pH-Responsive polymers

Nanotechnology has begun to play a remarkable role in various fields of science and technology. In biomedical applications, nanoparticles have opened new horizons, especially for biosensing, targeted delivery of therapeutics, and so forth. Among drug delivery systems (DDSs), smart nanocarriers that respond to specific stimuli in their environment represent a growing field. Nanoplatforms that can be activated by an external application of light can be used for a wide variety of photoactivated therapies, especially light-triggered DDSs, relying on photoisomerization, photo-cross-linking/un-cross-linking, photoreduction, and so forth. In addition, light activation has potential in photodynamic therapy, photothermal therapy, radiotherapy, protected delivery of bioactive moieties, anticancer drug delivery systems, and theranostics (i.e., real-time monitoring and tracking combined with a therapeutic action to different diseases sites and organs). Combinations of these approaches can lead to enhanced and synergi...

Smart Nanostructures for Cargo Delivery: Uncaging and Activating by Light

Smart drug delivery systems (DDSs) have attracted the attention of many scientists, as carriers that can be stimulated by changes in environmental parameters such as temperature, pH, light, electromagnetic fields, mechanical forces, etc. These smart nanocarriers can release their cargo on demand when their target is reached and the stimulus is applied. Using the techniques of nanotechnology, these nanocarriers can be tailored to be target-specific, and exhibit delayed or controlled release of drugs. Temperature-responsive nanocarriers are one of most important groups of smart nanoparticles (NPs) that have been investigated during the past decades. Temperature can either act as an external stimulus when heat is applied from the outside, or can be internal when pathological lesions have a naturally elevated termperature. A low critical solution temperature (LCST) is a special feature of some polymeric materials, and most of the temperature-responsive nanocarriers have been designed based on this feature. In...

Temperature-Responsive Smart Nanocarriers for Delivery Of Therapeutic Agents: Applications and Recent Advances

Biological signalling is regulated through a complex and tightly choreographed interplay between cells and their extracellular matrix. The spatiotemporal control of these interactions is essential for tissue function, and disruptions to this dialogue often result in aberrant cell fate and disease. When disturbances are well understood, correct biological function can be restored through the precise introduction of therapeutics. Moreover, model systems with modifiable physiochemical properties are needed to probe the effects of therapeutic molecules and to investigate cell–matrix interactions. Photoresponsive biomaterials benefit from spatiotemporal tunability, which allows for site-specific therapeutic delivery in vivo and 4D modulation of synthetic cell culture platforms to mimic the dynamic heterogeneity of the human body in vitro. In this Review, we discuss how light can be exploited to modify different biomaterials in the context of photomediated drug delivery and phototunable cell culture platforms. We survey various photochemistries for their applicability in vitro and in vivo and for the biochemical and biophysical modification of materials. Finally, we highlight emerging tools and provide an outlook for the field of photoresponsive biomaterials. Light can initiate chemistries with high spatial and temporal control. In this Review, photoresponsive biomaterials developed for controlled drug delivery and complex tissue engineering are investigated with a focus on photochemistries that provide dynamic precision.

Photoresponsive biomaterials for targeted drug delivery and 4D cell culture

Carbon-based nanomaterials include fullerenes, carbon nanotubes, graphene and its derivatives, graphene oxide, nanodiamonds, and carbon-based quantum dots. Due to their unique structural dimensions and excellent mechanical, electrical, thermal, optical and chemical properties, these materials have attracted significant interest in diverse areas, including biomedical applications. Among them, there has been recent focus on the imaging of cells and tissues and the delivery of therapeutic molecules for disease treatment and tissue repair. The broad-range one-photon property of carbon based-nanomaterials together with their biocompatibility and ease of functionalization has made them candidate imaging agents for tumor diagnosis. In particular, the intrinsic two-photon fluorescence property of carbon based-nanomaterials in the long wavelength region (near-infrared II) allows deep-tissue optical imaging. This review highlights the recent development on carbon based-nanomaterials in the field of one-photon and two-photon imaging and discusses their possible and promising diagnostic and therapeutic applications for the treatment of various diseases including cancer.

Carbon-based nanomaterials as an emerging platform for theranostics

Photo, pH, and thermo triple-responsive spiropyran-based copolymer nanoparticles for controlled release.

A photo, temperature, and pH responsive spiropyran-functionalized polymer: Synthesis, self-assembly and controlled release

Photo, pH and redox multi-responsive nanogels for drug delivery and fluorescence cell imaging

Here a near-infrared light and pH responsive nanocomposite comprising spiropyran-functionalized amphiphilic polymers and upconversion nanoparticles (UCNPs) is reported, which is prepared through the self-assembly of the amphiphilic polymers and the encapsulation of the UCNPs in the core of the self-assemblies. Upon near-infrared light irradiation, the upconversion fluorescence can induce the hydrophobic spiropyran to be isomerized to the hydrophilic merocyanine and disrupt the spherical morphology of the nanocomposites. Meanwhile, at low pH, the hydrophobic spiropyran can be also protonated to become hydrophilic merocyanine, and the self-assemblies are swollen. Model molecules, hydrophobic Coumarin 102, are demonstrated to be released from the nanocomposites triggered by the near-infrared light and acidic pH. In addition, the cytotoxicity of the nanocomposites loaded with anticancer drugs Doxorubicin on cancer cells indicates that the loaded drugs can be released and kill the cells effectively and the eff...

Nanocomposites of Spiropyran-Functionalized Polymers and Upconversion Nanoparticles for Controlled Release Stimulated by Near-Infrared Light and pH

Achieving high selectivity and conversion efficiency simultaneously is a challenge for visible‐light‐driven photocatalytic CO2 reduction into CH4. Here, a facile nanofiber synthesis method and a new defect control strategy at room‐temperature are reported for the fabrication of flexible mesoporous black Nb2O5 nanofiber catalysts that contain abundant oxygen‐vacancies and unsaturated Nb dual‐sites, which are efficient towards photocatalytic production of CH4. The oxygen‐vacancy decreases the bandgap width of Nb2O5 from 3.01–2.25 eV, which broadens the light‐absorption range from ultraviolet to visible‐light, and the dual sites in the mesopores can easily adsorb CO2, so that the intermediate product of CO* can be spontaneously changed into *CHO. The formation of a highly stable NbCHO* intermediate at the dual sites is proposed to be the key feature determining selectivity. The preliminary results show that without using sacrificial agents and photosensitizers, the nanofiber catalyst achieves 64.8% selectivity for CH4 production with a high evolution rate of 19.5 µmol g−1 h−1 under visible‐light. Furthermore, the flexible catalyst film can be directly used in devices, showing appealing and broadly commercial applications.

Shuo Chen

Papers

Photo, pH, and thermo triple-responsive spiropyran-based copolymer nanoparticles for controlled release.

A photo, temperature, and pH responsive spiropyran-functionalized polymer: Synthesis, self-assembly and controlled release

Photo, pH and redox multi-responsive nanogels for drug delivery and fluorescence cell imaging

Nanocomposites of Spiropyran-Functionalized Polymers and Upconversion Nanoparticles for Controlled Release Stimulated by Near-Infrared Light and pH

Fabrication of Flexible Mesoporous Black Nb2O5 Nanofiber Films for Visible‐Light‐Driven Photocatalytic CO2 Reduction into CH4