Calcium phosphate‐reinforced photosensitizer‐loaded polymer nanoparticles have been developed for photodynamic therapy. Chlorin e6 (Ce6)‐loaded core–shell–corona polymer micelles of poly(ethylene glycol)‐b‐poly(L ‐aspartic acid)‐b‐poly(L ‐phenylalanine) ( PEG-PAsp-PPhe ) were employed as template nanoparticles for mineralization with calcium phosphate (CaP). CaP deposition was performed by the electrostatic localization of calcium ions at the anionic PAsp middle shells and the subsequent addition of phosphate anions. CaP‐reinforced nanoparticles exhibited enhanced stability. The CaP mineral layer effectively inhibited Ce6 release from the Ce6‐loaded mineralized nanoparticles (Ce6‐NP‐CaP) at physiological pH value. At an acidic endosomal pH value of 5.0, Ce6 release was enhanced, owing to rapid dissolution of the CaP minerals. Upon irradiation of Ce6‐NP‐CaP‐treated MCF‐7 breast‐tumor cells, the cell viability dramatically decreased with increasing irradiation time. The phototoxicity of Ce6‐NP‐CaP was much higher than that of free Ce6. Non‐invasive optical‐imaging results indicated that Ce6‐NP‐CaP exhibited enhanced tumor specificity compared with free Ce6 and Ce6‐loaded non‐mineralized polymer nanoparticles (Ce6‐NP). 相似文献
A new dual soft‐template system comprising the asymmetric triblock copolymer poly(styrene‐b‐2‐vinyl pyridine‐b‐ethylene oxide) (PS‐b‐P2VP‐b‐PEO) and the cationic surfactant cetyltrimethylammonium bromide (CTAB) is used to synthesize hollow mesoporous silica (HMS) nanoparticles with a center void of around 17 nm. The stable PS‐b‐P2VP‐b‐PEO polymeric micelle serves as a template to form the hollow interior, while the CTAB surfactant serves as a template to form mesopores in the shells. The P2VP blocks on the polymeric micelles can interact with positively charged CTA+ ions via negatively charged hydrolyzed silica species. Thus, dual soft‐templates clearly have different roles for the preparation of the HMS nanoparticles. Interestingly, the thicknesses of the mesoporous shell are tunable by varying the amounts of TEOS and CTAB. This study provides new insight on the preparation of mesoporous materials based on colloidal chemistry. 相似文献
Strongly luminescent iridium(III) complexes, [Ir(C,N)2(S ,S )]+ ( 1 ) and [Ir(C,N)2(O,O)] ( 2 ), containing C,N (phenylquinoline), O,O (diketonate), or S,S (dithione) chelating ligands, have been characterized by X‐ray crystallography and DFT calculations. Their long phosphorescence lifetimes in living cancer cells give rise to high quantum yields for the generation of 1O2, with large 2‐photon absorption cross‐sections. 2 is nontoxic to cells, but potently cytotoxic to cancer cells upon brief irradiation with low doses of visible light, and potent at sub‐micromolar doses towards 3D multicellular tumor spheroids with 2‐photon red light. Photoactivation causes oxidative damage to specific histidine residues in the key proteins in aldose reductase and heat‐shock protein‐70 within living cancer cells. The oxidative stress induced by iridium photosensitizers during photoactivation can increase the levels of enzymes involved in the glycolytic pathway. 相似文献
Stable chromium, molybdenum, tungsten, manganese, rhenium, ruthenium, osmium, cobalt, rhodium, and iridium metal nanoparticles (M‐NPs) have been reproducibly obtained by facile, rapid (3 min), and energy‐saving 10 W microwave irradiation (MWI) under an argon atmosphere from their metal–carbonyl precursors [Mx(CO)y] in the ionic liquid (IL) 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([BMIm][BF4]). This MWI synthesis is compared to UV‐photolytic (1000 W, 15 min) or conventional thermal decomposition (180–250 °C, 6–12 h) of [Mx(CO)y] in ILs. The MWI‐obtained nanoparticles have a very small (<5 nm) and uniform size and are prepared without any additional stabilizers or capping molecules as long‐term stable M‐NP/IL dispersions (characterization by transmission electron microscopy (TEM), transmission electron diffraction (TED), and dynamic light scattering (DLS)). The ruthenium, rhodium, or iridium nanoparticle/IL dispersions are highly active and easily recyclable catalysts for the biphasic liquid–liquid hydrogenation of cyclohexene to cyclohexane with activities of up to 522 (mol product) (mol Ru)?1 h?1 and 884 (mol product) (mol Rh)?1 h?1 and give almost quantitative conversion within 2 h at 10 bar H2 and 90 °C. Catalyst poisoning experiments with CS2 (0.05 equiv per Ru) suggest a heterogeneous surface catalysis of Ru‐NPs. 相似文献
A folic acid targeted mixed micelle system based on co‐assembly of poly(ε‐caprolactone)‐b‐poly(methoxytri(ethylene glycol) methacrylate‐co‐N‐(2‐methacrylamido)ethyl folatic amide) and poly(ε‐caprolactone)‐b‐poly(diethylene glycol monomethyl ether methacrylate) is developed to encapsulate indocyanine green (ICG) for photothermal therapy and photodynamic therapy. In this study, the use of folic acid is not only for specific cancer cell recognition, but also in virtue of the carboxylic acid on folic acid to regulate the pH‐dependent thermal phase transition of polymeric micelles for controlled drug release. The prepared ICG‐loaded mixed micelles possess several superior properties such as a preferable thermoresponsive behavior, excellent storage stability, and good local hyperthermia and reactive oxygen species generation under near‐infrared (NIR) irradiation. The photototoxicity induced by the ICG‐loaded micelles has efficiently suppressed the growth of HeLa cells (folate receptor positive cells) under NIR irradiation compared to that of HT‐29, which has low folate receptor expression. Hence, this new type of mixed micelles with excellent features could be a promising delivery system for controlled drug release, effective cancer cell targeting, and photoactivated therapy. 相似文献
Injectable and biodegradable supramolecular hydrogel mPECT NP/α‐CDgel composed of high‐concentration nanoparticle dispersion (≤20% W/V) and α‐cyclodextrins (α‐CD) are prepared by a two‐level physical cross‐linking using amphiphilic block polymer methoxy poly(ethylene glycol)‐b‐poly(ε‐caprolactone‐co‐1,4,8‐trioxa[4.6]spiro‐9‐undecanone) (mPECT) and α‐CD. The gelation behavior depends on the concentration of nanoparticles and α‐CD. The viscoelasticity and shear thinning of mPECT NP/α‐CDgel are confirmed. In vitro hydrogel erosion is demonstrated to be mainly a concentration‐dependent dissociation process with general release of discrete mPECT nanoparticles about 50 nm that can be easily taken up by cells. The in vitro release behavior can be modulated by changing the concentration of nanoparticles or α‐CD. In vitro and in vivo cytotoxicity study demonstrates its biocompatibility and biosafety. Gel formation after subcutaneous injection is also confirmed and mPECT NP/α‐CDgel shows about 2 weeks retention time. This work validates the potential application for this supramolecular hydrogel in local and sustained delivery of nanoparticles.
A key to realizing the sustainable society is to develop highly active photocatalysts for selective organic synthesis effectively using sunlight as the energy source. Recently, metal‐oxide‐supported gold nanoparticles (NPs) have emerged as a new type of visible‐light photocatalysts driven by the excitation of localized surface plasmon resonance of Au NPs. Here we show that visible‐light irradiation (λ>430 nm) of TiO2‐supported Au NPs with a bimodal size distribution (BM‐Au/TiO2) gives rise to the long‐range (>40 nm) electron transport from about 14 small (ca. 2 nm) Au NPs to one large (ca. 9 nm) Au NP through the conduction band of TiO2. As a result of the enhancement of charge separation, BM‐Au/TiO2 exhibits a high level of visible‐light activity for the one‐step synthesis of azobenzenes from nitrobenzenes at 25 °C with a yield greater than 95 % and a selectivity greater than 99 %, whereas unimodal Au/TiO2 (UM‐Au/TiO2) is photocatalytically inactive. 相似文献
Thermally stable mesoporous TiO2/SiO2 hybrid films with pore size of 50 nm have been synthesized by adopting the polymeric micelle‐assembly method. A triblock copolymer, poly(styrene‐b‐2‐vinyl pyridine‐b‐ethylene oxide), which serves as a template for the mesopores, was utilized to form polymeric micelles. The effective interaction of titanium tetraisopropoxide (TTIP) and tetraethyl orthosilicate (TEOS) with the polymeric micelles enabled us to fabricate stable mesoporous films. By changing the molar ratio of TEOS and TTIP, several mesoporous TiO2/SiO2 hybrid films with different compositions can be synthesized. The presence of amorphous SiO2 phase effectively retards the growth of anatase TiO2 crystal in the pore walls and retains the original mesoporous structure, even at higher temperature (650 °C). These TiO2/SiO2 hybrid films are of very high quality, without any cracks or voids. The addition of SiO2 phase to mesoporous TiO2 films not only adsorbs more organic dyes, but also significantly enhances the photocatalytic activity compared to mesoporous pure TiO2 film without SiO2 phase. 相似文献
Nanocarriers are employed to deliver photosensitizers for photodynamic therapy (PDT) through the enhanced penetration and retention effect, but disadvantages including the premature leakage and non‐selective release of photosensitizers still exist. Herein, we report a 1O2‐responsive block copolymer (POEGMA‐b‐P(MAA‐co‐VSPpaMA) to enhance PDT via the controllable release of photosensitizers. Once nanoparticles formed by the block copolymer have accumulated in a tumor and have been taken up by cancer cells, pyropheophorbide a (Ppa) could be controllably released by singlet oxygen (1O2) generated by light irradiation, enhancing the photosensitization. This was demonstrated by confocal laser scanning microscopy and in vivo fluorescence imaging. The 1O2‐responsiveness of POEGMA‐b‐P(MAA‐co‐VSPpaMA) block copolymer enabled the realization of self‐amplified photodynamic therapy by the regulation of Ppa release using NIR illumination. This may provide a new insight into the design of precise PDT. 相似文献
Product selectivity of alkyne hydroamination over catalytic Au2Co alloy nanoparticles (NPs) can be made switchable by a light‐on/light‐off process, yielding imine (cross‐coupling product of aniline and alkyne) under visible‐light irradiation, but 1,4‐diphenylbutadiyne in the dark. The low‐flux light irradiation concentrates aniline on the catalyst, accelerating the catalytic cross‐coupling by several orders of magnitude even at a very low overall aniline concentrations (1.0×10?3 mol L?1). A tentative mechanism is that Au2Co NPs absorb light, generating an intense fringing electromagnetic field and hot electrons. The sharp field‐gradient (plasmonic optical force) can selectively enhance adsorption of light‐polarizable aniline molecules on the catalyst. The light irradiation thereby alters the aniline/alkyne ratio at the NPs surface, switching product selectivity. This represents a new paradigm to modify a catalysis process by light. 相似文献
In this work, we have successfully constructed a cobalt–oxo (CoIII4O4) cubane complex on polymeric carbon nitride (PCN) through pyridine linkage. The covalently grafted CoIII4O4 cubane units were uniformly distributed on the PCN surface. The product exhibited greatly enhanced photocatalytic activities for water oxidation under visible‐light irradiation. Further characterizations and spectroscopic analyses revealed that the grafted CoIII4O4 cubane units could effectively capture the photogenerated holes from excited PCN, lower the overpotential of oxygen evolution reaction (OER), and serve as efficient catalysts to promote the multi‐electron water oxidation process. This work provides new insight into the future development of efficient photocatalysts by grafting molecular catalysts for artificial photosynthesis. 相似文献
The extraction of rhodium and iridium with 4-(non-5-yl)pyridine (NP) was investigated. The rate of rhodium extraction increases with increasing concentration of NP and chloride ions. Spectroscopic studies indicate that the extracted species is an ion pair, RhCl3?6 3HNP+. Under the conditions of optimum Rh extraction ([Cl?]=3.7 M, [NP]=0.3 M, [H]=0.08 M), iridium is also extracted by NP with similar efficiency in the form of IrCl3?6 3HNP+. The use of hypophosphorous acid to labilize rhodium results in a better extraction of rhodium without significantly changing the extraction of iridium. The efficiency and kinetics of the rhodium extraction improve with increasing chloride concentration. For [Cl?] ? 3.7 M, [H3PO2]=2.5 M, [NP]=0.3 M and Ph ≈ 1.6, 82% of rhodium is extracted in 4 min and 95% in 30 min. 相似文献