We demonstrate a novel strategy enabling the use of a continuous-wave diode near-infrared (NIR) laser to disrupt block copolymer (BCP) micelles and trigger the release of their "payloads". By encapsulating NaYF(4):TmYb upconverting nanoparticles (UCNPs) inside micelles of poly(ethylene oxide)-block-poly(4,5-dimethoxy-2-nitrobenzyl methacrylate) and exposing the micellar solution to 980 nm light, photons in the UV region are emitted by the UCNPs, which in turn are absorbed by o-nitrobenzyl groups on the micelle core-forming block, activating the photocleavage reaction and leading to the dissociation of BCP micelles and release of co-loaded hydrophobic species. Our strategy of using UCNPs as an internal UV or visible light source upon NIR light excitation represents a general and efficient method to circumvent the need for UV or visible light excitation that is a common drawback for light-responsive polymeric systems developed for potential biomedical applications.

Using a photosensitive hybrid hydrogel loaded with upconversion nanoparticles (UCNPs), we show that continuous-wave near-infrared (NIR) light (980 nm) can be used to induce the gel-sol transition and release large, inactive biomacromolecules (protein and enzyme) entrapped in the hydrogel into aqueous solution "on demand", where their bioactivity is recovered. This study is a new demonstration and development in harnessing the unique multiphoton effect of UCNPs for photosensitive materials of biomedical interest.

Only one type of lanthanide-doped upconverting nanoparticle (UCNP) is needed to reversibly toggle photoresponsive organic compounds between their two unique optical, electronic, and structural states by modulating merely the intensity of the 980 nm excitation light. This reversible "remote-control" photoswitching employs an excitation wavelength not directly absorbed by the organic chromophores and takes advantage of the fact that designer core-shell-shell NaYF(4) nanoparticles containing Er(3+)/Yb(3+) and Tm(3+)/Yb(3+) ions doped into separate layers change the type of light they emit when the power density of the near-infrared light is increased or decreased. At high power densities, the dominant emissions are ultraviolet and are appropriate to drive the ring-closing, forward reactions of dithienylethene (DTE) photoswitches. The visible light generated from the same core-shell-shell UCNPs at low power densities triggers the reverse, ring-opening reactions and regenerates the original photoisomers. The "remote-control" photoswitching using NIR light is as equally effective as the direct switching with UV and visible light, albeit the reaction rates are slower. This technology offers a highly convenient and versatile method to spatially and temporally regulate photochemical reactions using a single light source and changing either its power or its focal point.

Photothermal release of DNA from gold nanoparticles either by thermolysis of the Au-S bonds used to anchor the oligonucleotides to the nanoparticle or by thermal denaturation has great therapeutic potential, however, both processes have limitations (a decreased particle stability for the former process and a prohibitively slow rate of release for the latter). Here we show that these two mechanisms are not mutually exclusive and can be controlled by adjusting laser power and ionic strength. We show this using two different double-stranded (ds)DNA-nanoparticle conjugates, in which either the anchored sense strand or the complementary antisense strand was labeled with a fluorescent marker. The amounts of release due to the two mechanisms were evaluated using fluorescence spectroscopy and capillary electrophoresis, which showed that irradiation of the decorated particles in 200 mM NaOAc containing 10 mM Mg(OAc)(2) with a pulsed 532 nm laser operating at 100 mW favors denaturation over Au-S cleavage to an extent of more than six-to-one. Due to the use of a pulsed laser, the process occurs on the order of minutes rather than hours, which is typical for continuous wave lasers. These findings encourage continued research toward developing photothermal gene therapeutics.

Near-infrared (NIR) light is used to toggle photoswitches back and forth between their two isomers even though the chromophores do not significantly absorb this type of light. The reactions are achieved through a "remote control" process by using photon upconverting hexagonal NaYF(4) nanocrystals doped with lanthanide ions. These nanoparticles absorb 980 nm light and convert it to wavelengths that can be used to trigger the photoswitches offering a practical means to potentially achieve 3D-data storage, drug-delivery, and photolithography.

1,3-Bis(2,4,6-trimethylphenyl)imidazolium chloride is reduced electrochemically and chemically to produce a nucleophilic carbene, namely 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene. The carbene was also shown to be compatible with and persistent in the ionic liquid tetradecyl(trihexyl)phosphonium chloride.

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.

Physical inclusion of small molecules in larger structural lattices is well known in the crystalline state and is a common feature of the chemistry of zeolites. In the liquid state, a variety of synthetic macrocyclic molecules are available to complex and contain smaller guest species. An alternative strategy for binding is explored: assembly of cavity-forming structures from small subunits. Encapsulation of small guest molecules such as methane can be achieved with a synthetic structure that assembles reversibly through hydrogen bonding.