According to previous reports, low pH-triggered nanoparticles were considered to be excellent carriers for anticancer drug delivery, for the reason that they could trigger encapsulated drug release ...at mild acid environment of tumor. Herein, an acid-sensitive β-cyclodextrin derivative, namely, acetalated-β-cyclodextrin (Ac-β-CD), was synthesized by acetonation and fabricated to nanoparticles through single oil-in-water (o/w) emulsion technique. At the same time, camptothecin (CPT), a hydrophobic anticancer drug, was encapsulated into Ac-β-CD nanoparticles in the process of nanoparticle fabrication. Formed nanoparticles exhibited nearly spherical structure with diameter of 209 ± 40 nm. The drug release behavior of nanoparticles displayed pH dependent changes due to hydrolysis of Ac-β-CD. In order to overcome the disadvantages of nanoparticle and broaden its application, injectable hydrogels with Ac-β-CD nanoparticles were designed and prepared by simple mixture of nanoparticles solution and graphene oxide (GO) solution in this work. The injectable property was confirmed by short gelation time and good mobility of two precursors. Hydrogels were characterized by dynamic mechanical test and SEM, which also reflected some structural features. Moreover, all hydrogels underwent a reversible sol-gel transition in alkaline environment. Finally, the results of in vitro drug release profile indicated that hydrogel could control drug release or bind drug inside depending on the pH value of released medium.
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•The twisted azo units can cause trans→cis isomerization to be driven by visible light.•The twisted geometry increases the dipole and π-conjugation extent of azo in vacuum.•The ...twisted geometry affects the ICT of D-π-A azo derivative in solutions.
Most azobenzene derivatives require the use of ultraviolet light for photoisomerization, this limits the utilization of them in biological systems, energy-storing material fields and so on. It’s useful to develop azo-based photo-switches triggered with visible light. Three synthesized azobenzene derivatives (tetra-o-methoxyl-4,4′-diacetamidoazobenzene, 5,6-dihydrodibenzoc,g1,2diazocine and 3,5-dimethyl-bisazo) who can be driven by visible light were studied by DFT calculations in this article. We found that they all have the same structural features of the twisted azobenzene trans geometries. The planarity of azobenzene, which can be reflected by ϕCNNC (the dihedral angle connecting the azo moiety and two phenyl rings) and θCCNN (the dihedral angle connecting the azo moiety and one of the phenyl rings). To better understand the relationship between structure and optical properties, absorption spectra of azobenzene in vacuum as the function of ϕCNNC and θCCNN rotation were investigated by using DFT and TDDFT methods. Calculations demonstrated that distorting ϕCNNC and θCCNN can both result in the red shift of the absorption bands to the visible light wavelength, and ϕCNNC has a greater impact than θCCNN. Furthermore, the influence of twisted structure on the absorption band of 4-(4-aminophenylazo) nitrobenzene (a D-π-A type azobenzene derivative) in DMSO solution was also studied. Our results indicated that both ϕCNNC and θCCNN(NH2) rotation decreased the HOMO–LUMO gap, causing a red shift of the S0→S1 absorption band. However, the θCCNN(NO2) rotation increased the HOMO–LUMO gap slightly, resulting in a little blue shift of the whole bands. This work may provide useful theoretical foundation for fabricating of new visible light driven azobenzene-based photo-switches.
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.
Quantum dots (QDs) are zero dimensional nanomaterials and promising materials in the fluorescent label, LED display, metal ions sensor, catalysis and so on. ZnO QDs are one kind of ideal QDs, due to ...their non-poisonous, easy prepared, plentiful, economical properties. The visible light emission colour and quantum yields of ZnO QDs is determined by their band structures and defect structures. Main method to adjust the optical performance is controlling the particle sizes, band structures and defect structures by adjusting synthesis method and doping. Therefore, it is important to investigate the mechanisms of particle growth and defects variation. In this paper, a sol–gel method were employed to synthesize stable ZnO QDs used in fluorescence labeling and solar cells. Effects of reactants concentration, material ratio and reaction time on particle sizes and defects structures of ZnO QDs synthesized by sol–gel method were studied. Changing the synthesis process of ZnO QDs can adjust their photoluminescence defects structures and particle sizes. The ZnO QDs synthesized with c(Zn
2+
) = 0.1 mol L
− 1
, n(OH
−
):n(Zn
2+
) = 2:1, for 1.5 h reaction showed the highest photoluminescence quantum yields (40%) with green emission under 359 nm UV-light excitation. The visible light emission of the ZnO QDs synthesized with c(Zn
2+
) = 0.025 mol L
− 1
, n(OH
−
):n(Zn
2+
) = 3:1, for 1.5 h min is blue-green colour excited under 337 nm.
Magnetic poly(styrene methyl methacrylate)/Fe
3O
4 nanospheres with ester groups were prepared by a modified one-step mini-emulsion polymerization in the presence of Fe
3O
4 ferrofluids. The effects ...of monomer dose, surfactant content, ferrofluid concentration and initiator content on the particle characteristics such as the size, morphology and magnetic properties were investigated by Fourier-transform infrared spectroscopy, transmission electron microscopy, thermogravimetric analysis and vibrating sample magnetometer. The results indicated that magnetic nanospheres were superparamagnetic with high saturation magnetization of 51.0
emu/g and corresponding magnetite content of 61.5
wt%. Subsequently, magnetic nanospheres with carboxyl and amino groups were also obtained by hydrolysis and ammonolysis reaction. These magnetic nanospheres with multifunctional groups have biomedical applications.
► Facile way of synthesis of ester-functionalized superparamagnetic nanospheres. ► Wide scope of synthesis for other kinds of functional magnetic polymer nanospheres. ► The modification bilayer is the key factor controlling the encapsulation of products. ► Potential application of biomedical field.
•TiN-Al2O3-Cr gradient layer is introduced to tailor residual stress of CZTSSe.•60 nm sputtered gradient layer contributes the best heterojunction characteristic.•Gradient layer introduced device ...exhibits more satisfying bending stability.
In an effort to promote the mechanical endurance of flexible Cu2ZnSn(S,Se)4 (CZTSSe) solar cells, a convenient and effective strategy for introducing a TiN-Al2O3-Cr gradient layer is proposed, which can effectively tailor the residual stress and improve the heterojunction characteristic of solar cell. Benefitted from the optimum TiN-Al2O3-Cr gradient layer with 60 nm, CZTSSe presents a released residual stress of −3.33 GPa and an optimized heterojunction characteristic with the CBO of −0.28 eV. Furthermore, the PCE of flexible device is remarkably improved from 3.31 % to 5.01 %, which can maintain 85 % of the original efficiency after harsh bending. The proposed gradient layer strategy may pave a thriving way for congener flexible and portable cells.
Theoretical investigation on a series of oligothienoacenes has been carried out at the B3LYP/6-31G* level by considering the influence of the external electric field. With the electric field ...increasing, the carbon–carbon single bonds become shorter and the carbon–carbon double bonds become longer, resulting in a better conjugation. Due to the different electron density, the charge mobility of the sulfur is more obvious than that of the carbon. The highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) gap decreases with the EF intensity increasing. The applied EF also changes the spatial distribution of the molecular orbits: LUMO and several higher orbitals shift to the high potential side, whereas HOMO and several lower ones shift to the low potential side. All these features behave more pronounced with increasing conjugated chain length.
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