Synthesis of Stimuli-Responsive Heterofunctional Dendrimer by Passerini Multicomponent Reaction

Cationic lipids from multi-component Passerini reaction for non-viral gene delivery: A structure-activity relationship study

Although many types of cationic lipids have been developed as efficient gene vectors, the construction of lipid molecules with simple procedures remains challenging. Passerini reaction, as a classic multicomponent reaction, could directly give the α-acyloxycarboxamide products with biodegradable ester and amide bonds. Herein, two series of novel cationic lipids with heterocyclic pyrrolidine and piperidine as headgroups were synthesized through Passerini reaction (P-series) and amide condensation (A-series), and relevant structure-activity relationships on their gene delivery capability was studied. It was found that although both of the two series of lipids could form lipid nanoparticles (LNPs) which could effectively condense DNA, the LNP derived from P-series lipids showed higher transfection efficiency, serum tolerance, cellular uptake, and lower cytotoxicity. Unlike the A-series LNPs, the P-series LNPs showed quite different structure-activity relationship, in which the relative site of the secondary amine had significant effect on the transfection performance. The othro-isomers of the P-series lipids had lower cytotoxicity, but poor transfection efficiency, which was probably due to their unstable nature. Taken together, this study not only validated the feasibility of Passerini reaction for the construction of cationic lipids for gene delivery, but also afforded some clues for the rational design of effective non-viral lipidic gene vectors.

Next-Generation Nanomedicine Approaches for the Management of Retinal Diseases

Retinal diseases are one of the leading causes of blindness globally. The mainstay treatments for these blinding diseases are laser photocoagulation, vitrectomy, and repeated intravitreal injections of anti-vascular endothelial growth factor (VEGF) or steroids. Unfortunately, these therapies are associated with ocular complications like inflammation, elevated intraocular pressure, retinal detachment, endophthalmitis, and vitreous hemorrhage. Recent advances in nanomedicine seek to curtail these limitations, overcoming ocular barriers by developing non-invasive or minimally invasive delivery modalities. These modalities include delivering therapeutics to specific cellular targets in the retina, providing sustained delivery of drugs to avoid repeated intravitreal injections, and acting as a scaffold for neural tissue regeneration. These next-generation nanomedicine approaches could potentially revolutionize the treatment landscape of retinal diseases. This review describes the availability and limitations of current treatment strategies and highlights insights into the advancement of future approaches using next-generation nanomedicines to manage retinal diseases.

Telodendrimers: Promising Architectural Polymers for Drug Delivery

Architectural complexity has played a key role in enhancing the efficacy of nanocarriers for a variety of applications, including those in the biomedical field. With the continued evolution in designing macromolecules-based nanoparticles for drug delivery, the combination approach of using important features of linear polymers with dendrimers has offered an advantageous and viable platform. Such nanostructures, which are commonly referred to as telodendrimers, are hybrids of linear polymers covalently linked with different dendrimer generations and backbones. There is considerable variety in selection from widely studied linear polymers and dendrimers, which can help tune the overall composition of the resulting hybrid structures. This review highlights the advances in articulating syntheses of these macromolecules, and the contributions these are making in facilitating therapeutic administration. Limited progress has been made in the design and synthesis of these hybrid macromolecules, and it is through an understanding of their physicochemical properties and aqueous self-assembly that one can expect to fully exploit their potential in drug delivery.

Photo- and pH-Responsive Polycarbonate Block Copolymer Prodrug Nanomicelles for Controlled Release of Doxorubicin

Photo/pH dual-responsive amphiphilic diblock copolymers with alkyne functionalized pendant o-nitrobenzyl ester group are synthesized using poly(ethylene glycol) as a macroinitiator. The pendant alkynes are functionalized as aldehyde groups by the azide-alkyne Huisgen cycloaddition. The anticancer drug doxorubicin (DOX) molecules are then covalently conjugated through acid-sensitive Schiff-base linkage. The resultant prodrug copolymers self-assemble into nanomicelles in aqueous solution. The prodrug nanomicelles have a well-defined morphology with an average size of 20-40 nm. The dual-stimuli are applied individually or simultaneously to study the release behavior of DOX. Under UV light irradiation, nanomicelles are disassembled due to the ONB ester photocleavage. The light-controlled DOX release behavior is demonstrated using fluorescence spectroscopy. Due to the pH-sensitive imine linkage the DOX molecules are released rapidly from the nanomicelles at the acidic pH of 5.0, whereas only minimal amount of DOX molecules is released at the pH of 7.4. The DOX release rate is tunable by applying the dual-stimuli simultaneously. In vitro studies against colon cancer cells demonstrate that the nanomicelles show the efficient cellular uptake and the intracellular DOX release, indicating that the newly designed copolymers with dual-stimuli-response have significant potential applications as a smart nanomedicine against cancer.

Dendrimers: Amazing Platforms for Bioactive Molecule Delivery Systems

Today, dendrimers are the main nanoparticle applied to drug delivery systems. The physicochemical characteristics of dendrimers and their versatility structural modification make them attractive to applied as a platform to bioactive molecules transport. Nanoformulations based on dendrimers enhance low solubility drugs, arrival to the target tissue, drugs bioavailability, and controlled release. This review describes the latter approaches on the transport of bioactive molecules based on dendrimers. The review focus is on the last therapeutic strategies addressed by dendrimers conjugated with bioactive molecules. A brief review of the latest studies in therapies against cancer and cardiovascular diseases, as well as future projections in the area, are addressed.

Multi-stimuli-responsive nanomicelles fabricated using synthetic polymer polylysine conjugates for tumor microenvironment dependent drug delivery

A poly(lysine)-synthetic polymer hybrid nanomicelles were fabricated as promising platform for efficient tumor targeting and glutathione/pH/temperature-responsive anticancer drug delivery.

Ag2O-catalysed nucleophilic isocyanation: selective formation of less-stable benzylic isonitriles

Both primary and secondary benzylic isonitriles were exclusively produced by the Ag₂O-catalysed reaction of benzylic phosphates and trimethylsilyl cyanide without formation of the thermodynamically favoured regioisomers, benzylic nitriles.

Recent Progress and Advances of Multi-Stimuli-Responsive Dendrimers in Drug Delivery for Cancer Treatment

Despite the fact that nanocarriers as drug delivery systems overcome the limitation of chemotherapy, the leakage of encapsulated drugs during the delivery process to the target site can still cause toxic effects to healthy cells in other tissues and organs in the body. Controlling drug release at the target site, responding to stimuli that originated from internal changes within the body, as well as stimuli manipulated by external sources has recently received significant attention. Owning to the spherical shape and porous structure, dendrimer is utilized as a material for drug delivery. Moreover, the surface region of dendrimer has various moieties facilitating the surface functionalization to develop the desired material. Therefore, multi-stimuli-responsive dendrimers or 'smart' dendrimers that respond to more than two stimuli will be an inspired attempt to achieve the site-specific release and reduce as much as possible the side effects of the drug. The aim of this review was to delve much deeper into the recent progress of multi-stimuli-responsive dendrimers in the delivery of anticancer drugs in addition to the major potential challenges.