Dual Stimuli-Responsive Nucleobase-Functionalized Polymeric Systems as Efficient Tools for Manipulating Micellar Self-Assembly Behavior

Hydrogen-Bonding Interactions from Nucleobase-Decorated Supramolecular Polymer: Synthesis, Self-Assembly and Biomedical Applications

The fabrication of supramolecular materials for biomedical applications such as drug delivery, bioimaging, wound-dressing, adhesion materials, photodynamic/photothermal therapy, infection control (as antibacterial), etc. has grown tremendously, due to their unique properties, especially the formation of hydrogen bonding. Nevertheless, void space in the integration process, lack of feasibility in the construction of supramolecular materials of natural origin in living biological systems, potential toxicity, the need for complex synthesis protocols, and costly production process limits the actual application of nanomaterials for advanced biomedical applications. On the other hand, hydrogen bonding from nucleobases is one of the strategies that shed light on the blurred deployment of nanomaterials in medical applications, given the increasing reports of supramolecular polymers that promote advanced technologies. Herein, we review the extensive body of literature about supramolecular functional biomaterials based on nucleobase hydrogen bonding pertinent to different biomedical applications. It focuses on the fundamental understanding about the synthesis, nucleobase-decorated supramolecular architecture, and novel properties with special emphasis on the recent developments in the assembly of nanostructures via hydrogen-bonding interactions of nucleobase. Moreover, the challenges, plausible solutions, and prospects of the so-called hydrogen bonding interaction from nucleobase for the fabrication of functional biomaterials are outlined.

Photoreactive Mercury-Containing Metallosupramolecular Nanoparticles with Tailorable Properties That Promote Enhanced Cellular Uptake for Effective Cancer Chemotherapy

A new potential route to enhance the efficiency of supramolecular polymers for cancer chemotherapy was successfully demonstrated by employing a photosensitive metallosupramolecular polymer (Hg-BU-PPG) containing an oligomeric poly(propylene glycol) backbone and highly sensitive pH-responsive uracil-mercury-uracil (U-Hg-U) bridges. This route holds great promise as a multifunctional bioactive nano-object for development of more efficient and safer cancer chemotherapy. Owing to the formation of uracil photodimers induced by ultraviolet irradiation, Hg-BU-PPG can form a photo-cross-linked structure and spontaneously forms spherical nanoparticles in aqueous solution. The irradiated nanoparticles possess many unique characteristics, such as unique fluorescence behavior, highly sensitive pH-responsiveness, and intriguing phase transition behavior in aqueous solution as well as high structural stability and antihemolytic activity in biological media. More importantly, a series of cellular studies clearly confirmed that the U-Hg-U photo-cross-links in the irradiated nanoparticles substantially enhance their selective cellular uptake by cancer cells via macropinocytosis and the mercury-loaded nanoparticles subsequently induce higher levels of cytotoxicity in cancer cells (compared to non-irradiated nanoparticles), without harming normal cells. These results are mainly attributed to cancer cell microenvironment-triggered release of mercury ions from disassembled nanoparticles, which rapidly induce massive levels of apoptosis in cancer cells. Overall, the pH-sensitive U-Hg-U photo-cross-links within this newly discovered supramolecular system are an indispensable factor that offers a potential path to remarkably enhance the selective therapeutic effects of functional nanoparticles toward cancer cells.

Nanomaterials based on thermosensitive polymer in biomedical field

The progress of nanotechnology enables us to make use of the special properties of materials on the nanoscale and open up many new fields of biomedical research. Among them, thermosensitive nanomaterials stand out in many biomedical fields because of their “intelligent” behavior in response to temperature changes. However, this article mainly reviews the research progress of thermosensitive nanomaterials, which are popular in biomedical applications in recent years. Here, we simply classify the thermally responsive nanomaterials according to the types of polymers, focusing on the mechanisms of action and their advantages and potential. Finally, we deeply investigate the applications of thermosensitive nanomaterials in drug delivery, tissue engineering, sensing analysis, cell culture, 3D printing, and other fields and probe the current challenges and future development prospects of thermosensitive nanomaterials.

Thermosensitive core-rigid micelles of monomethoxy poly(ethylene glycol)-deoxy cholic acid

Background

Thermosensitive micelles with rigid cores that exhibit a reversible lower critical solution temperature at 30–35 °C can be applied for drug delivery.

Method

Hydrophilic monomethoxy poly(ethylene glycol) was conjugated to hydrophobic deoxycholic acid to prepare monomethoxy poly(ethylene glycol)-deoxycholic acid (mPEG-DC). Micelle formation and thermosensitive solution behavior were studied using various methods, including hydrophobic dye solubilization, transmission electron microscopy, dynamic light scattering, turbidity measurement, microcalorimetry, and ¹H-NMR spectroscopy. Drug release from the thermosensitive micelles was demonstrated using estradiol, a model drug.

Results

The mPEG-DC formed micelles with a critical micelle concentration of 0.05 wt.% and an average size of 15 nm. Aqueous mPEG-DC solutions exhibit a lower critical solution temperature (LCST) that is independent of concentration and reversible over heating and cooling cycles. The LCST transition is an entropically driven process involving dehydration of the PEG shell. The thermosensitive mPEG-DC micelles with rigid DC cores were applied as an estradiol delivery system in which estradiol was released, without initial burst, over the 16 days in a diffusion-controlled manner.

Conclusions

This study suggests that mPEG-DCs form thermosensitive micelles with rigid cores that can function as an excellent diffusion-controlled hydrophobic drug delivery system without initial burst release.

Graphical Abstract

Thermosensitive core-rigid micelles of monomethoxy poly(ethylene glycol)-deoxy cholic acid

Supplementary Information

The online version contains supplementary material available at 10.1186/s40824-022-00263-9.

Single and Multiple Stimuli-Responsive Polymer Particles for Controlled Drug Delivery

Polymers that can change their properties in response to an external or internal stimulus have become an interesting platform for drug delivery systems. Polymeric nanoparticles can be used to decrease the toxicity of drugs, improve the circulation of hydrophobic drugs, and increase a drug’s efficacy. Furthermore, polymers that are sensitive to specific stimuli can be used to achieve controlled release of drugs into specific areas of the body. This review discusses the different stimuli that can be used for controlled drug delivery based on internal and external stimuli. Internal stimuli have been defined as events that evoke changes in different characteristics, inside the body, such as changes in pH, redox potential, and temperature. External stimuli have been defined as the use of an external source such as light and ultrasound to implement such changes. Special attention has been paid to the particular chemical structures that need to be incorporated into polymers to achieve the desired stimuli response. A current trend in this field is the incorporation of several stimuli in a single polymer to achieve higher specificity. Therefore, to access the most recent advances in stimuli-responsive polymers, the focus of this review is to combine several stimuli. The combination of different stimuli is discussed along with the chemical structures that can produce it.

Nucleobase-containing polymer architectures controlled by supramolecular interactions: the key to achieve biomimetic platforms with various morphologies

Challenges and opportunities in supramolecular self-assembly of synthetic nucleobase-containing copolymers.

Photoreactive Cytosine-Functionalized Self-Assembled Micelles with Enhanced Cellular Uptake Capability for Efficient Cancer Chemotherapy

Design, fabrication, and control of photoreactive supramolecular macromers─which are composed of a thermoresponsive polymer backbone and photoreactive nucleobase end-groups─to achieve the desired physical-chemical performance and provide the high efficiency required for chemotherapy drug delivery purposes still present challenges. Herein, a difunctional cytosine-terminated supramolecular macromer was successfully obtained at high yield. UV-irradiation induces the formation of cytosine photodimers within the structure. The irradiated macromer can self-assemble into nanosized spherical micelles in water that possess a number of interesting and unique features, such as desired micellar size and morphology, tunable drug-loading capacity, and excellent structural stability in serum-containing medium, in addition to well-controlled drug-release behaviors in response to changes in environmental temperature and pH; these extremely desirable, rare features are required to augment the functions of polymeric nanocarriers for drug delivery. Importantly, a series of in vitro studies demonstrated that photodimerized cytosine moieties within the drug-loaded micelles substantially enhance their internalization and accumulation inside cells via endocytosis and subsequently lead to induction of massive apoptotic cell death compared with the corresponding nonirradiated micelles. Thus, this newly developed "photomodified" nanocarrier system could provide a potentially fruitful route to enhance the drug delivery performance of nanocages without the need to introduce targeting moieties or additional components.

Mercury-containing supramolecular micelles with highly sensitive pH-responsiveness for selective cancer therapy

Construction and manipulation of metal-based supramolecular polymers-which are based on a combination of nucleobase hydrogen bonding interactions and functional metal ions-to obtain the desired physicochemical properties and achieve the efficacy and safety required for biomedical applications remain extremely challenging. We successfully designed and synthesized a new mercury-based supramolecular polymer, Hg-BU-PPG, containing an oligomeric polypropylene glycol backbone and pH-sensitive uracil-mercury-uracil (U-Hg-U) linkages. This multifunctional metallo-supramolecular material spontaneously self-organizes into nanosized spherical micelles in aqueous solution. The micelles possess several attractive properties, including desired long-term structural stability in serum-rich conditions, unique fluorescence behavior and highly sensitive, well-controlled pH-responsiveness. Interestingly, Hg-BU-PPG micelles exhibited strong, selective cytotoxic effects towards cancer cells in vitro, without harming normal cells. The highly selective cytotoxicity can be attributed to rapid dissociation of the U-Hg-U complexes within the micelles in the mildly acidic intracellular pH of cancer cells, followed by release of inherently toxic mercury ions. Importantly, fluorescence microscopy and flow cytometry clearly demonstrated that Hg-BU-PPG selectively entered the cancer cells via endocytosis and rapidly promoted massive apoptotic cell death. In contrast, internalization of Hg-BU-PPG by normal cells was limited, resulting in high biocompatibility and no cytotoxic effects. Thus, this newly discovered 'cytotoxicity-concealing' supramolecular system could represent a viable route to enhance the safety and efficacy of cancer therapy and bioimaging via a strategy that does not require incorporation of anticancer drugs and fluorescent probes. STATEMENT OF SIGNIFICANCE: We report a significant breakthrough in the construction of mercury-containing supramolecular polymers, namely the creation of multifunctional micelles with unique chemical and physical properties conferred by pH-sensitive uracil-mercury-uracil (U-Hg-U) linkages and tunable structural and dynamical features due to the presence of hydrogen-bonded uracil moieties. Importantly, in vitro experiments clearly demonstrated that introduction of the U-Hg-U complexes into the micelles not only improved the efficiency of selective uptake via endocytosis into cancer cells, but also accelerated the induction of massive apoptotic cell death. Thus, this work provides crucial new insight for the development of metallo-supramolecular polymeric micelles that may substantially enhance the safety and efficacy of cancer therapy and bioimaging without requiring incorporation of anticancer drugs or fluorescent probes.

Utilizing Stimuli Responsive Linkages to Engineer and Enhance Polymer Nanoparticle-Based Drug Delivery Platforms

The devastating nature of cancer continues to be one of the leading causes of death in the world. Chemotherapy is among the most common forms of cancer treatment but comes with a host of adverse effects caused by the therapeutic agents damaging healthy tissue and organs. To limit these side effects, scientists have been designing stimuli responsive drug delivery vessels for targeted release. This Review focuses on the incorporation of stimuli responsive linkages in targeted drug delivery systems to enhance therapeutic efficiency. These platforms are primarily employed to control the distribution of anticancer agents in the body to reduce the adverse side effects caused by their toxicities. We will outline how drug delivery vessels are constructed so that exposure to select environmental and external stimuli releases the enclosed drug only at the target site. Stimuli responsive components are integrated within drug delivery vessels in the form of cross-linkers, polymers, and surface modifications. The changes, these moieties undergo upon stimuli exposure, cascade into larger scale alterations to the platforms, resulting in complete disassembly, reversible morphological variations, and enhanced cellular uptake. The ability for these modes of delivery to be initiated exclusively under stimuli exposure allows for release of toxic therapeutic agents to be confined only to the affected area.

Photo-Responsive Supramolecular Micelles for Controlled Drug Release and Improved Chemotherapy

Development of stimuli-responsive supramolecular micelles that enable high levels of well-controlled drug release in cancer cells remains a grand challenge. Here, we encapsulated the antitumor drug doxorubicin (DOX) and pro-photosensitizer 5-aminolevulinic acid (5-ALA) within adenine-functionalized supramolecular micelles (A-PPG), in order to achieve effective drug delivery combined with photo-chemotherapy. The resulting DOX/5-ALA-loaded micelles exhibited excellent light and pH-responsive behavior in aqueous solution and high drug-entrapment stability in serum-rich media. A short duration (1-2 min) of laser irradiation with visible light induced the dissociation of the DOX/5-ALA complexes within the micelles, which disrupted micellular stability and resulted in rapid, immediate release of the physically entrapped drug from the micelles. In addition, in vitro assays of cellular reactive oxygen species generation and cellular internalization confirmed the drug-loaded micelles exhibited significantly enhanced cellular uptake after visible light irradiation, and that the light-triggered disassembly of micellar structures rapidly increased the production of reactive oxygen species within the cells. Importantly, flow cytometric analysis demonstrated that laser irradiation of cancer cells incubated with DOX/5-ALA-loaded A-PPG micelles effectively induced apoptotic cell death via endocytosis. Thus, this newly developed supramolecular system may offer a potential route towards improving the efficacy of synergistic chemotherapeutic approaches for cancer.

Adenine-Functionalized Supramolecular Micelles for Selective Cancer Chemotherapy

Functional supramolecular micelles containing self-complementary multiple hydrogen bonding adenine groups (A-PPG) can spontaneously self-assemble into stable nanosized micelles in aqueous solution. These micelles can be used to selectively deliver anticancer drugs to cancer cells and effectively promote tumor cell death via apoptosis, without harming normal cells. The drug-loaded micelles exhibit tunable drug-loading capacity and rapid pH-triggered drug release under acidic conditions, as well as a high drug-entrapment stability in serum-rich media due to the reversible hydrogen-bonded adenine-adenine interactions within the micellar interior; these properties are critical to achieving effective chemotherapeutic drug delivery and controlled drug release. In vitro assays show that the drug-loaded micelles exert significant cytotoxic effects on cancer cells, with minimal effects on normal cells under physiological conditions. Cytotoxicity assays using A-PPG micelles loaded with different anticancer drugs confirm these effects. Importantly, cellular internalization and flow cytometric analyses demonstrate that the adenine moieties within A-PPG micelles significantly increase selective endocytic uptake of the supramolecular micelles by cancer cells, which in turn induce apoptotic cell death and substantially enhance the response to chemotherapy. Thus, A-PPG micelles can improve the safety and efficacy of cancer chemotherapy.

Photosensitive Supramolecular Micelle-Mediated Cellular Uptake of Anticancer Drugs Enhances the Efficiency of Chemotherapy

The development of stimuli-responsive supramolecular micelles with high drug-loading contents that specifically induce significant levels of apoptosis in cancer cells remains challenging. Herein, we report photosensitive uracil-functionalized supramolecular micelles that spontaneously form via self-assembly in aqueous solution, exhibit sensitive photo-responsive behavior, and effectively encapsulate anticancer drugs at high drug-loading contents. Cellular uptake analysis and double-staining flow cytometric assays confirmed the presence of photo-dimerized uracil groups within the irradiated micelles remarkably enhanced endocytic uptake of the micelles by cancer cells and subsequently led to higher levels of apoptotic cell death, and thus improved the therapeutic effect in vitro. Thus, photo-dimerized uracil-functionalized supramolecular micelles may potentially represent an intelligent nanovehicle to improve the safety, efficacy, and applicability of cancer chemotherapy, and could also enable the development of nucleobase-based supramolecular micelles for multifunctional biomaterials and novel biomedical applications.

Tailor-made legumain/pH dual-responsive doxorubicin prodrug-embedded nanoparticles for efficient anticancer drug delivery and in situ monitoring of drug release

Legumain enzyme is a well-conserved lysosomal cysteine protease and is over-expressed in many tumor cells and tumor stromal cells and exhibits higher protease activity under acidic conditions, such as in lysosomes and endosomes. Legumain enzyme-triggered drug delivery systems have demonstrated potential therapeutic values in cancer targeted therapy. To realize a more efficient delivery of anticancer therapeutic agents, we herein report a legumain/pH dual-responsive drug delivery system for enhancing site-specific controlled release of antitumor drugs. The carrier (named "DS-NA") is a hybrid vector constituting PEG-b-PBLA polymers, pH-responsive OAPI polymers, and legumain-sensitive peptide-doxorubicin prodrug decorated fluorescent carbon dots (CDs-C9-AANL-DOX). In tumor cells, DS-NA could disassemble rapidly in acidic environments, and then release doxorubicin through legumain digestion. Except as a drug vector, the drug release process from DS-NA could also be dynamically monitored by CLSM as the DOX was released from the surface of CDs through the AANL peptide linker digested by legumain, then transferred into the cell nucleus and exerted cytotoxicity, while the CDs themselves remained in the cytoplasm. As a control, the CDs-C9-DOX, which did not contain the AANL peptide linker, also still resided in the cytoplasm. Furthermore, in vivo studies show that DS-NA had a stronger inhibitory effect on tumor tissue with attenuated side effects to normal tissues than control nanoparticles or free drugs, which may be due to comprehensive effects including pH/legumain dual-triggered drug release, long blood circulation periods, and EPR effects. Together, a combination strategy of acid sensitivity and legumain enzyme sensitivity used for site-specific controlled release of drugs provides a novel method for enhanced and precise antitumor chemotherapy.

Multifunctional adenine-functionalized supramolecular micelles for highly selective and effective cancer chemotherapy

Adenine-functionalized supramolecular micelles are rapidly endocytosed by cancer cells and enable selective induction of tumor cell death, without harming normal cells.

Hydrogen-bonded supramolecular micelle-mediated drug delivery enhances the efficacy and safety of cancer chemotherapy

Multiple hydrogen-bonded supramolecular polymers tend to form stable spherical micelles with oppositely charged anticancer drugs in biological environments, which improves cellular drug uptake and more effectively induces apoptosis in cancer cells.

Supramolecular nucleobase-functionalized polymers: synthesis and potential biological applications

This Perspective article summarizes the synthesis of nucleobase functionalized polymers and highlights issues and challenges following their potential biological applications.

Adenine-functionalized polypropylene glycol: A novel stationary phase for gas chromatography offering good inertness for acids and bases combined with a unique selectivity

This work presents the investigation of utilizing adenine-functionalized polypropylene glycol (APPG) for capillary gas chromatographic separations. The statically coated APPG column (0.25 mm i.d.) showed moderate polarity and high column efficiencies of 4660 plates/m and 4376 plates/m determined by n-octanol and naphthalene, respectively. Remarkably, the APPG column baseline resolved all the components of the Grob test mixture and displayed good peak shapes for some stringent analytes that are prone to peak tailing or severe adsorption. Also, it achieved complete separation of dimethylaniline isomers, which are difficult to be resolved due to their high resemblance in structures and properties. The above results demonstrate the high selectivity and inertness of the APPG column and its distinct advantages over the polypropylene glycol (PPG) column and commercial polyethylene glycol (PEG) column. In addition, its separation performance has good repeatability with the RSD values on retention times below 0.05% for run-to-run, 0.11-0.12% for day-to-day and 1.7-1.9% for column-to-column, respectively. Further, the APPG column was applied to determination of isomer impurities in commercial dimethylaniline products and to determination of the additives of anilines and phenols in a hair-dye product, proving its great potential for practical GC analysis.

Entrapment of an adenine derivative by a photo-irradiated uracil-functionalized micelle confers controlled self-assembly behavior

HYPOTHESIS

Invoking cooperative assembly of the uracil-functionalized supramolecular polymer BU-PPG [uracil end-capped poly(propylene glycol)] upon association with the nucleobase adenine derivative A-MA [methyl 3-(6-amino-9H-purin-9-yl)propanoate] as a model drug provides a new concept to control and tune the properties of supramolecular complexes and holds significant potential for the development of safer, more effective drug delivery systems.

EXPERIMENTS

BU-PPG and A-MA were successfully developed and exhibited specific recognition and high affinity, which enabled reversible complementary adenine-uracil (A-U) hydrogen bonding-induced formation of spherical micelles in aqueous solution. The self-assembly and controllable A-MA release behavior of BU-PPG/A-MA micelles were studied using morphological analysis and optical and light scattering techniques to investigate the effect of photoirradiation and temperature on the complementary hydrogen bond interactions between BU-PPG and A-MA.

FINDINGS

The resulting micelles possess unusual physical properties, including controlled photoreactivity kinetics, controllable self-assembled morphology and low cytotoxicity in vitro, as well as reversible temperature-responsive behavior. Importantly, irradiated micelles exhibited excellent long-term structural stability under normal physiological conditions and serum disturbance. Increasing the temperature triggered rapid release of A-MA by disrupting A-U complexes. These findings represent an entirely new, promising strategy for the development of multi-controlled release drug delivery nanocarriers based on complementary hydrogen bonding interactions.

Dual stimuli-responsive supramolecular boron nitride with tunable physical properties for controlled drug delivery

The new concept of modifying and tailoring the properties of existing two-dimensional (2D) nanomaterials by invoking the assembly of supramolecular networks upon association with a adenine-functionalized macromer (A-PPG) has significant potential to facilitate the development of highly water-dispersible few-layered 2D nanosheets. In this study, we propose that water-soluble A-PPG directly self-assembles into a long-period stacking-ordered lamellar structure over the surface of hexagonal boron nitride (BN) in aqueous solution, due to the efficient non-covalent interactions between A-PPG and BN nanosheets. The layer number of BN nanosheets can be easily tuned by altering the mass ratio of the A-PPG and BN blend, and the resulting exfoliated nanosheets also exhibit excellent temperature/pH-responsive behavior, biocompatibility and extremely high drug-loading capacity (up to 36.2%), features that are highly desirable yet exceedingly rare in traditional 2D nanomaterials. Importantly, in vitro drug release studies showed the drug-loaded nanosheets function as a stable nanocarrier with excellent stability and drug entrapment under normal physiological conditions. Increasing the environmental temperature to 40 °C or decreasing the pH to 5.5 triggered rapid release of the encapsulated drug from the drug-loaded nanosheets, suggesting this newly developed material has potential as a novel multi-responsive 2D nanocarrier to safely deliver drugs and effectively facilitate controlled drug release under specific microenvironmental conditions. This study provides new insight towards the promising application of this system in controlled release drug delivery systems.

The light-controlling of temperature-responsivity in stimuli-responsive polymers

Light-controlling of phase separation in temperature-responsive polymer solutions by using light-responsive materials for reversible controlling physical and chemical properties of the media with an out-of-system stimulus with tunable intensity.

Impact of Glycolipid Hydrophobic Chain Length and Headgroup Size on Self-Assembly and Hydrophobic Guest Release

Encapsulation of a hydrophobic guest molecule inside a micelle and its stimuli-sensitive release is a useful strategy for target-specific drug delivery. Herein, nine biobased glycolipids were derived from plant sources. The influence of headgroup on the stability and aggregation pattern in water with different alkyl chain lengths was investigated to deduce the structure-property relationship. External factors, such as temperature, pH, and NaCl and urea concentrations, were employed to explore stimuli response of glycolipid nanoassemblies. Furthermore, solvatochromic dyes, such as pyrene, N-phenyl-1-naphthylamine, and curcumin, were utilized to examine hydrophobe loading capacities of these glycolipid assemblies. A fluorescence study was performed to investigate the enzyme-sensitive hydrophobe release. Interestingly, the pH-sensitive hydrophobic guests showed pH-responsive release from dynamic micelles. Finally, the synthesized glycolipids revealed their nanoassemblies as smart carriers for hydrophobic cargo.

Dynamic tungsten diselenide nanomaterials: supramolecular assembly-induced structural transition over exfoliated two-dimensional nanosheets

Supramolecular polymers can easily control the lamellar microstructures on exfoliated tungsten diselenide nanosheets.

A simple and effective method for direct exfoliation of tungsten diselenide (WSe₂) into few-layered nanosheets has been successfully developed by employing a low molecular weight adenine-functionalized supramolecular polymer (A-PPG). In this study, we discover A-PPG can self-assemble into a long-range, ordered lamellar microstructure on the surface of WSe₂ due to the efficient non-covalent interactions between A-PPG and WSe₂. Morphological and light scattering studies confirmed the dynamic self-assembly behavior of A-PPG has the capacity to efficiently manipulate the transition between contractile and extended lamellar microstructures on the surface of metallic 1T-phase and semiconducting 2H-phase WSe₂ nanosheets, respectively. The extent of WSe₂ exfoliation can be easily controlled by systematically adjusting the amount of A-PPG in the composites, to obtain nanocomposites with the desired functional characteristics. In addition, the resulting composites possess unique liquid–solid phase transition behavior and excellent thermoreversible properties, revealing the self-assembled lamellar structure of A-PPG functions as a critical factor to manipulate and tailor the physical properties of exfoliated WSe₂. This newly developed method of producing exfoliated WSe₂ provides a useful conceptual and potential framework for developing WSe₂-based multifunctional nanocomposites to extend their application in solution-processed semiconductor devices.

Photoresponsive Drug/Gene Delivery Systems

Light as an external stimulus can be precisely manipulated in terms of irradiation time, site, wavelength, and density. As such, photoresponsive drug/gene delivery systems have been increasingly pursued and utilized for the spatiotemporal control of drug/gene delivery to enhance their therapeutic efficacy and safety. In this review, we summarized the recent research progress on photoresponsive drug/gene delivery, and two major categories of delivery systems were discussed. The first category is the direct responsive systems that experience photoreactions on the vehicle or drug themselves, and different materials as well as chemical structures responsive to UV, visible, and NIR light are summarized. The second category is the indirect responsive systems that require a light-generated mediator signal, such as heat, ROS, hypoxia, and gas molecules, to cascadingly trigger the structural transformation. The future outlook and challenges are also discussed at the end.

Tuning thermoresponsive network materials through macromolecular architecture and dynamic thiol-Michael chemistry

Synthesis of precision polymers crosslinked with dynamic thiol-Michael adducts is developed, and the materials are characterized to determine structure–property relationships.

A new difluoromethoxyl-containing acrylate monomer for PEG-b-PDFMOEA amphiphilic diblock copolymers

This article reports the first synthesis of a well-defined difluoromethoxyl-containing polyacrylate via ATRP.