Physicochemical Properties and Biological Performance of Polymethacrylate Based Gene Delivery Vector Systems: Influence of Amino Functionalities

Physicochemical characteristics and biological performance of polyplexes based on two identical copolymers bearing tertiary amino or quaternary ammonium groups are evaluated and compared. Poly(2-(dimethylamino)ethyl methacrylate)-b-poly(oligo(ethylene glycol) methyl ether methacrylate) block copolymer (PDMAEMA-b-POEGMA) is synthesized by reversible addition fragmentation chain transfer polymerization. The tertiary amines of PDMAEMA are converted to quaternary ammonium groups by quaternization with methyl iodide. The two copolymers spontaneously formed well-defined polyplexes with DNA. The size, zeta potential, molar mass, aggregation number, and morphology of the polyplex particles are determined. The parent PDMAEMA-b-POEGMA exhibits larger buffering capacity, whereas the corresponding quaternized copolymer (QPDMAEMA-b-POEGMA) displays stronger binding affinity to DNA, yielding invariably larger in size and molar mass particles bearing greater number of DNA molecules per particle. Experiments revealed that QPDMAEMA-b-POEGMA is more effective in transfecting pEGFP-N1 than the parent copolymer, attributed to the larger size, molar mass, and DNA cargo, as well as to the effective cellular traffic, which dominated over the enhanced ability for endo-lysosomal escape of PDMAEMA-b-POEGMA.

Construction of traceable cucurbit[7]uril-based virus-mimicking quaternary complexes with aggregation-induced emission for efficient gene transfection

Construction of an efficient cationic gene delivery system with low cytotoxicity, high transfection efficacy, as well as gene tracking function remains a major challenge in gene therapy. Fabrication of simple and reversible nanocomplexes based on host-guest interaction provides an opportunity to construct stimuli-responsive intelligent supramolecular systems. Inspired by the hierarchical structure of viruses, a novel virus-mimicking PG/CB/TPE/DNA gene delivery system is developed via a multistep noncovalent self-assembly process between pDNA and the preformed PG/CB/TPE complexes based on the host-guest interaction between cucurbit[7]uril (CB[7]) and the protonated diamine group in the poly(glycidyl methacrylate)s derivative (PG), as well as the electrostatic interaction between para-carboxyl functionalized tetraphenylethylene (TPE) and cationic PG. The developed efficient multifunctional gene delivery system exhibits stimuli responsive characteristics and aggregation-induced emission phenomena, thereby enabling gene delivery pH responsiveness and traceability. Moreover, the introduction of TPE and CB[7] endows the self-assembled PG/CB/TPE/DNA complexes with virus-mimicking architecture and properties such as low cytotoxicity, high stability, excellent endosomal escape, and efficient transfection, which are expected to be used as a promising gene delivery system.

Hydrolytically Labile Linkers Regulate Release and Activity of Human Bone Morphogenetic Protein-6

Release of growth factors while simultaneously maintaining their full biological activity over a period of days to weeks is an important issue in controlled drug delivery and in tissue engineering. In addition, the selected strategy to immobilize growth factors largely determines their biological activity. Silica surfaces derivatized with glycidyloxy propyl trimethoxysilane and poly(glycidyl methacrylate) brushes yielded epoxide-functionalized surfaces onto which human bone morphogenetic protein-6 (hBMP-6) was immobilized giving stable secondary amine bonds. The biological activity of hBMP-6 was unleashed by hydrolysis of the surface siloxane and ester bonds. We demonstrate that this type of labile bonding strategy can be applied to biomaterial surfaces with relatively simple and biocompatible chemistry, such as siloxane, ester, and imine bonds. Our data indicates that the use of differential hydrolytically labile linkers is a versatile method for functionalization of biomaterials with a variety of growth factors providing control over their biological activity.

Poly(glycerol methacrylate)-based degradable nanoparticles for delivery of small interfering RNA

Nucleic acids therapeutic efficiency is generally limited by their low stability and intracellular bioavailability, and by the toxicity of the carriers used to deliver them to the target sites. Aminated poly(glycerol methacrylate) polymers are biodegradable and pH-sensitive polymers that have been used previously to deliver antisense oligonucleotide and show high transfection efficiency. The purpose of this study is to compare the efficiency and toxicity of aminated linear poly(glycerol methacrylate) (ALT) biodegradable polymer to the most commonly used cationic degradable (i.e. chitosan) and non-degradable (i.e. polyethylenimine (PEI)) polymers for delivery of short interfering RNA (siRNA). ALT, PEI and chitosan polymers were able to form nanosized particles with siRNA. Size, size-distribution and zeta-potential were measured over a wide range of nitrogen-to-phosphate (N/P) ratios, and the stability of the formed nanoparticles in saline and upon freeze-drying was also assessed. No significant cytotoxicity at the range of the tested concentrations of ALT and chitosan nanoparticles was observed, whereas the non-degradable PEI showed significant toxicity in huh-7 hepatocyte-derived carcinoma cell line. The safety profiles of the degradable polymers (ALT and chitosan) over non-degradable PEI were demonstrated in vitro and in vivo. In addition, ALT nanoparticles were able to deliver siRNA in vivo with significantly higher efficiency than chitosan nanoparticles. The results in the present study give evidence of the great implications of ALT nanoparticles in biomedical applications due to their biocompatibility, low cytotoxicity, high stability and simple preparation method.

Construction of Supramolecular Nanoassembly for Responsive Bacterial Elimination and Effective Bacterial Detection

There is an urgent need for developing novel strategies for bacterial detection and inhibition. Herein, a multifunctional nanomaterial based on mesoporous silica nanoparticles (MSNs) is designed, loaded with amoxicillin (AMO), and surface-coated with 1,2-ethanediamine (EDA)-modified polyglycerol methacrylate (PGEDA), cucurbit[7]uril (CB[7]), and tetraphenylethylene carboxylate derivatives (TPE-(COOH)₄) by the layer-by-layer (LbL) self-assembly technique. When bacteria contacts with this nanoassembly, the binding of anionic bacterial surface toward the cationic PGEDA layer of this material can reduce or break the interactions between PGEDA layer and TPE-(COOH)₄ layer, leading to attenuated TPE-(COOH)₄ emission due to the weakening of aggregation-induced emission (AIE) effect. Furthermore, upon adding adamantaneamine (AD), the more stable AD⊂CB[7] complex forms and PGEDA is liberated through competitive replacement, thus leading to the release of AMO and resulting in much higher antibacterial ability of this nanomaterial. This newly designed nanomaterial possesses dual functions of controllable antibacterial activity against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli, and bacterial detection ability in aqueous media, suggesting that the design of this multifunctional antibacterial material will provide a simple, effective, and rapid way to control the activity of antimicrobial and open up an alternative new avenue for bacterial detection and elimination.

Post-polymerization modification reactions of poly(glycidyl methacrylate)s

Single and multiple post-polymerization modifications of poly(glycidyl methacrylate) scaffold through the nucleophilic ring-opening reactions of the pendent epoxide groups are described.

A dendritic catiomer with an MOF motif for the construction of safe and efficient gene delivery systems

The dendritic catiomer using biocompatible Zr-MOFs as the core exhibited a markedly higher transfection efficiency and lower cytotoxicity than the commercial gold standard branched PEI_25k in A549 cells.

Shedding PEG Palisade by Temporal Photostimulation and Intracellular Reducing Milieu for Facilitated Intracellular Trafficking and DNA Release

The dilemma of poly(ethylene glycol) surface modification (PEGylation) inspired us to develop an intracellularly sheddable PEG palisade for synthetic delivery systems. Here, we attempted to conjugate PEG to polyethylenimine (PEI) through tandem linkages of disulfide-bridge susceptible to cytoplasmic reduction and an azobenzene/cyclodextrin inclusion complex responsive to external photoirradiation. The subsequent investigations revealed that facile PEG detachment could be achieved in endosomes upon photoirradiation, consequently engendering exposure of membrane-disruptive PEI for facilitated endosome escape. The liberated formulation in the cytosol was further subjected to complete PEG detachment relying on disulfide cleavage in the reductive cytosol, thus accelerating dissociation of electrostatically assembled PEI/DNA polyplex to release DNA by means of polyion exchange reaction with intracellularly charged species, ultimately contributing to efficient gene expression.

Tuning the growth, crosslinking, and gating effect of disulfide-containing PGMAs on the surfaces of mesoporous silica nanoparticles for redox/pH dual-controlled cargo release

PGMA brushes grown on MSN surfaces via SI-ATRP could be cross-linked by cystamine or through a KI/H₂O₂ (30%) assisted disulfide bond exchange to realize gating effects for redox/pH dual-controlled cargo release.

A light and reduction dual sensitive supramolecular self-assembly gene delivery system based on poly(cyclodextrin) and disulfide-containing azobenzene-terminated branched polycations

Light and reduction sensitive supramolecular host–guest gene vectors can regulate gene release upon exposure to reduction environments and light radiation inside cells.

Aggregation-Induced-Emissive Molecule Incorporated into Polymeric Nanoparticulate as FRET Donor for Observing Doxorubicin Delivery

Tetraphenylethene (TPE) derivatives characterized with distinct aggregation-induced-emission, attempted to aggregate with doxorubicin (Dox) to formulate the interior compartment of polymeric nanoparticulate, served as fluorescence resonance energy transfer (FRET) donor to promote emission of acceptor Dox. Accordingly, this FRET formulation allowed identification of Dox in complexed form by detecting FRET. Important insight into the Dox releasing can be subsequently explored by extracting complexed Dox (FRET) from the overall Dox via direct single-photon excitation of Dox. Of note, functional catiomers were used to complex with FRET partners for a template formulation, which was verified to induce pH-responsive release in the targeted subcellular compartment. Hence, this well-defined multifunctional system entitles in situ observation of the drug releasing profile and insight on drug delivery journey from the tip of injection vein to the subcellular organelle of the targeted cells.

Layer-by-Layer (LBL) Self-Assembled Biohybrid Nanomaterials for Efficient Antibacterial Applications

Although antibiotics have been widely used in clinical applications to treat pathogenic infections at present, the problem of drug-resistance associated with abuse of antibiotics is becoming a potential threat to human beings. We report a biohybrid nanomaterial consisting of antibiotics, enzyme, polymers, hyaluronic acid (HA), and mesoporous silica nanoparticles (MSNs), which exhibits efficient in vitro and in vivo antibacterial activity with good biocompatibility and negligible hemolytic side effect. Herein, biocompatible layer-by-layer (LBL) coated MSNs are designed and crafted to release encapsulated antibiotics, e.g., amoxicillin (AMO), upon triggering with hyaluronidase, produced by various pathogenic Staphylococcus aureus (S. aureus). The LBL coating process comprises lysozyme (Lys), HA, and 1,2-ethanediamine (EDA)-modified polyglycerol methacrylate (PGMA). The Lys and cationic polymers provided multivalent interactions between MSN-Lys-HA-PGMA and bacterial membrane and accordingly immobilized the nanoparticles to facilitate the synergistic effect of these antibacterial agents. Loading process was characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and X-ray diffraction spectroscopy (XRD). The minimal inhibition concentration (MIC) of MSN-Lys-HA-PGMA treated to antibiotic resistant bacteria is much lower than that of isodose Lys and AMO. Especially, MSN-Lys-HA-PGMA exhibited good inhibition for pathogens in bacteria-infected wounds in vivo. Therefore, this type of new biohybrid nanomaterials showed great potential as novel antibacterial agents.

Homopolymer bifunctionalization through sequential thiol–epoxy and esterification reactions: an optimization, quantification, and structural elucidation study

In this study, we probe various aspects of a post-polymerization double-modification strategy involving sequential thiol–epoxy and esterification reactions for the preparation of dual-functional homopolymers.

Dual functionalized amino poly(glycerol methacrylate) with guanidine and Schiff-base linked imidazole for enhanced gene transfection and minimized cytotoxicity

Guanidine and Schiff-base linked imidazole dual functionalized poly(glycerol methacrylate) (IGEP) leads to minimized cytotoxicity and better transfection efficacy than PEI_25K.

Mesoporous Silica Nanoparticles Coated by Layer-by-Layer Self-assembly Using Cucurbit[7]uril for in Vitro and in Vivo Anticancer Drug Release

Mesoporous silica nanoparticles (MSNs) are promising solid supports for controlled anticancer drug delivery. Herein, we report biocompatible layer-by-layer (LbL) coated MSNs (LbL-MSNs) that are designed and crafted to release encapsulated anticancer drugs, e.g., doxorubicin hydrochloride (DOX), by changing the pH or by adding competitive agents. The LbL coating process comprises bis-aminated poly(glycerol methacrylate)s (BA-PGOHMAs) and cucurbit[7]uril (CB[7]), where CB[7] serves as a molecular bridge holding two different bis-aminated polymeric layers together by means of host-guest interactions. This integrated nanosystem is tuned to respond under specific acidic conditions or by adding adamantaneamine hydrochloride (AH), attributed to the competitive binding of hydronium ions or AH to CB[7] with BA-PGOHMAs. These LbL-MSN hybrids possess excellent biostability, negligible premature drug leakage at pH 7.4, and exceptional stimuli-responsive drug release performance. The pore sizes of the MSNs and bis-aminated compounds (different carbon numbers) of BA-PGOHMAs have been optimized to provide effective integrated nanosystems for the loading and release of DOX. Significantly, the operating pH for the controlled release of DOX matches the acidifying endosomal compartments of HeLa cancer cells, suggesting that these hybrid nanosystems are good candidates for autonomous anticancer drug nanocarriers actuated by intracellular pH changes without any invasive external stimuli. The successful cellular uptake and release of cargo, e.g., propidium iodide (PI), in human breast cancer cell line MDA-231 from PI-loaded LbL-MSNs have been confirmed by confocal laser scanning microscopy (CLSM), while the cytotoxicities of DOX-loaded LbL-MSNs have been quantified by the Cell Counting Kit-8 (CCK-8) viability assay against HeLa cell lines and fibroblast L929 cell lines. The uptake of DOX-loaded LbL-MSNs by macrophages can be efficiently reduced by adding biocompatible hydrophilic poly(ethylene glycol) or CB[7] without destroying the capping. In vivo tumor-growth inhibition experiments with BALB/c nude mice demonstrated a highly efficient tumor-growth inhibition rate of DOX-loaded LbL-MSNs, suggesting that the novel type of LbL-MSN materials hold great potentials in anticancer drug delivery.

New low molecular weight polycation-based nanoparticles for effective codelivery of pDNA and drug

The development of new cationic nanoparticles that are safe and effective for biomedical applications has attracted considerable attention. Low molecular weight polycations generally exhibit low toxicity; however, their poor efficiency in drug delivery systems hampers their application. In this work, a series of new low molecular weight 2,6-bis(1-methylbenzimidazolyl)pyridinyl (BIP)-terminated ethanolamine-functionalized poly(glycidyl methacrylate)s (BIP-PGEAs) were readily fabricated for effective codelivery of a gene and a drug. The BIP-PGEAs could form well-defined cationic nanoparticles (NPs) in an aqueous solution. They could effectively bind pDNA with an appropriate particle size and ζ-potential. More importantly, the BIP-PGEA NPs demonstrated much higher transfection efficiencies than linear PGEA (L-PGEA) and the traditional "gold-standard" branched polyethylenimine (25 kDa). Moreover, the BIP-PGEA NPs could effectively entrap a hydrophobic anticancer drug such as 10-hydroxy camptothecin (CPT). The synergistic antitumor effect of the BIP-PGEA-CPT NPs was demonstrated by employing a suicide gene therapy system, which contained cytosine deaminase and 5-fluorocytosine (CD/5-FC). The present strategy for preparing well-defined cationic nanoparticles from low-molecular-weight polycations could provide an intriguing method to produce new multifunctional, therapeutic NPs.

Oligoamine-tethered low generation polyamidoamine dendrimers as potential nucleic acid carriers

Oligoamine-tethered low generation PAMAM dendrimers (mG2–mG4) have been synthesized, which showed significantly higher transfection efficiency with minimal cytotoxicity in vitro.

Construction of reverse vesicles from pseudo-graft poly(glycerol methacrylate)s via cyclodextrin–cholesterol interactions

Reverse vesicles were constructed from pseudo-graft amphiphilic copolymers by dint of the host–guest inclusion complexation between β-cyclodextrins and cholesterols, and transformed into organogels by adding trace amounts of water.