New diagnostic and therapeutic strategies for myocardial infarction via nanomaterials

Myocardial infarction is lethal to patients because of insufficient blood perfusion to vital organs. Several attempts have been made to improve its prognosis, among which nanomaterial research offers an opportunity to address this problem at the molecular level and has the potential to improve disease prevention, diagnosis, and treatment significantly. Up to now, nanomaterial-based technology has played a crucial role in broad novel diagnostic and therapeutic strategies for cardiac repair. This review summarizes various nanomaterial applications in myocardial infarction from multiple aspects, including high precision detection, pro-angiogenesis, regulating immune homeostasis, and miRNA and stem cell delivery vehicles. We also propose promising research hotspots that have not been reported much yet, such as conjugating pro-angiogenetic elements with nanoparticles to construct drug carriers, developing nanodrugs targeting other immune cells except for macrophages in the infarcted myocardium or the remote region. Though most of those strategies are preclinical and lack clinical trials, there is tremendous potential for their further applications in the future.

Comprehensive studies of continuous flow reversible addition–fragmentation chain transfer copolymerization and its application for photoimaging materials

Thorough studies of RAFT copolymerization in a continuous flow to gain deeper insights into kinetics, reactivity, and applicability were conducted with monomers and solvents utilizable for chemically amplified resist systems.

The effects of cononsolvents on the synthesis of responsive particles via polymerisation-induced thermal self-assembly

Responsive nanogels were synthesised via RAFT-mediated polymerisation-induced thermal self-assembly in cononsolvent mixtures of water and ethanol. The solvent mixture affected the particle size, tacticity and thermal properties.

Gated thermoelectric sensation by nanochannels grafted with thermally responsive polymers

We report that conical PET nanochannels grafted with thermally responsive polymers can mimic the thermosensation of protein channels in living organisms, showing an adjustable gated potential rather than current response to an ambient temperature stimulus, which is more consistent with real biochannels.

Biodegradable Thermomagnetically Responsive Soft Untethered Grippers

Soft-robotic devices such as polymeric microgrippers offer the possibility for pick and place of fragile biological cargo in hard-to-reach conduits with potential applications in drug delivery, minimally invasive surgery, and biomedical engineering. Previously, millimeter-sized self-folding thermomagnetically responsive soft grippers have been designed, fabricated, and utilized for pick-and-place applications but there is a concern that such devices could get lost or left behind after their utilization in practical clinical applications in the human body. Consequently, strategies need to be developed to ensure that these soft-robotic devices are biodegradable so that they would disintegrate if left behind in the body. In this paper, we describe the photopatterning of bilayer gels composed of a thermally responsive high-swelling poly(oligoethylene glycol methyl ether methacrylate ( M_n = 500)-bis(2-methacryloyl)oxyethyl disulfide), P(OEGMA-DSDMA), and a low-swelling poly(acrylamide- N, N'-bis(acyloyl)cystamine) hydrogel, in the shape of untethered grippers. These grippers can change shape in response to thermal cues and open and close due to the temperature-induced swelling of the P(OEGMA-DSDMA) layer. We demonstrate that the grippers can be doped with magnetic nanoparticles so that they can be moved using magnetic fields or loaded with chemicals for potential applications as drug-eluting theragrippers. Importantly, they are also biodegradable at physiological body temperature (∼37 °C) on the basis of cleavage of disulfide bonds by reduction. This approach that combines thermoresponsive shape change, magnetic guidance, and biodegradability represents a significant advance to the safe implementation of untethered shape-changing biomedical devices and soft robots for medical and surgical applications.

Core-Shell Nanoparticles as an Efficient, Sustained, and Triggered Drug-Delivery System

One of the challenges in designing a successful drug-delivery vehicle is the control over drug release. Toward this, a number of multifunctional nanoparticles with multiple triggers and complex chemistries have been developed. To achieve an efficient and maximum therapeutic effect, a trigger dependent drug-delivery system with sustained release is desirable. In this paper, we report the use of a combination of thermoresponsive gold core and polymeric shell nanoparticles that can provide a sustained, triggered release of doxorubicin, making the system more efficient compared to individual nanoparticles. The selection of the system was dependent on the best trigger applicable in biological systems and a component responsive to that trigger. Because of the best tissue penetration depth observed for radiofrequency (rf), we chose rf as a trigger. Whereas the gold nanoparticles (AuNPs) provided hyperthermia trigger on exposure to rf fields, the thermoresponsiveness was endowed by poly(N-isopropylacrylamide) (pNIPAm)-based polymer shells. AuNPs with three different compositions of shells, only pNIPAm and p(NIPAm-co-NIPMAm) with the ratio of NIPAm/N-(isopropylmethacrylamide) (NIPMAm) 1:1 (pNIPMAm50) and 1:3 (pNIPMAm75), were synthesized. We observed that the polymer coating on the AuNPs did not affect the heating efficiency of AuNPs by rf and exhibited a temperature-dependent release of the chemotherapeutic drug, doxorubicin. The nanoparticles were biocompatible, stable in biologically relevant media, and were able to show a burst as well as a sustained release, which was rf-dependent. Interestingly, we observed that when HeLa cells were treated with doxorubicin-loaded gold core-polymeric shell NPs and exposed to rf for varying times, the mixture of the two polymeric shell nanoparticles induced more cell death as compared to the cells treated with single nanoparticles, suggesting that such multi-nanoparticle systems can be more efficacious delivery systems instead of a single multicomponent system.

Tunable Dual-Thermoresponsive Core-Shell Nanogels Exhibiting UCST and LCST Behavior

Thermoresponsive polymers change their physical properties as the temperature is changed and have found extensive use in a number of fields, especially in tissue engineering and in the development of drug delivery systems. The synthesis of a novel core-shell nanogel composed of N-isopropylacrylamide and sulfobetaine by reversible addition fragmentation chain transfer polymerization is reported. The core-shell architecture of the nanogels is confirmed using energy dispersive X-ray spectroscopy in scanning transmission electron microscopy. These nanogels exhibit dual thermoresponsive behavior, i.e., the core of the nanogel exhibits lower critical solution temperature, while the shell displays upper critical solution temperature behavior. Transition temperatures can be easily tuned by changing the molecular weight of the constituent polymer. These nanogels can be efficiently used in temperature-triggered delivery of therapeutic proteins and drugs.

Inhibition of protein aggregation by zwitterionic polymer-based core-shell nanogels

Protein aggregation is a process by which misfolded proteins polymerizes into aggregates and forms fibrous structures with a β-sheet conformation, known as amyloids. It is an undesired outcome, as it not only causes numerous neurodegenerative diseases, but is also a major deterrent in the development of protein biopharmaceuticals. Here, we report a rational design for the synthesis of novel zwitterionic polymer-based core-shell nanogels via controlled radical polymerization. Nanogels with different sizes and functionalities in the core and shell were prepared. The nanogels exhibit remarkable efficiency in the protection of lysozyme against aggregation. Addition of nanogels suppresses the formation of toxic fibrils and also enables lysozyme to retain its enzymatic activity. Increasing the molecular weight and degree of hydrophobicity markedly increases its overall efficiency. Investigation of higher order structures revealed that lysozyme when heated without any additive loses its secondary structure and transforms into a random coil conformation. In contrast, presence of nanogels facilitates the retention of higher order structures by acting as molecular chaperones, thereby reducing molecular collisions. The present study is the first to show that it is possible to design zwitterionic nanogels using appropriate polymerization techniques that will protect proteins under conditions of extreme stress and inhibit aggregation.

The effects of the photo-induced proton generation on the assembly formation of dual-temperature and pH responsive block copolymers

The effects caused by photo-induced proton generation on the assembly formation of dual-temperature/pH-responsive block copolymers are investigated.

From LCST to UCST: the phase separation behaviour of thermo-responsive polysiloxanes with the solubility parameters of solvents

Thermo-responsive polysiloxanes with tunable LCST- and UCST-type phase separation in mixed solvents were synthesised via a facile, highly efficient, catalyst-free aza-Michael addition of poly(aminopropylmethylsiloxane) to N-isopropylacrylamide.

Stimuli-responsive nanogel composites and their application in nanomedicine

Nanogels are nanosized crosslinked polymer networks capable of absorbing large quantities of water. Specifically, smart nanogels are interesting because of their ability to respond to biomedically relevant changes like pH, temperature, etc. In the last few decades, hybrid nanogels or composites have been developed to overcome the ever increasing demand for new materials in this field. In this context, a hybrid refers to nanogels combined with different polymers and/or with nanoparticles such as plasmonic, magnetic, and carbonaceous nanoparticles, among others. Research activities are focused nowadays on using multifunctional hybrid nanogels in nanomedicine, not only as drug carriers but also as imaging and theranostic agents. In this review, we will describe nanogels, particularly in the form of composites or hybrids applied in nanomedicine.

Stimuli-Responsive Cellulose Nanocrystals for Surfactant-Free Oil Harvesting

Cellulose nanocrystals with grafted binary polymer brushes (CNC-BPB), poly(oligoethylene glycol) methacrylate (POEGMA) and poly(methacrylic acid) (PMAA), were prepared by cerium-mediated polymerization in aqueous solution. The physical properties of CNC-BPB can be controlled by external triggers, such as temperature and pH, which can be utilized to stabilize and destabilize oil-water emulsions. By virtue of the modifications, these bifunctionalized CNCs diffused to the oil-water interface and stabilized the oil droplets at high pHs. When the pH was lowered to 2, strong hydrogen bonding between POEGMA and PMAA chains grafted on the CNC induced the coalescence of the emulsion droplets, resulting in the phase separation of oil and water. For emulsions stabilized by CNC-POEGMA and free PMAA mixtures, instantaneous coalescence was not observed at low pHs. Successive stabilization-destabilization over 5 cycles was demonstrated by modulating the pH with the addition of acid or base without any loss in efficiency. This work demonstrates that functional sustainable nanomaterials can be used for small scale oil-water separations, particularly for oil droplet transportation and harvesting of lipophilic compounds.

Temperature-responsive mixed core nanoparticle properties determined by the composition of statistical and block copolymers in the core

Mixed core nanoparticles were prepared from self-assembled statistical and block copolymers by controlling the solution temperature. Interestingly, an equal mass of specific statistical copolymers was successfully loaded into block copolymer micelle cores.

Bioinspired nanoarchitectonics as emerging drug delivery systems

Bioinspired nanoarchitectonics opens a new era for designing drug delivery systems.