Photoinduced Release Research Articles

Ortho-Nitrobenzyl alcohol based two-photon excitation controlled drug release system

Controlled drug delivery is highly desired for many medicinal cases where time and spatial dependency is required. The present paper provides a promising but also simple molecular architecture for photoinduced release of chemical compounds with primary amines based on one-and two-photon absorption. Silane coupling to the surface and biotin/streptavidin chemistry ensure the stability of the system.

The effect of nitro substitution on the photochemistry of benzyl benozhydroxamate: Photoinduced release of benzohydroxamic acid

Abstract The redox congener of the important signaling agent nitric oxide (NO), nitroxyl or nitrosyl hydride (HNO) has also been demonstrated to induce distinct physiological effects. The aim of this study was to determine if benzohydroxamic acid, which was selected as a stable model compound of HNO donors, could be released by the o -nitrobenzyl photolabile protecting group (PPG) in a wavelength-dependent manner. It was expected that selective irradiation of the o -nitrobenzyl chromophore would favor the release of benzohydroxamic acid over undesired products associated with N–O bond cleavage. Quantum yields for the release of benzohydroxamic acid protected by the o -nitrobenzyl PPG increased at longer wavelengths, with a concomitant decrease in the yield of minor products. Through the use of triplet photosensitizers, triplet quenchers, computational methods, and the position of the nitro substituent, insights into the nature of the mechanism were suggested.

Biocompatible Micelles Based on Comb‐like PEG Derivates: Formation, Characterization, and Photo‐responsiveness

A novel comb-like derivative CPEG-g-DNQ was prepared by incorporating light responsive 2-diazo-1,2-naphthoquinone (DNQ) groups into the structure of comb-like poly(ethylene glycol) (CPEG). DLS and TEM results showed that CPEG-g-DNQ self-assembled into spherical micelles with an average size of about 135 nm in water. Upon exposure to light, the micelles could be disrupted because of the conversion of hydrophobic DNQ to hydrophilic 3-indenecarboylic acid. Additionally, hydrophobic coumarin 102 was successfully loaded into the micelles and photo-induced ON-OFF release was demonstrated by fluorescence spectroscopy. MTT assay revealed that the micelles are biocompatible. These photo-responsive micelles might have great potential for controlled release of hydrophobic drugs.

Photoinduced oxygen release and persistent photoconductivity in ZnO nanowires

Photoconductivity is studied in individual ZnO nanowires. Under ultraviolet (UV) illumination, the induced photocurrents are observed to persist both in air and in vacuum. Their dependence on UV intensity in air is explained by means of photoinduced surface depletion depth decrease caused by oxygen desorption induced by photogenerated holes. The observed photoresponse is much greater in vacuum and proceeds beyond the air photoresponse at a much slower rate of increase. After reaching a maximum, it typically persists indefinitely, as long as good vacuum is maintained. Once vacuum is broken and air is let in, the photocurrent quickly decays down to the typical air-photoresponse values. The extra photoconductivity in vacuum is explained by desorption of adsorbed surface oxygen which is readily pumped out, followed by a further slower desorption of lattice oxygen, resulting in a Zn-rich surface of increased conductivity. The adsorption-desorption balance is fully recovered after the ZnO surface is exposed to air, which suggests that under UV illumination, the ZnO surface is actively "breathing" oxygen, a process that is further enhanced in nanowires by their high surface to volume ratio.

Optical waveguides for the evanescent wave-induced cleavage of photolabile linker compounds

Functional surfaces and especially the control of surface properties depending on external parameters such as light illumination have gained increasing importance in the last few years. We present the characterization of polymers from the cycloolefin (co)polymer class (COC/COP) functionalized with an aminosilane as a basis for the further immobilization of compounds. In a first step, an assay using AlexaFluor®647 fluorescent dye was used to assess surface homogeneity and reproducibility. A coefficient of variation of less than 15% for dot-to-dot and less than 25% for chip-to-chip could be achieved. The same amino-functionalized surfaces were then used to immobilize a biotinylated photolabile linker compound, binding AlexaFluor®647-labeled streptavidin. The linker was photocleaved with high efficiency at λ = 365 nm and P = 0.15 mW/cm(2). Fluorescence measurements show that polymers of the COC/COP class can be used as versatile surfaces for the photoinduced release of compounds immobilized via photolabile linkers.

An Anthracene Based Photoswitchable Dioxo‐Tetraaza Ligand Selective for CuII and Capable of Photochemical pKa Modulation

AbstractTwo anthracene fragments were added to a linear dioxotetramine ligand in order to exploit a [4πs+4πs] photocycloaddition reaction and obtain a photoswitchable selective receptor for CuII, whose cavity (and binding abilities) can be closed on command. Moreover, it was demonstrated that this new ligand, N,N′‐bis{2‐[(anthracen‐9‐ylmethyl)amino]ethyl}malonamide (LH2), can also be used for the photoinduced release of protons in aqueous solution, as a result of photoinduced pKa modulation.

Photoinduced ligand release in a ruthenium(ii)-cobalt(iii) heterodinuclear system

Two Ru(II)-Co(III) heterodinuclear complexes have been synthesised as model complexes for photoactivated cytotoxins. Photoinduced ligand release has been demonstrated and the rate shown to depend on dioxygen concentration. Emission lifetimes and quantum yields are reported. These results validate the concept and justify further work to synthesise systems containing cytotoxic ligands.

Disruption of reverse micelles and release of trapped ribonuclease A photochemically induced by Malachite Green leuconitrile derivative

Photoinduced disruption of a sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reverse micelle is triggered by a Malachite Green leuconitrile derivative (MGL). UV irradiation of MGL solubilized in an AOT-water-chloroform mixture creates a cationic surfactant that interacts electrostatically with the anionic AOT. We investigated the disruption of the reverse micelle by using proton nuclear magnetic resonance spectroscopy and found that UV irradiation of MGL decreases the number of water molecules solubilized in the interior of the AOT reverse micelles. Furthermore, the photoinduced disruption of the reverse micelle is shown to release ribonuclease A, which is trapped in the water in the interior of the AOT reverse micelle. This photoinduced release may offer a desirable transport system of biopolymers.

Involvement of protons in the ion transport cycle of Na+,K+-ATPase

The effect of pH on electrogenic sodium transport by the Na+ ,K+ -ATPase has been studied. Experiments were carried out by admittance recording in a model system consisting of a bilayer lipid mem­ brane with adsorbed membrane fragments containing purified Na+ ,K+ -ATPase. Changes in the membrane admittance (capacitance and conductance increments in response to photo-induced release of ATP from caged ATP) were measured as function of AC voltage frequency, sodium ion concentration, and pH. In solu­ tions containing 150 m M Na+, the frequency dependence of capacitance increments was not significantly dependent on pH in the range between 6 and 8. At a low NaCl concentration (3 mM), the capacitance incre­ ments at low frequencies decreased with the increasing pH. In the absence ofNaCl, the frequency-dependent capacitance increment at low frequencies was similar to that measured in the presence of 3 mM NaCI. These results may be explained by involvement of protons in the Na+, K+ -ATPase pump cycle, i.e., electroneutral exchange of sodium ions for protons under physiological conditions, electrogenic transport of sodium ions at high pH, and electrogenic transport of protons at low concentrations (and in the absence) of sodium ions.

A Polymeric Drug Depot Based on 7‐(2′‐Methacryloyloxyethoxy)‐4‐methylcoumarin Copolymers for Photoinduced Release of 5‐Fluorouracil Designed for the Treatment of Secondary Cataracts

AbstractThe synthesis of a polymeric, photoresponsive drug‐delivery system on the basis of 4‐methylcoumarin‐side‐chain‐functionalized methacrylic copolymers with different degrees of functionalization is reported. Drug‐release experiments in solution indicated a maximum release of 22 µg of 5‐fluorouracil per 1 mg of polymer. Polymer analogous photochemical drug immobilization does not lead to observable intermolecular cross‐linking. Miscibility experiments with PMMA suggest that the bulk polymerization of homogeneous, transparent polymer sheets for intraocular lens fabrication, using MMA as the matrix monomer and incorporating the polymer‐drug conjugates as a functional component, is possible.magnified image

Oxidative Cyclization of a Phenolic Schiff Base and Synthesis of a Cyclometalated Ruthenium Nitrosyl Complex: Photoinduced NO Release by Visible Light

The reactivity of sigma-arylruthenium cyclometallate [Ru(L(SB1))(PPh(3))(2)Cl] [1; L(SB1)H(2) = 4-methyl-2-(4-nitrobenzylideneamino)phenol] with nitric oxide (NO) gave rise to nitrosylation at the metal center, ring nitration, and oxidative cyclization, affording benzoxazole derivative formation. The molecular structure of the resultant nitrosyl complex, [Ru(L(PB1))(PPh(3))(2)(NO)Cl](ClO(4)) [2; L(PB1)H = 5-methyl-7-nitro-2-(4-nitrophenyl)benzoxazole] was determined, and a different sigma-arylruthenium cyclometallate was characterized in which the benzoxazole derivative was found to be coordinated to the metal center. The crystal structure and IR and NMR spectral data confirmed the formation of a diamagnetic {RuNO}(6) species with a S = 0 ground state and a {Ru(II)NO(+)}(6) description of the {RuNO}(6) moiety. Coordinated NO in the resultant complex 2 was photolabile under visible light and was transferred to reduced myoglobin.

Remote‐Control Photorelease of Caged Compounds Using Near‐Infrared Light and Upconverting Nanoparticles

Cage fighter: Lanthanide-doped upconverting nanoparticles convert near-infrared light into ultraviolet light, which drives the photoinduced release of a “caged” species on the nanoparticle surface. This approach overcomes the problem that low-energy light is necessary for penetrating deeper into tissue without damage but cannot be used to directly trigger important organic photochemical reactions.

Photoinduced drug release from thermosensitive AuNPs-liposome using a AuNPs-switch

A thermosensitive liposome with embedded AuNPs in a bilayer was prepared using supercritical CO(2). The AuNPs-liposome can absorb a certain wavelength light, convert optical energy into heat, induce phase transition, and release drug. The results show that drug release from the liposome is due to the photothermic effects inducing phase transition of the liposome rather than destruction of the liposome structure.

Alternative photoinduced release of HNO or NO from an acyl nitroso compound, depending on environmental polarity

A hydrophilic hetero-Diels-Alder cycloadduct was synthesized as a novel photocontrollable donor of reactive nitrogen species. Production of either nitric oxide (NO) or nitroxyl (HNO) was photoinduced from this compound, depending on the environmental polarity.

Photo-induced release of active plasmid from crosslinked nanoparticles: o-nitrobenzyl/methacrylate functionalized polyethyleneimine

To facilitate DNA packaging and photolytic release, o-nitrobenzyl and methacrylate functionalized PEI (P10A) was synthesized for condensing DNA into nanoparticles as small as 160 nm after radical polymerization with initiator. The gene expression following delivery of uncross-linked P10A/DNA was unchanged by photoirradiation of cells. However, exposure to photo-irradiation caused a 3-fold increase in gene expression in cells transfected with cross-linked P10A/DNA. These polyplexes were designed to mimic viral particles that condense and protect DNA while allowing subsequent triggered release of DNA.

Magnetically Guided TiO2 Nanotubes for Site Selective Photoinduced Drug Release

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Photoinduced release of active proteins from TiO 2 surfaces

The present work reports on enzyme attachment on and photoinduced release from TiO 2 surfaces. TiO 2 layers (amorphous and anatase) were modified with 3-aminopropyltriethoxysilane (APTES), followed by attachment of vitamin C and horseradish peroxidase (HRP). Using step by step XPS characterization and vis-spectroscopy we show that upon UV illumination the linker chain to the protein can be cut, releasing active HRP into the environment. The head silane group remains attached to the TiO 2 surface. The kinetics of this photoinduced release is significantly faster for the anatase form of TiO 2 compared with amorphous material. The results indicate that UV induced chain scission represents a very versatile tool for payload release from TiO 2 surfaces.

Photoinduced Intracellular Controlled Release Drug Delivery in Human Cells by Gold-Capped Mesoporous Silica Nanosphere

A gold nanoparticle (AuNP)-capped mesoporous silica nanosphere (MSN)-based intracellular drug delivery system (PR-AuNPs-MSN) for the photoinduced controlled release of an anticancer drug, paclitaxel, inside of human fibroblast and liver cells was synthesized and characterized. We found that the mesopores of MSN could be efficiently capped by the photoresponsive AuNPs without leaking the toxic drug, paclitaxel, inside of live human cells. This "zero premature release" characteristic is of importance for delivery of toxic drugs in chemotherapy. Furthermore, we demonstrated that the cargo-release property of this PR-AuNPs-MSN system could be easily controlled by low-power photoirradiation under biocompatible and physiological conditions. We envision that our results would play a significant role in designing new generations of carrier materials for intracellular delivery of a variety of hydrophobic toxic drugs.

Photoresponsive Cyclodextrin‐Covered Nanocontainers and Their Sol‐Gel Transition Induced by Molecular Recognition

Springing the trap: Cyclodextrin-covered mesoporous silica nanoparticles with photocleavable linkers exhibit photoinduced release characteristics and a sol-gel transition that is induced by molecular recognition (see picture). Upon exposure to UV light, the guest molecules were released from the pore by removal of the CD "gatekeeper", which was linked on the surface of the silica nanoparticle through a photocleavable o-nitrobenzyl ester moiety.

Femtosecond to Subnanosecond Multistep Calcium Photoejection from a Crown Ether‐Linked Merocyanine

Photoinduced calcium release from the crown ether-linked merocyanine DCM-crown is reexamined by femtosecond transient absorption spectroscopy with sub-100 fs time resolution. Photodisruption of the bond linking the cation to the nitrogen atom shared by the crown and the chromophore is found to take place in 130 fs. Confirming our previous reports, the photoinduced intraligand charge transfer is observed in the picosecond regime but kinetics involving three-components (1 ps, 8 ps and 77 ps), together with a 56 ps stimulated-emission time-resolved red shift, are found in the present study. Both delayed intraligand charge transfer and cation release are assumed to occur in this time range due to repulsion effects between the positively charged nitrogen of the crown ether moiety and the cation. In the subnanosecond regime, a 670 ps time-resolved red shift of the stimulated-emission spectrum of the charge-transfer state, similar to the shift previously observed with Sr(2+), demonstrates the motion of the cation away from the crown to the bulk. A thorough examination of the present data allows us to conclude that calcium ion is photoejected to the bulk in a multistep process.