spectroscopy. The efficient and effective light response of the nanoparticles, including quick responsive time, controllable and gradual recovered process and good fatigue resistance, was confirmed by UV-Vis spectroscopy. The size of the nanoparticle could be adjusted by polymer ratio and light irradiation, which was ascribed to its light-response property. Nanoparticles had irreversibly pH dependent characteristics. In order to explore its application as a nanocarrier, drug loading and in vitro release profile in different environment were investigated through control of stimuli including light or pH value. Folic acid (FA), as a kind of target fluorescent molecule with specific protein-binding property, was functionalized onto nanoparticles for precise delivery for anticancer drugs. Preliminary in vitro cell culture results confirmed efficient and effective curative effect for the nanocarrier on MCF-7 cells.

The family of graphene has attracted increasing attention on account of their large specific surface area and good mechanical properties in the biomedical field. However, some characteristics like targeted delivery property and drug delivery capacity could not satisfy the need of a drug carrier. Herein, a graphene oxide (GO) nanocarrier was designed by modification of a folic acid (FA) derivative and a β-cyclodextrin (β-CD) derivative in order to improve two properties, respectively. In the first step, reactive or crosslinkable FA and aldehydic β-CD (β-CD-CHO) were designed and synthesized for further modification. In the second step, synthesized functional molecules were coupled onto GO sheets one by one to obtain the GO nanocarrier. IR spectra and XRD results were used to identify the chemical and structural information before and after modification for the GO nanocarrier. The final GO nanocarrier exhibited a typical thin wrinkled sheet morphology of the GO sheet without any influence by two functional molecules. Finally, in vitro evaluation was used to clarify the drug loading and controlling capacity of the nanocarrier as a drug delivery system. The results revealed that the GO nanocarrier had a better CPT loading capacity and showed better controllability for CPT release.