Polyethylenimine-polyacrylic acid nanocomposites: Type of bonding does influence the gene transfer efficacy and cytotoxicity

Optimization of Mixed Micelles Based on Oppositely Charged Block Copolymers by Machine Learning for Application in Gene Delivery

The COVID-19 mRNA vaccines represent a milestone in developing non-viral gene carriers, and their success highlights the crucial need for continued research in this field to address further challenges. Polymer-based delivery systems are particularly promising due to their versatile chemical structure and convenient adaptability, but struggle with the toxicity-efficiency dilemma. Introducing anionic, hydrophilic, or "stealth" functionalities represents a promising approach to overcome this dilemma in gene delivery. Here, two sets of diblock terpolymers are created comprising hydrophobic poly(n-butyl acrylate) (PnBA), a copolymer segment made of hydrophilic 4-acryloylmorpholine (NAM), and either the cationic 3-guanidinopropyl acrylamide (GPAm) or the 2-carboxyethyl acrylamide (CEAm), which is negatively charged at neutral conditions. These oppositely charged sets of diblocks are co-assembled in different ratios to form mixed micelles. Since this experimental design enables countless mixing possibilities, a machine learning approach is applied to identify an optimal GPAm/CEAm ratio for achieving high transfection efficiency and cell viability with little resource expenses. After two runs, an optimal ratio to overcome the toxicity-efficiency dilemma is identified. The results highlight the remarkable potential of integrating machine learning into polymer chemistry to effectively tackle the enormous number of conceivable combinations for identifying novel and powerful gene transporters.

A Sol-Gel Transition and Self-Healing Hydrogel Triggered via Photodimerization of Coumarin

Reversible chemical covalency provides a path to materials that can degrade and recombine with appropriate stimuli and which can be used for tissue regeneration and repair. However, designing and preparing efficient and quickly self-healing materials has always been a challenge. The preparation strategies of photoresponsive gels attract a lot of attention due to their precise spatial and temporal control and their predetermined response to light stimulation. In this work, the linear copolymer PAC was synthesized via precipitation polymerization of acrylic acid and 7-(2-acrylate-ethoxylated)-4-methylcoumarin. The coumarin groups on the copolymer PAC side chains provide a reversible chemical cross-linking via photostimulation, which achieves reversible regulation of the gel network structure. The concentration of 18 wt% PAC solution produces gelation under irradiation with 365 nm. In contrast, PAC gel is restored to soluble copolymers under irradiation with 254 nm. Meanwhile, the mechanical and self-healing properties of the gel were also explored. It is demonstrated that the cracks of the gel can be repaired simply, quickly, and efficiently. Furthermore, the PAC copolymer shows an excellent adhesion property based on the reversible sol-gel transition. Thus, the PAC gel has considerable potential for applications in engineering and biomedical materials.

Benzeneboronic-alginate/quaternized chitosan-catechol powder with rapid self-gelation, wet adhesion, biodegradation and antibacterial activity for non-compressible hemorrhage control

Although hemostatic powders have excellent adaptability for irregular and inaccessible wounds, their hemostasis for continuous bleeding or bleeding wounds of non-compressible organs remains a critical challenge. Herein, a series of benzeneboronic acid-modified sodium alginate/catechol-modified quaternized chitosan (SA-BA/QCS-C, SBQCC) powders is developed by borate ester crosslinking for non-compressible hemorrhage control. SBQCC powders possess remarkable tissue adhesion, rapid self-gelation, good cytocompatibility and antibacterial activity against S. aureus and E. coil. The blood coagulation assays show that SBQCC powders display excellent blood clotting ability due to the synergistic effect of SA-BA and QCS-C. The SBQCC2 powder with the SA-BA to QCS-C mass ratio of 5 to 3 has the greatest effect on the blood-clotting rate. Upon depositing SBQCC2 powder to bleeding wounds of rabbit liver, the powder can absorb a large amount of blood and form a stable hydrogel physical barrier at the bleeding wounds in situ to achieve non-pressing rapid hemostasis. The SBQCC2 powder also has good biocompatibility and can be degraded in vivo. Altogether, the SBQCC powders can be a promising candidate for rapid hemostasis, and these findings may provide a new perspective for improving the hemostatic efficiency of the hemostatic powder in biomedical fields.

Triton modified polyethyleneimine conjugates assembled with growth arrest-specific protein 6 for androgenetic alopecia transdermal gene therapy

Androgenetic alopecia is an androgen-dependent skin disorder that commonly affects hair follicle growth and hair loss. Gene therapy that can promote the proliferation and survival of hair follicle cells can be a potential choice for its cure. While transdermal application of therapeutic functional nucleic acids across the stratum corneum is quite difficult. Here, we first develop a transdermal agent for functional nucleic acid delivery using Triton X-100-modified low molecular weight polyethyleneimine (PEI-Triton-N, N ​= ​6 or 8). In vitro cell experiments demonstrate that the PEI-Triton-N conjugates can stably encapsulate and efficiently deliver plasmid DNA to hard-to-transfect keratinocyte HaCaT cells. Further mouse model studies show that PEI-Triton-6 can encapsulate and deliver growth arrest-specific protein 6 (Gas6) plasmid through transdermal administration. The transfected Gas6 prolongs the anagen status, inhibits the apoptosis of hair follicle cells, and further promotes the proliferation and differentiation of hair follicle cells. The PEI-Triton-6/pDNA_Gas6 complexes can obviously alleviate hair loss in androgenetic alopecia mice and provides a promising strategy for gene therapy via transdermal administration.

Development of a magnetic nanoparticle-based method for concentrating SARS-CoV-2 in wastewater

Several virus concentration methods have been developed to increase the detection sensitivity of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in wastewater, as part of applying wastewater-based epidemiology. Polyethylene glycol (PEG) precipitation method, a method widely used for concentrating viruses in wastewater, has some limitations, such as long processing time. In this study, Pegcision, a PEG-based method using magnetic nanoparticles (MNPs), was applied to detect SARS-CoV-2 in wastewater, with several modifications to increase its sensitivity and throughput. An enveloped virus surrogate, Pseudomonas phage φ6, and a non-enveloped virus surrogate, coliphage MS2, were seeded into wastewater samples and quantified using reverse transcription-quantitative polymerase chain reaction to assess the recovery performance of the Pegcision. Neither increasing MNP concentration nor reducing the reaction time to 10 min affected the recovery, while adding polyacrylic acid as a polyanion improved the detection sensitivity. The performance of the Pegcision was further compared to that of the PEG precipitation method based on the detection of SARS-CoV-2 and surrogate viruses, including indigenous pepper mild mottle virus (PMMoV), in wastewater samples (n = 27). The Pegcision showed recovery of 14.1 ± 6.3 % and 1.4 ± 1.0 % for φ6 and MS2, respectively, while the PEG precipitation method showed recovery of 20.4 ± 20.2 % and 18.4 ± 21.9 % (n = 27 each). Additionally, comparable PMMoV concentrations were observed between the Pegcision (7.9 ± 0.3 log copies/L) and PEG precipitation methods (8.0 ± 0.2 log copies/L) (P > 0.05) (n = 27). SARS-CoV-2 RNA was successfully detected in 11 (41 %) each of 27 wastewater samples using the Pegcision and PEG precipitation methods. The Pegcision showed comparable performance with the PEG precipitation method for SARS-CoV-2 RNA concentration, suggesting its applicability as a virus concentration method.

Mannosylated poly(acrylic acid)-coated mesoporous silica nanoparticles for anticancer therapy

Although mesoporous silica nanoparticles (MSNs) are widely used as anticancer drug carriers, unmodified MSNs induce off-target effects and at high doses, there are adverse effects of hemolysis because of the interaction with the silanol group on the surface and cells. In this study, we developed doxorubicin (DOX)-loaded MSNs coated with mannose grafted poly (acrylic acid) copolymer (DOX@MSNs-man-g-PAA) to enhance the hemocompatibility and target efficacy to cancer cells. This uniform nanosized DOX@MSNs-man-g-PAA showed sustained and pH-dependent drug release with improved hemocompatibility over the bare MSNs. The uptake of the DOX@MSN-man-g-PAA in breast cancer cells was significantly improved by mannose receptor-mediated endocytosis, which showed significant increasing intracellular ROS and changes in mitochondrial membrane potential. This formulation exhibited superior tumor-suppressing activity in the MDA-MB-231 cells inoculated mice. Overall, the present study suggested the possibility of the copolymer-coated MSNs as drug carriers for cancer therapy.

In Vitro Cytotoxicity and Cytokine Production by Lipid-Substituted Low Molecular Weight Branched PEIs Used for Gene Delivery

Lipid-modified low molecular weight branched polyethyleneimines (PEIs) are promising non-viral gene delivery systems that have been successfully explored for treatment of various diseases. The present study aims to determine in vitro safety of these delivery systems based on assessment of cytotoxicity with peripheral blood mononuclear cells (PBMCs), hemolysis with human red blood cells (RBC) and cytokine secretion from several sources of PBMCs. The viability of cells treated with lipopolymer/pDNA complexes was dependent on the polymer:pDNA ratio used but remained low at therapeutically relevant concentrations for most lipopolymers, except for the propionic acid substituted PEIs. The extent of hemolysis was minimal and below the accepted safety levels with most of the lipopolymers; however, some linoleic acid substituted PEIs yielded significant hemolysis activity. Unlike strong cytokine secretion from PMA/IO stimulated cells, most lipopolymer/pDNA complexes remained non-responsive, showing minimal changes in cytokine secretion (TNF-α, IL-6 and IFN-γ) irrespective of the lipopolymer/pDNA formulations. The 0.6 kDa PEI with lauric acid substituent displayed slight cytokine upregulation, however it remained low relative to the positive controls. This study demonstrated that the lipid modified LMW PEIs are expected to be safe in contact with blood components. However, close attention to lipopolymer concentration and ratio of polymer to pDNA in formulations might be required for individual lipopolymers for optimal safety response in nucleic acid therapies. STATEMENT OF SIGNIFICANCE: : This manuscript investigated the safety aspects of various lipid modified low molecular weight polyethylenimine (LMW-PEI) polymers employed for pDNA delivery through in vitro studies. Using peripheral blood mononuclear cells (PBMCs) from multiple sources, we show that the hemolysis ability was minimal for most polymers, although a particular lipid substituent (linoleic acid) at specific ratios exhibited hemolysis. The levels of pro-inflammatory cytokines (TNF-α, IL-6 and IFN-γ) were slightly upregulated only with a lauric acid substituted 0.6PEI, but remained low relative to positive control treatments. We further report the beneficial effect of polyacrylic acid additives on hemolysis and cytokine secretion to a reasonable extent. This study confirms the feasibility of using LMW-PEI as safe delivery agents for various therapeutic purposes.

Self-coagulating polyelectrolyte complexes for target-tunable adsorption and separation of metal ions

Metal-containing wastes in aquatic environments lead to public health hazards and valuable resource lose. Metal-bearing wastewater must be treated to remove heavy metals or recover precious metals. To achieve these, target-tunable adsorbents that bind cationic and anionic metal species were developed through facile polyelectrolyte complexation using polyethylenimine (PEI) and polyacrylic acid (PAA). Utilizing the properties of the two polyelectrolytes and pK_a variabilities, stable tunable adsorbents were fabricated in water without additional solvents. The homogenous complex adsorbents were strategically synthesized via dissolution in 0.1 M NaOH and drop-wise addition of 1 M HCl, followed by crosslinking with glutaraldehyde. Consequently, the adsorbents in alternating weight ratios of 4:1 and 1:4 (PEI:PAA) exhibited good tunability and adsorption properties. The maximum single metal adsorption capacities were 1609.7 ± 49.6 and 558.6 ± 9.67 mg/g for gold and cadmium, respectively. The pseudo-second-order model fitted the kinetics data more appropriately and was recognized as the rate controlling step. In a binary mixture, gold selectivity was observed to be influenced by adsorption-reduction mechanism, which was elucidated by XRD and XPS. Moreover, the adsorbents demonstrated NO₃- sequestration properties, a feat deemed important for environmental remediation of nitrate ions. Finally, sequential separation was achieved with ethylenediaminetetraacetic acid (EDTA) and acidified thiourea.

Fe3O4 composited with MoS2 blocks horizontal gene transfer

In this study, we found that Fe₃O₄ promoted horizontal gene transfer (HGT), but when Fe₃O₄ was composited with MoS₂, the Fe₃O₄@MoS₂ nanocomposite interacting with bacteria significantly blocked the HGT in the conjugation system. qPCR was used to analyze the expression of genes belonging to the chromosome and plasmid in the conjugation system. Results demonstrated that Fe₃O₄@MoS₂ inhibited conjugation by promoting the expression of the global regulatory gene (trbA) and inhibiting the expression of conjugative transfer genes involved in mating pair formation (traF, trbB), DNA replication (trfA), and porins (outer membrane protein (omp) A and ompC). All of these genes are related to the permeability of the cell membrane, except for trfA. The results showed that Fe₃O₄@MoS₂ interacted with bacteria to decrease their permeability against exogenous DNA. MoS₂ may play an essential role in the HGT-inhibiting activity of Fe₃O₄@MoS₂. This study highlights the diverse biological properties of nano-materials and provides clues for nano-scientists to develop environmentally friendly materials.

Photolithographically assembled polyelectrolyte complexes as shape-directing templates for thermoreversible gels

Preparation of soft materials with diverse, customized shapes has been a topic of intense research interest. To this end, we have recently demonstrated photolithographic directed assembly as a strategy for customizing polyelectrolyte complex (PEC) shape. This process uses in situ photopolymerization of an anionic monomer in the presence of a cationic polymer, which drives localized PEC formation at the irradiation sites. Here, we show how such photolithographically assembled PECs can serve as structure-directing templates for tailoring the shapes of other soft materials; namely, thermoreversible gels. These templated hydrogels are prepared by adding a thermogelling polymer (agarose) to the anionic monomer/cationic polymer/photoinitiator precursor solutions so that, upon irradiation, custom-shaped PECs form within agarose gel matrices. Once these PECs are formed, the surrounding agarose gels are melted (through heating) and washed away which, upon returning the samples to room temperature, produces interpenetrating PEC/agarose gel networks with photopatterned shapes and dimensions. Dissolution of these sacrificial PEC templates in concentrated NaCl solutions then generates photolithographically templated agarose gels, whose shapes and dimensions match those of their PEC templates. Besides tuning their shapes and sizes, the mechanical properties of these gels can be easily tailored by varying the initial agarose concentrations used. Moreover, this PEC-templated gel synthesis appears to not adversely affect hydrogel cytocompatibility, suggesting its potential suitability for biological and biomedical applications. Though the present study uses only agarose as the model gel system, this PEC-based strategy for customizing gel shape can likely also be applied to other thermoreversible gel networks (e.g., those based on methylcellulose, poloxamers or thermoresponsive chitosan derivatives) and could have many attractive applications, ranging from drug delivery and tissue engineering, to sensing and soft robotics.

Cationized Bombyx mori silk fibroin as a delivery carrier of the VEGF165-Ang-1 coexpression plasmid for dermal tissue regeneration

The angiogenesis of an implanted construct is among the most important issues in tissue engineering. In this study, spermine was used to modify Bombyx mori silk fibroin (BSF) to synthesize cationized BSF (CBSF). BSF and CBSF were coated in sequence on the surface of polyethyleneimine (PEI)/vascular endothelial growth factor 165/angiopoietin-1 coexpression plasmid DNA (pDNA) complexes to form CBSF/BSF/PEI/pDNA quaternary complexes. BSF scaffolds loaded with carrier/pDNA complexes were prepared as dermal regeneration scaffolds by freeze-drying. In one set of experiments, scaffolds were used to cover a chick embryo chorioallantoic membrane (CAM) to investigate the influence of carrier/pDNA complexes on angiogenesis; in another set of experiments, scaffolds were implanted into dorsal full-thickness wounds in Sprague-Dawley rats to evaluate the effect of carrier/pDNA complex-loaded BSF scaffolds on neovascularization and dermal tissue regeneration. After modification with spermine, the surface zeta potential value of BSF rose to +11 mV from an initial value of -9 mV, and the isoelectric point of BSF increased from 4.20 to 9.04. The in vitro transfection of human umbilical vein endothelial cells (EA.hy926) with quaternary complexes revealed that the CBSF/BSF/PEI/pDNA complexes clearly exhibited lower cytotoxicity and higher transfection efficiency than the PEI/pDNA complexes. The CAM assay showed a more abundant branching pattern of blood vessels in BSF scaffolds loaded with CBSF/BSF/PEI/pDNA complexes than in BSF scaffolds without complexes or loaded with PEI/pDNA complexes. The in vivo experimental results demonstrated that the incorporation of CBSF/BSF/PEI/pDNA complexes could effectively enhance angiogenesis in the implanted BSF scaffolds, thereby promoting the regeneration of dermal tissue, providing a new scaffold for the regeneration of dermal tissue and other tissues containing blood vessels.

Polycation-telodendrimer nanocomplexes for intracellular protein delivery

Intracellular delivery of protein therapeutics by cationic polymer vehicles is an emerging technique that is, however, encountering poor stability, high cytotoxicity and non-specific cell uptake. Herein, we present a facile strategy to optimize the protein-polycation complexes by encapsulating with linear-dendritic telodendrimers. The telodendrimers with well-defined structures enable the rational design and integration of multiple functionalities for efficient encapsulation of the protein-polycation complexes by multivalent and hybrid supramolecular interactions to produce sub-20 nm nanoparticles. This strategy not only reduces the polycation-associated cytotoxicity and hemolytic activity, but also eliminates the aggregation and non-specific binding of polycations to other biomacromolecules. Moreover, the telodendrimers dissociate readily from the complexes during the cellular uptake process, which restores the capability of polycations for intracellular protein delivery. This strategy overcomes the limitations of polycationic vectors for intracellular delivery of protein therapeutics.

Synthesis of Polyethylenimine Functionalized Mesoporous Silica for In-Pipet-Tip Phosphopeptide Enrichment

Synthesis of functionalized mesoporous silica material with large particle size remains a chanllenge. In this work, polyethylenimine (PEI) functionalized mesoporous silica (PFMS) with particle size as large as 100 μm was successfully synthesized by a facile method. In the synthesis process, PEI served as four roles simultaneously, including functionalized reagent, alkaline catalyst, template for particle formation, and pore-structure-directing agent. The surface areas of the products were higher than 260 m²/g. Benefiting from the large particle size and high surface area, PFMS was packed in a pipet tip to fabricate a convenient and miniaturized solid phase extraction apparatus for sample preparation. Additionally, based on the extremely abundant basic sites in the organic units of PFMS, the in-pipet-tip system was used as an anion-exchanger for phosphopeptide enrichment. The specificity of the developed method was investigated by capture of phosphopeptides from tryptic digests of standard protein mixtures, tryptic digests of nonfat milk, and human serum. Furthermore, the method was utilized to analyze phosphopeptides in tryptic digests of rat brain lysate, and 2251 unique phosphopeptides were successfully detected.

pH-triggered sustained release of arsenic trioxide by polyacrylic acid capped mesoporous silica nanoparticles for solid tumor treatment in vitro and in vivo

Arsenic trioxide (As2O3, ATO), a FDA approved drug for hematologic malignancies, was proved of efficient growth inhibition of cancer cell in vitro or solid tumor in vivo. However, its effect on solid tumor in vivo was hampered by its poor pharmacokinetics and dose-limited toxicity. In this study, a polyacrylic acid capped pH-triggered mesoporous silica nanoparticles was conducted to improve the pharmacokinetics and enhance the antitumor effect of arsenic trioxide. The mesoporous silica nanoparticles loaded with arsenic trioxide was grafted with polyacrylic acid (PAA-ATO-MSN) as a pH-responsive biomaterial on the surface to achieve the release of drug in acidic microenvironment of tumor, instead of burst release action in circulation. The nanoparticles were characterized with uniform grain size (particle sizes of 158.6 ± 1.3 nm and pore sizes of 3.71 nm, respectively), historically comparable drug loading efficiency (11.42 ± 1.75%), pH-responsive and strengthened sustained release features. The cell toxicity of amino groups modified mesoporous silica nanoparticles (NH2-MSN) was significantly reduced by capping of polyacrylic acid. In pharmacokinetic studies, the half time (t1/2β) was prolonged by 1.3 times, and the area under curve) was increased by 2.6 times in PAA-ATO-MSN group compared with free arsenic trioxide group. Subsequently, the antitumor efficacy in vitro (SMMC-7721 cell line) and in vivo (H22 xenografts) was remarkably enhanced indicated that PAA-ATO-MSN improved the antitumor effect of the drug. These results suggest that the polyacrylic acid capped mesoporous silica nanoparticles (PAA-MSN) will be a promising nanocarrier for improving pharmacokinetic features and enhancing the anti-tumor efficacy of arsenic trioxide.