Reversibly Tuning the Viscosity of Peptide-Based Solutions Using Visible Light

Light can be used to design stimuli-responsive systems. We induce transient changes in the assembly of a low molecular weight gelator solution using a merocyanine photoacid. Through our approach, reversible viscosity changes can be achieved via irradiation, delivering systems where flow can be controlled non-invasively on demand.

Light-Triggered Self-Assembly of Peptide Nanoparticles into Nanofibers in Living Cells through Molecular Conformation Changes and H-Bond Interactions

Controlled self-assembly has attracted extensive interest in biological and nanotechnological applications. Enzymatic or biocatalytic triggered self-assembly is widely used for the diagnostic and prognostic marker in different pathologies because of their nanostructures and biological effects. However, it remains a great challenge to control the self-assembly of peptides in living cells with a high degree of spatial and temporal precision. Here we demonstrate a light-triggered platform that enables spatiotemporal control of self-assembly from nanoparticles into nanofibers in living cells through subtle molecular conformational changes and internal H-bonding interactions. The platform contained 3-methylene-2-(quinolin-8-yl) isoindolin-1-one, which acts as the light-controlled unit to disrupt the hydrophilic/lipophilic balance through the change of molecular conformation, and a peptide that can be a faster recombinant to assemble via H-bonding interactions. The process has good biocompatibility because it does not involve waste generation or oxygen consumption; moreover, the assembly rate constant was fast and up to 0.17 min^-1. It is applied to the regulation of molecular assembly in living cells. As such, our findings demonstrate that light-triggered controllable assembly can be applied for initiative regulating cellular behaviors in living systems.

Precise Controlled Target Molecule Release through Light-Triggered Charge Reversal Bridged Polysilsesquioxane Nanoparticles

Precise control of target molecule release time, site, and dosage remains a challenge in controlled release systems. We employed a photoresponsive molecule release system via light-triggered charge reversal nanoparticles to achieve a triggered, stepwise, and precise controlled release platform. This release system was based on photocleavage-bridged polysilsesquioxane nanoparticles which acted as nanocarriers of doxorubicin loaded on the surface via electrostatic interaction. The nanoparticles could reverse into positive charges triggered by 254 nm light irradiation due to the photocleavage of the o-nitrobenzyl bridged segment. The charge reversal property of the nanoparticles could release loaded molecules. Doxorubicin was selected as a positively charged model molecule. The as-prepared nanoparticles with an average size of 124 nm had an acceptable doxorubicin loading content up to 12.8%. The surface charge of the nanoparticles could rapidly reverse from negative (−28.20 mV) to positive (+18.9 mV) upon light irradiation for only 10 min. In vitro release experiments showed a cumulative release up to 96% with continuously enhancing irradiation intensity. By regulating irradiation parameters, precisely controlled drug release was carried out. The typical “stepped” profile could be accurately controlled in an on/off irradiation mode. This approach provides an ideal light-triggered molecule release system for location, timing, and dosage. This updated controlled release system, triggered by near-infrared or infrared light, will have greater potential applications in biomedical technology.

PNA-Based MicroRNA Detection Methodologies

MicroRNAs (miRNAs or miRs) are small noncoding RNAs involved in the fine regulation of post-transcriptional processes in the cell. The physiological levels of these short (20-22-mer) oligonucleotides are important for the homeostasis of the organism, and therefore dysregulation can lead to the onset of cancer and other pathologies. Their importance as biomarkers is constantly growing and, in this context, detection methods based on the hybridization to peptide nucleic acids (PNAs) are gaining their place in the spotlight. After a brief overview of their biogenesis, this review will discuss the significance of targeting miR, providing a wide range of PNA-based approaches to detect them at biologically significant concentrations, based on electrochemical, fluorescence and colorimetric assays.

Photodetachable Adhesion

Peeling from strong adhesion is hard, and sometimes painful. Herein, an approach is described to achieve both strong adhesion and easy detachment. The latter is triggered, on-demand, through an exposure to light of a certain frequency range. The principle of photodetachable adhesion is first demonstrated using two hydrogels as adherends. Each hydrogel has a covalent polymer network, but does not have functional groups for bonding, so that the two hydrogels by themselves adhere poorly. The two hydrogels, however, adhere strongly when an aqueous solution of polymer chains is spread on the surfaces of the hydrogels and is triggered to form a stitching polymer network in situ, in topological entanglement with the pre-existing polymer networks of the two hydrogels. The two hydrogels detach easily when the stitching polymer network is so functionalized that it undergoes a gel-sol transition in response to a UV light. For example, two pieces of alginate-polyacrylamide hydrogels achieve adhesion energies about 1400 and 10 J m^-2 , respectively, before and after the UV radiation. Experiments are conducted to study the physics and chemistry of this strong and photodetachable adhesion, and to adhere and detach various materials, including hydrogels, elastomers, and inorganic solids.

Biodegradable Polymer-Coated Multifunctional Graphene Quantum Dots for Light-Triggered Synergetic Therapy of Pancreatic Cancer

In this work, we reported the synthesis of an engineered novel nanocarrier composed of biodegradable charged polyester vectors (BCPVs) and graphene quantum dots (GQDs) for pancreatic cancer (MiaPaCa-2 cells) therapy applications. Such a nanocarrier was utilized to co-load doxorubicin (DOX) and small interfering ribonucleic acid (siRNA), resulting in the formation of GQD/DOX/BCPV/siRNA nanocomplexes. The resulting nanocomplexes have demonstrated high stability in physiologically mimicking media, excellent K-ras downregulation activity, and effective bioactivity inhibition for MiaPaCa-2 cells. More importantly, laser light was used to generate heat for the nanocomplexes via the photothermal effect to damage the cells, which was further employed to trigger the release of payloads from the nanocomplexes. Such triggered release function greatly enhanced the anticancer activity of the nanocomplexes. Preliminary colony formation study also suggested that GQD/DOX/BCPV/siRNA nanocomplexes are qualified carrier candidates in subsequent in vivo tests.

Light-Triggered Drug Release from 3D-Printed Magnetic Chitosan Microswimmers

Advances in design and fabrication of functional micro/nanomaterials have sparked growing interest in creating new mobile microswimmers for various healthcare applications, including local drug and other cargo ( e. g., gene, stem cell, and imaging agent) delivery. Such microswimmer-based cargo delivery is typically passive by diffusion of the cargo material from the swimmer body; however, controlled active release of the cargo material is essential for on-demand, precise, and effective delivery. Here, we propose a magnetically powered, double-helical microswimmer of 6 μm diameter and 20 μm length that can on-demand actively release a chemotherapeutic drug, doxorubicin, using an external light stimulus. We fabricate the microswimmers by two-photon-based 3D printing of a natural polymer derivative of chitosan in the form of a magnetic polymer nanocomposite. Amino groups presented on the microswimmers are modified with doxorubicin by means of a photocleavable linker. Chitosan imparts the microswimmers with biocompatibility and biodegradability for use in a biological setting. Controlled steerability of the microswimmers is shown under a 10 mT rotating magnetic field. With light induction at 365 nm wavelength and 3.4 × 10^-1 W/cm² intensity, 60% of doxorubicin is released from the microswimmers within 5 min. Drug release is ceased by controlled patterns of light induction, so as to adjust the desired release doses in the temporal domain. Under physiologically relevant conditions, substantial degradation of the microswimmers is shown in 204 h to nontoxic degradation products. This study presents the combination of light-triggered drug delivery with magnetically powered microswimmer mobility. This approach could be extended to similar systems where multiple control schemes are needed for on-demand medical tasks with high precision and efficiency.

Light-Triggered CO2 Breathing Foam via Nonsurfactant High Internal Phase Emulsion

Solid materials for CO₂ capture and storage have attracted enormous attention for gaseous separation, environmental protection, and climate governance. However, their preparation and recovery meet the problems of high energy and financial cost. Herein, a controllable CO₂ capture and storage process is accomplished in an emulsion-templated polymer foam, in which CO₂ is breathed-in under dark and breathed-out under light illumination. Such a process is likely to become a relay of natural CO₂ capture by plants that on the contrary breathe out CO₂ at night. Recyclable CO₂ capture at room temperature and release under light irradiation guarantee its convenient and cost-effective regeneration in industry. Furthermore, CO₂ mixed with CH₄ is successfully separated through this reversible breathing in and out system, which offers great promise for CO₂ enrichment and practical methane purification.

Multifunctional Liposomes for Image-Guided Intratumoral Chemo-Phototherapy

Intratumoral (IT) drug injections reduce systemic toxicity, but delivered volumes and distribution can be inconsistent. To improve IT delivery paradigms, porphyrin-phospholipid (PoP) liposomes are passively loaded with three hydrophilic cargos: sulforhodamine B, a fluorophore; gadolinium-gadopentetic acid, a magnetic resonance (MR) agent; and oxaliplatin, a colorectal cancer chemotherapeutic. Liposome composition is optimized so that cargo is retained in serum and storage, but is released in less than 1 min with exposure to near infrared light. Light-triggered release occurs with PoP-induced photooxidation of unsaturated lipids and all cargos release concurrently. In subcutaneous murine colorectal tumors, drainage of released cargo is delayed when laser treatment occurs 24 h after IT injection, at doses orders of magnitude lower than systemic ones. Delayed light-triggering results in substantial tumor shrinkage relative to controls a week following treatment, although regrowth occurs subsequently. MR imaging reveals that over this time frame, pools of liposomes within the tumor migrate to adjacent regions, possibly leading to altered spatial distribution during triggered drug release. Although further characterization of cargo loading and release is required, this proof-of-principle study suggests that multimodal theranostic IT delivery approaches hold potential to both guide injections and interpret outcomes, in particular when combined with chemo-phototherapy.

Metal Chelation Modulates Phototherapeutic Properties of Mitoxantrone-Loaded Porphyrin-Phospholipid Liposomes

Liposomes incorporating porphyrin-phospholipid (PoP) can be formulated to release entrapped contents in response to near-infrared (NIR) laser irradiation. Here, we examine effects of chelating copper or zinc into the PoP. Cu(II) and Zn(II) PoP liposomes, containing 10 molar % HPPH-lipid, exhibited unique photophysical properties and released entrapped cargo in response to NIR light. Cu-PoP liposomes exhibited minimal fluorescence and reduced production of reactive oxygen species upon irradiation. Zn-PoP liposomes retained fluorescence and singlet oxygen generation properties; however, they rapidly self-bleached under laser irradiation. Compared to the free base form, both Cu- and Zn-PoP liposomes exhibited reduced phototoxicity in mice. When loaded with mitoxantrone and administered intravenously at 5 mg/kg to mice bearing human pancreatic cancer xenografts, synergistic effects between the drug and the light treatment (for this particular dose and formulation) were realized with metallo-PoP liposomes. The drug-light-interval affected chemophototherapy efficacy and safety.

Lutecium fluoride hollow mesoporous spheres with enhanced up-conversion luminescent bioimaging and light-triggered drug release by gold nanocrystals

Uniform Na5Lu9F32 hollow mesoporous spheres (HMSs) have been successfully prepared by a facile and mild (50 °C for 5 h) coprecipitation process, and Au nanocrystals (NCs) with particle size of about 10 nm were conjugated to poly(ether imide) (PEI) modified HMSs by electrostatic interaction. Compared with Na5Lu9F32:Yb/Er HMSs, the up-conversion (UC) luminescence intensity of Na5Lu9F32:Yb/Er@Au HMSs was much higher under low pump power due to the local field enhancement (LFE) of Au NCs, and there is a surface plasmon resonance (SPR) effect with nonradiative transitions which generates a thermal effect. These two effects have been proved by theoretical discrete-dipole approximation (DDA) simulation. The good biocompatibility of Na5Lu9F32:Yb/Er@Au HMSs indicates them as a promising candidate in the biological field. Particularly, under near-infrared (NIR) laser irradiation, a rapid doxorubicin (DOX) release was achieved due to the thermal effect of Au NCs. In this case, Na5Lu9F32:Yb/Er@Au HMSs exhibit an apparent NIR light-controlled "on/off" drug release pattern. In addition, UC luminescent images uptaken by cells show brighter green and red emission under NIR laser excitation. Therefore, this novel multifunctional (mesoporous, enhanced UC luminescent, and light-triggered drug release) material should be potential as a suitable targeted cancer therapy carrier and bioimaging.