Cytotoxicity of polyethyleneimine (PEI), precursor base layer of polyelectrolyte multilayer films

Synthesis and real-time characterization of self-healing, injectable, fast-gelling hydrogels based on alginate multi-reducing end polysaccharides (MREPs)

Polysaccharide-based hydrogels are promising for many biomedical applications including drug delivery, wound healing, and tissue engineering. We illustrate herein self-healing, injectable, fast-gelling hydrogels prepared from multi-reducing end polysaccharides, recently introduced by the Edgar group. Simple condensation of reducing ends from multi-reducing end alginate (M-Alg) with amines from polyethylene imine (PEI) in water affords a dynamic, hydrophilic polysaccharide network. Trace amounts of acetic acid can accelerate the gelation time from hours to seconds. The fast-gelation behavior is driven by rapid Schiff base formation and strong ionic interactions induced by acetic acid. A cantilever rheometer enables real-time monitoring of changes in viscoelastic properties during hydrogel formation. The reversible nature of these crosslinks (imine bonds, ionic interactions) provides a hydrogel with low toxicity in cell studies as well as self-healing and injectable properties. Therefore, the self-healing, injectable, and fast-gelling M-Alg/PEI hydrogel holds substantial promise for biomedical, agricultural, controlled release, and other applications.

Transforming the Stability, Encapsulation, and Sustained Release Properties of Calcium Alginate Beads through Gel-Confined Coacervation

Calcium alginate (Ca2+/alginate) gel beads find use in diverse applications, ranging from drug delivery and tissue engineering to bioprocessing, food formulation, and agriculture. Unless modified, however, these gels have limited stability in alkaline media (including phosphate buffers), and their high solute permeability limits their ability to efficiently encapsulate and slowly release water-soluble small molecules. Here, we show how these limitations can be addressed by mixing the alginate solutions used in the bead preparation with the nontoxic anionic polymer polyphosphate (PP). Upon complexing Ca2+ ions, PP undergoes complex coacervation (i.e., liquid/liquid phase separation into a Ca2+/PP-rich coacervate phase and a dilute supernatant phase). At lower PP concentrations, the Ca2+/PP coacervate appears to simply remain dispersed within the beads. Though its presence makes the beads more stable in alkaline media (phosphate-buffered saline and seawater), it has little impact on the bead stiffness, morphology, and (at least in the absence of substantial payload/coacervate association) encapsulation and release properties. When the PP concentrations exceed a critical value, however, Ca2+/PP coacervation within the gelling Ca2+/alginate beads collapses the resulting beads into more compact, interpenetrating polymer networks. Besides their enhanced stability to alkaline environments, these hybrid beads exhibit irregular morphologies with wrinkled and dimpled surface structures and macroscopic (closed) internal pores, and their collapse into these polymer-rich networks also makes them significantly stiffer than their PP-free counterparts. Crucially, these beads also exhibit a much lower solute permeability, which enables highly efficient encapsulation and multiday release of water-soluble small molecules (with the beads encapsulating >90% of the added model payload and sustaining its release over 3-5 d). Collectively, these findings provide a mild and simple (single-step) pathway to generating ionically cross-linked alginate beads with significantly enhanced stability, encapsulation efficiency, and sustained release.

Strategies Employed to Design Biocompatible Metal Nanoparticles for Medical Science and Biotechnology Applications

The applicability of nanomaterials has evolved in biomedical domains thanks to advances in biocompatibility strategies and the mitigation of cytotoxic effects, allowing diagnostics, imaging, and therapeutic approaches. The application of nanoparticles (NP), particularly metal nanoparticles (mNPs), such as gold (Au) and silver (Ag), includes inherent challenges related to the material characteristics, surface modification, and bioconjugation techniques. By tailoring the surface properties through appropriate coating with biocompatible molecules or functionalization with active biomolecules, researchers can reach a harmonious interaction with biological systems or samples (mostly fluids or tissues). Thus, this review highlights the mechanisms associated with the obtention of biocompatible mNP and presents a comprehensive overview of methods that facilitate safe and efficient production. Therefore, we consider this review to be a valuable resource for all researchers navigating this dynamic field.

Poly(allylamine)-tripolyphosphate Ionic Assemblies as Nanocarriers: Friend or Foe?

Designing effective drug nanocarriers that are easy to synthesize, robust, and nontoxic is a significant challenge in nanomedicine. Polyamine-multivalent molecule nanocomplexes are promising drug carriers due to their simple and all-aqueous manufacturing process. However, these systems can present issues of colloidal instability over time and cellular toxicity due to the cationic polymer. In this study, we finely modulate the formation parameters of poly(allylamine-tripolyphosphate) complexes to jointly optimize the robustness and safety. Polyallylamine was ionically assembled with tripolyphosphate anions to form liquid-like nanocomplexes with a size of around 200 nm and a zeta potential of -30 mV. We found that nanocomplexes exhibit tremendous long-term stability (9 months of storage) in colloidal dispersion and that they are suitable as protein-loading agents. Moreover, the formation of nanocomplexes induced by tripolyphosphate anions produces a switch-off in the toxicity of the system by altering the overall charge from positive to negative. In addition, we demonstrate that nanocomplexes can be internalized by bone-marrow-derived macrophage cells. Altogether, these nanocomplexes have attractive and promising properties as delivery nanoplatforms for potential therapies based on the immune system activation.

pH-responsive polyzwitterion covered nanocarriers for DNA delivery

The success of gene therapy relies on gene nanocarriers to achieve therapeutic effects in vivo. Surface shielding of poly(ethylene glycol) (PEG), known as PEGylation, onto gene delivery carriers is a predominant strategy for extending blood circulation and improving therapeutic outcomes in vivo. Nevertheless, PEGylation frequently compromises the transfection efficiency by decreasing the interactions with the cellular membrane of the targeted cells, thereby preventing the cellular uptake and the subsequent endosomal escape. Herein, we developed a stepwise pH-responsive polyplex micelle for the plasmid DNA delivery with the surface covered by ethylenediamine-based polycarboxybetaines. This polyplex micelle switched its surface charge from neutral at pH 7.4 to positive at tumorous and endo-/lysosomal pH (i.e., pH 6.5 and 5.5, respectively), thus enhancing the cellular uptake and facilitating the endosomal escape toward efficient gene transfection. Additionally, the polyplex micelle demonstrated prolonged blood circulation as well as enhanced tumor accumulation, leading to highly effective tumor growth suppression by delivering an antiangiogenic gene. These results suggest the usefulness of a pH-responsive charge-switchable shell polymer on the surface of the polyplex micelle for the efficient nucleic acid delivery.

Synthetic versus Natural Precursor Layer: A Study on the Properties of Biocompatible Chitosan/Carboxymethyl Cellulose Nanofilms

Polyelectrolyte multilayers are nanofilms with vast applications in numerous areas such as medicine and food industry. Recently, they have been getting a lot of attention as potential food coatings for the prevention of fruit decay during transportation and storage, and therefore the coatings need to be biocompatible. In this study, we fabricated thin films made of biocompatible polyelectrolytes, positively charged polysaccharide chitosan, and negatively charged carboxymethyl cellulose on a model silica surface. Typically, to enhance the properties of the prepared nanofilms, the first layer (precursor layer) of poly(ethyleneimine) is used. However, for the construction of completely biocompatible coatings, this could be problematic due to potential toxicity. This study offers an option for a viable candidate as a replacement precursor layer: chitosan itself was adsorbed from a more concentrated solution. In the case of chitosan/carboxymethyl cellulose films, using chitosan over poly(ethyleneimine) as a precursor layer has shown a twofold increase in film thickness, as well as an increase in film roughness. In addition, these properties can be tuned by the presence of a biocompatible background salt (e.g., sodium chloride) in the deposition solution that has proven to change the film thickness and surface roughness depending on the salt concentration. Such a straightforward way of tuning the properties of these films combined with their biocompatibility makes this precursor material a prime candidate for use as a potential food coating.

Therapeutic Delivery of Tumor Suppressor miRNAs for Breast Cancer Treatment

The death rate from breast cancer (BC) has dropped due to early detection and sophisticated therapeutic options, yet drug resistance and relapse remain barriers to effective, systematic treatment. Multiple mechanisms underlying miRNAs appear crucial in practically every aspect of cancer progression, including carcinogenesis, metastasis, and drug resistance, as evidenced by the elucidation of drug resistance. Non-coding RNAs called microRNAs (miRNAs) attach to complementary messenger RNAs and degrade them to inhibit the expression and translation to proteins. Evidence suggests that miRNAs play a vital role in developing numerous diseases, including cancer. They affect genes critical for cellular differentiation, proliferation, apoptosis, and metabolism. Recently studies have demonstrated that miRNAs serve as valuable biomarkers for BC. The contrast in the expression of miRNAs in normal tissue cells and tumors suggest that miRNAs are involved in breast cancer. The important aspect behind cancer etiology is the deregulation of miRNAs that can specifically influence cellular physiology. The main objective of this review is to emphasize the role and therapeutic capacity of tumor suppressor miRNAs in BC and the advancement in the delivery system that can deliver miRNAs specifically to cancerous cells. Various approaches are used to deliver these miRNAs to the cancer cells with the help of carrier molecules, like nanoparticles, poly D, L-lactic-co-glycolic acid (PLGA) particles, PEI polymers, modified extracellular vesicles, dendrimers, and liposomes. Additionally, we discuss advanced strategies of TS miRNA delivery techniques such as viral delivery, self-assembled RNA-triple-helix hydrogel drug delivery systems, and hyaluronic acid/protamine sulfate inter-polyelectrolyte complexes. Subsequently, we discuss challenges and prospects on TS miRNA therapeutic delivery in BC management so that miRNAs will become a routine technique in developing individualized patient profiles.

A critical review on the dissemination of PH and stimuli-responsive polymeric nanoparticular systems to improve drug delivery in cancer therapy

Stimuli-responsive nanocarriers have the potential to revolutionize cancer treatment by allowing precise delivery of drugs to the site of disease. The use of polymeric nanocarriers with surfaces that respond to triggers such as pH, light, temperature, and redox potential enables targeted drug distribution. pH is a particularly useful tool, as the lower pH in tumour microenvironments can trigger changes in drug release. Recent advances in the development of pH-responsive polymer nanoparticles have shown great promise for improved in vivo drug delivery, reduced negative drug responses, and more precise drug distribution. A deeper understanding of these nanocarriers will allow us to overcome the challenges of targeted cancer treatment and create a better drug delivery system.

Nanoparticles of VAV1 siRNA combined with LL37 peptide for the treatment of pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is among the leading causes of cancer-related death, and it is highly resistant to therapy owing to its unique extracellular matrix. VAV1 protein, overexpressed in several cancer diseases including pancreatic cancer (PC), increases tumor proliferation and enhances metastases formation, which are associated with decreased survival. We hypothesized that an additive anti-tumor effect could be obtained by co-encapsulating in PLGA nanoparticles (NPs), the negatively charged siRNA against VAV1 (siVAV1) with the positively charged anti-tumor LL37 peptide, as a counter-ion. Several types of NPs were formulated and were characterized for their physicochemical properties, cellular internalization, and bioactivity in vitro. NPs' biodistribution, toxicity, and bioactivity were examined in a mice PDAC model. An optimal siVAV1 formulation (siVAV1-LL37 NPs) was characterized with desirable physicochemical properties in terms of nano-size, low polydispersity index (PDI), neutral surface charge, high siVAV1 encapsulation efficiency, spherical shape, and long-term shelf-life stability. Cell assays demonstrated rapid engulfment by PC cells, a specific and significant dose-dependent proliferation inhibition, as well as knockdown of VAV1 mRNA levels and migration inhibition in VAV1⁺ cells. Treatment with siVAV1-LL37 NPs in the mice PDAC model revealed marked accumulation of NPs in the liver and in the tumor, resulting in an increased survival rate following suppression of tumor growth and metastases, mediated via the knockdown of both VAV1 mRNA and protein levels. This proof-of-concept study validates our hypothesis of an additive effect in the treatment of PC facilitated by co-encapsulating siVAV1 in NPs with LL37 serving a dual role as a counter ion as well as an anti-tumor agent.

Study on Doxorubicin Loading on Differently Functionalized Iron Oxide Nanoparticles: Implications for Controlled Drug-Delivery Application

Nanoplatforms applied for the loading of anticancer drugs is a cutting-edge approach for drug delivery to tumors and reduction of toxic effects on healthy cells. In this study, we describe the synthesis and compare the sorption properties of four types of potential doxorubicin-carriers, in which iron oxide nanoparticles (IONs) are functionalized with cationic (polyethylenimine, PEI), anionic (polystyrenesulfonate, PSS), and nonionic (dextran) polymers, as well as with porous carbon. The IONs are thoroughly characterized by X-ray diffraction, IR spectroscopy, high resolution TEM (HRTEM), SEM, magnetic susceptibility, and the zeta-potential measurements in the pH range of 3-10. The degree of doxorubicin loading at pH 7.4, as well as the degree of desorption at pH 5.0, distinctive to cancerous tumor environment, are measured. Particles modified with PEI were shown to exhibit the highest loading capacity, while the greatest release at pH 5 (up to 30%) occurs from the surface of magnetite decorated with PSS. Such a slow release of the drug would imply a prolonged tumor-inhibiting action on the affected tissue or organ. Assessment of the toxicity (using Neuro2A cell line) for PEI- and PSS-modified IONs showed no negative effect. In conclusion, the preliminary evaluation of the effects of IONs coated with PSS and PEI on the rate of blood clotting was carried out. The results obtained can be taken into account when developing new drug delivery platforms.

Antibacterial, Adhesive, and Conductive Hydrogel for Diabetic Wound Healing

Diabetic mellitus is one of the leading causes of chronic wounds and remains a challenging issue to be resolved. Herein, a hydrogel with conformal tissue adhesivity, skin-like conductivity, robust mechanical characteristics, as well as active antibacterial function is developed. In this hydrogel, silver nanoparticles decorated polypyrrole nanotubes (AgPPy) and cobalt ions (Co²⁺ ) are introduced into an in situ polymerized poly(acrylic acid) (PAA) and branched poly(ethylenimine) (PEI) network (PPCA hydrogel). The PPCA hydrogel provides active antibacterial function through synergic effects from protonated PEI and AgPPy nanotubes, with a tissue-like mechanical property (≈16.8 ± 4.5 kPa) and skin-like electrical conductivity (≈0.048 S m^-1 ). The tensile and shear adhesive strength (≈15.88 and ≈12.76 kPa, respectively) of the PPCA hydrogel is about two- to threefold better than that of fibrin glue. In vitro studies show the PPCA hydrogel is highly effective against both gram-positive and gram-negative bacteria. In vivo results demonstrate that the PPCA hydrogel promotes diabetic wounds with accelerated healing, with notable inflammatory reduction and prominent angiogenesis regeneration. These results suggest the PPCA hydrogel provide a promising approach to promote diabetic wound healing.

Production of rAAV by plasmid transfection induces antiviral and inflammatory responses in suspension HEK293 cells

Recombinant adeno-associated virus (rAAV) is a clinically proven viral vector for delivery of therapeutic genes to treat rare diseases. Improving rAAV manufacturing productivity and vector quality is necessary to meet clinical and commercial demand. These goals will require an improved understanding of the cellular response to rAAV production, which is poorly defined. We interrogated the kinetic transcriptional response of HEK293 cells to rAAV production following transient plasmid transfection, under manufacturing-relevant conditions, using RNA-seq. Time-series analyses identified a robust cellular response to transfection and rAAV production, with 1,850 transcripts differentially expressed. Gene Ontology analysis determined upregulated pathways, including inflammatory and antiviral responses, with several interferon-stimulated cytokines and chemokines being upregulated at the protein level. Literature-based pathway prediction implicated multiple pathogen pattern sensors and signal transducers in up-regulation of inflammatory and antiviral responses in response to transfection and rAAV replication. Systematic analysis of the cellular transcriptional response to rAAV production indicates that host cells actively sense vector manufacture as an infectious insult. This dataset may therefore illuminate genes and pathways that influence rAAV production, thereby enabling the rational design of next-generation manufacturing platforms to support safe, effective, and affordable AAV-based gene therapies.

Dual Dynamic Covalently Crosslinked Alginate Hydrogels with Tunable Properties and Multiple Stimuli-Responsiveness

Alginate is a biopolymer that can be crosslinked with calcium ions to fabricate cytocompatible hydrogels. However, using calcium ions to crosslink alginate provides limited properties and functions to alginate hydrogels, restricting their biomedical applications. Here, phenylboronic acid-functionalized polyethyleneimine (PBA-PEI) was developed to introduce two orthogonal dynamic covalent crosslinks in the alginate hydrogels, where PBA-PEI was used to crosslink alginate dialdehyde (ADA) through imine bonds and boronate ester bonds. The grafting degree of PBA in the PEI structure was applied to fine-tune the properties of PBA-PEI/ADA hydrogels, including the rheological property, mechanical strength, swelling behavior, and antibacterial activity. In particular, the highly sensitive boronate ester bonds in the network enabled PBA-PEI/ADA hydrogels to be responsive to several stimuli, such as glucose, fructose, and hydrogen peroxide. Taken together, PBA-PEI/ADA hydrogels with tunable properties and multiple stimuli-responsiveness have been demonstrated as smart biomaterials for advanced biomedical applications.

Sustained release of BMP-2 using self-assembled layer-by-layer film-coated implants enhances bone regeneration over burst release

Current clinical products delivering the osteogenic growth factor bone morphogenetic protein 2 (BMP-2) for bone regeneration have been plagued by safety concerns due to a high incidence of off-target effects resulting from bolus release and supraphysiological doses. Layer-by-layer (LbL) film deposition offers the opportunity to coat bone defect-relevant substrates with thin films containing proteins and other therapeutics; however, control of release kinetics is often hampered by interlayer diffusion of drugs throughout the film during assembly, which causes burst drug release. In this work, we present the design of different laponite clay diffusional barrier layer architectures in self-assembled LbL films to modulate the release kinetics of BMP-2 from the surface of a biodegradable implant. Release kinetics were tuned by incorporating laponite in different film arrangements and with varying deposition techniques to achieve release of BMP-2 over 2 days, 4 days, 14 days, and 30 days. Delivery of a low dose (0.5 μg) of BMP-2 over 2 days and 30 days using these LbL film architectures was then compared in an in vivo rat critical size calvarial defect model to determine the effect of BMP-2 release kinetics on bone regeneration. After 6 weeks, sustained release of BMP-2 over 30 days induced 3.7 times higher bone volume and 7.4 times higher bone mineral density as compared with 2-day release of BMP-2, which did not induce more bone growth than the uncoated scaffold control. These findings represent a crucial step in the understanding of how BMP-2 release kinetics influence treatment efficacy and underscore the necessity to optimize protein delivery methods in clinical formulations for bone regeneration. This work could be applied to the delivery of other therapeutic proteins for which careful tuning of the release rate is a key optimization parameter.

siRNA-based nanotherapeutics as emerging modalities for immune-mediated diseases: A preliminary review

Immune‐mediated diseases (IMDs) are chronic conditions that have an immune‐mediated etiology. Clinically, these diseases appear to be unrelated, but pathogenic pathways have been shown to connect them. While inflammation is a common occurrence in the body, it may either stimulate a favorable immune response to protect against harmful signals or cause illness by damaging cells and tissues. Nanomedicine has tremendous promise for regulating inflammation and treating IMIDs. Various nanoparticles coated with nanotherapeutics have been recently fabricated for effective targeted delivery to inflammatory tissues. RNA interference (RNAi) offers a tremendous genetic approach, particularly if traditional treatments are ineffective against IMDs. In cells, several signaling pathways can be suppressed by using RNAi, which blocks the expression of particular messenger RNAs. Using this molecular approach, the undesirable effects of anti‐inflammatory medications can be reduced. Still, there are many problems with using short‐interfering RNAs (siRNAs) to treat IMDs, including poor localization of the siRNAs in target tissues, unstable gene expression, and quick removal from the blood. Nanotherapeutics have been widely used in designing siRNA‐based carriers because of the restricted therapy options for IMIDs. In this review, we have discussed recent trends in the fabrication of siRNA nanodelivery systems, including lipid‐based siRNA nanocarriers, liposomes, and cationic lipids, stable nucleic acid‐lipid particles, polymeric‐based siRNA nanocarriers, polyethylenimine (PEI)‐based nanosystems, chitosan‐based nanoformulations, inorganic material‐based siRNA nanocarriers, and hybrid‐based delivery systems. We have also introduced novel siRNA‐based nanocarriers to control IMIDs, such as pulmonary inflammation, psoriasis, inflammatory bowel disease, ulcerative colitis, rheumatoid arthritis, etc. This study will pave the way for new avenues of research into the diagnosis and treatment of IMDs.

Cytostatic Effects of Polyethyleneimine Surfaces on the Mesenchymal Stromal Cell Cycle

Polyelectrolytes assembled layer-by-layer (PEMs) are commonly used as functional coatings to build-up biological interfaces, particularly suitable as compatible layers for the interaction with a biological medium, providing suitable conditions to promote or prevent cell seeding while maintaining the phenotype. The proper assessment of the biocompatibility of PEMs and the elucidation of the related mechanisms are therefore of paramount importance. In this study, we report in detail the effect of two different PEM endings, polystyrene sulfonate (PSS) and polyethylenimine (PEI), respectively, on the cell adhesion, growth, and viability of human bone mesenchymal stromal cells (MSCs). The results have shown that PSS-ended substrates appear to be the most suitable to drive the cell adhesion and phenotype maintenance of MSCs, showing good biocompatibility. On the contrary, while the cells seem to adhere more quickly and strongly on the PEI-ended surfaces, the interaction with PEI significantly affects the growth and viability, reducing the cell spreading capability, by sequestering the adhesion molecules already in the very early steps of cell–substrate contact. These results point to the promotion of a cytostatic effect of PEI, rather than the often-claimed cytotoxicity.

Polyethylenimine-Coated Ultrasmall Holmium Oxide Nanoparticles: Synthesis, Characterization, Cytotoxicities, and Water Proton Spin Relaxivities

Water proton spin relaxivities, colloidal stability, and biocompatibility of nanoparticle magnetic resonance imaging (MRI) contrast agents depend on surface-coating ligands. In this study, hydrophilic and biocompatible polyethylenimines (PEIs) of different sizes (M_n = 1200 and 60,000 amu) were used as surface-coating ligands for ultrasmall holmium oxide (Ho₂O₃) nanoparticles. The synthesized PEI1200- and PEI60000-coated ultrasmall Ho₂O₃ nanoparticles, with an average particle diameter of 2.05 and 1.90 nm, respectively, demonstrated low cellular cytotoxicities, good colloidal stability, and appreciable transverse water proton spin relaxivities (r₂) of 13.1 and 9.9 s⁻¹mM⁻¹, respectively, in a 3.0 T MR field with negligible longitudinal water proton spin relaxivities (r₁) (i.e., 0.1 s⁻¹mM⁻¹) for both samples. Consequently, for both samples, the dose-dependent contrast changes in the longitudinal (R₁) and transverse (R₂) relaxation rate map images were negligible and appreciable, respectively, indicating their potential as efficient transverse T₂ MRI contrast agents in vitro.

Modification of Lipid-Based Nanoparticles: An Efficient Delivery System for Nucleic Acid-Based Immunotherapy

Lipid-based nanoparticles (LBNPs) are biocompatible and biodegradable vesicles that are considered to be one of the most efficient drug delivery platforms. Due to the prominent advantages, such as long circulation time, slow drug release, reduced toxicity, high transfection efficiency, and endosomal escape capacity, such synthetic nanoparticles have been widely used for carrying genetic therapeutics, particularly nucleic acids that can be applied in the treatment for various diseases, including congenital diseases, cancers, virus infections, and chronic inflammations. Despite great merits and multiple successful applications, many extracellular and intracellular barriers remain and greatly impair delivery efficacy and therapeutic outcomes. As such, the current state of knowledge and pitfalls regarding the gene delivery and construction of LBNPs will be initially summarized. In order to develop a new generation of LBNPs for improved delivery profiles and therapeutic effects, the modification strategies of LBNPs will be reviewed. On the basis of these developed modifications, the performance of LBNPs as therapeutic nanoplatforms have been greatly improved and extensively applied in immunotherapies, including infectious diseases and cancers. However, the therapeutic applications of LBNPs systems are still limited due to the undesirable endosomal escape, potential aggregation, and the inefficient encapsulation of therapeutics. Herein, we will review and discuss recent advances and remaining challenges in the development of LBNPs for nucleic acid-based immunotherapy.

Nonviral Delivery Systems of mRNA Vaccines for Cancer Gene Therapy

In recent years, the use of messenger RNA (mRNA) in the fields of gene therapy, immunotherapy, and stem cell biomedicine has received extensive attention. With the development of scientific technology, mRNA applications for tumor treatment have matured. Since the SARS-CoV-2 infection outbreak in 2019, the development of engineered mRNA and mRNA vaccines has accelerated rapidly. mRNA is easy to produce, scalable, modifiable, and not integrated into the host genome, showing tremendous potential for cancer gene therapy and immunotherapy when used in combination with traditional strategies. The core mechanism of mRNA therapy is vehicle-based delivery of in vitro transcribed mRNA (IVT mRNA), which is large, negatively charged, and easily degradable, into the cytoplasm and subsequent expression of the corresponding proteins. However, effectively delivering mRNA into cells and successfully activating the immune response are the keys to the clinical transformation of mRNA therapy. In this review, we focus on nonviral nanodelivery systems of mRNA vaccines used for cancer gene therapy and immunotherapy.

New insight into the structural changes of apoferritin pores in the process of doxorubicin loading at an acidic pH: Molecular dynamics simulations

Apoferritin (APO-Fr) is one of the most investigated proteins proposed as an advanced structure for drug delivery systems. Herein, molecular dynamics simulation was employed to compare the opening of 3-fold and 4-fold pores in APO-Fr during the partial disassembly process at an acidic pH. We showed that more hydrophilic residues in the surface of 3-fold pores compared to 4-fold pores facilitate increased flexibility and a higher tendency to open. In particular, dissociation is induced by the presence of Doxorubicin (DOX) close to 3-fold pores. Our simulations showed loaded DOXs on the APO-Fr surface were mainly involved in the hydrogen bond interactions with the hydrophilic residues, suggesting the difficulty of hydrophobic drugs loading in APO-Fr with the partial disassembly process. However, π-π interactions as well as hydrogen bonds between protein and DOXs were mediated by the basic and acidic amino acids such as HIP128, GLU17, and LYS143 at the open pores, providing penetration of DOXs into the H-Apo-Fr. We conclude that increased drug encapsulations and loading capacity of hydrophobic drugs into the cavity of APO-Fr are feasible by further disassembly of openings to access the internal hydrophobic portions of the protein.

Amine-Rich Coatings to Potentially Promote Cell Adhesion, Proliferation and Differentiation, and Reduce Microbial Colonization: Strategies for Generation and Characterization

Biomaterial surface modification represents an important approach to obtain a better integration of the material in surrounding tissues. Different techniques are focused on improving cell support as well as avoiding efficiently the development of infections, such as by modifying the biomaterial surface with amine groups (–NH2). Previous studies showed that –NH2 groups could promote cell adhesion and proliferation. Moreover, these chemical functionalities may be used to facilitate the attachment of molecules such as proteins or to endow antimicrobial properties. This mini-review gives an overview of different techniques which have been used to obtain amine-rich coatings such as plasma methods and adsorption of biomolecules. In fact, different plasma treatment methods are commonly used with ammonia gas or by polymerization of precursors such as allylamine, as well as coatings of proteins (for example, collagen) or polymers containing –NH2 groups (for example, polyethyleneimine). Moreover, this mini-review will present the methods used to characterize such coatings and, in particular, quantify the –NH2 groups present on the surface by using dyes or chemical derivatization methods.

Polyethylenimine-Bisphosphonate-Cyclodextrin Ternary Conjugates: Supramolecular Systems for the Delivery of Antineoplastic Drugs

Bisphosphonates (BPs) are bone-binding molecules that provide targeting capabilities to bone cancer cells when conjugated with drug-carrying polymers. This work reports the design, synthesis, and biological evaluation of polyethyleneimine-BP-cyclodextrin (PEI-BP-CD) ternary conjugates with supramolecular capabilities for the loading of antineoplastic drugs. A straightforward, modular, and versatile strategy based on the click aza-Michael addition reaction of vinyl sulfones (VSs) allows the grafting of BPs targeting ligands and βCD carrier appendages to the PEI polymeric scaffold. The in vitro evaluation (cytotoxicity, cellular uptake, internalization routes, and subcellular distribution) for the ternary conjugates and their doxorubicin inclusion complexes in different bone-related cancer cell lines (MC3T3-E1 osteoblasts, MG-63 sarcoma cells, and MDA-MB-231 breast cancer cells) confirmed specificity, mitochondrial targeting, and overall capability to mediate a targeted drug transport to those cells. The in vivo evaluation using xenografts of MG-63 and MDA-MB-231 cells on mice also confirmed the targeting of the conjugates.

Multifunctional Immunoadjuvants for Use in Minimalist Nucleic Acid Vaccines

Subunit vaccines based on antigen-encoding nucleic acids have shown great promise for antigen-specific immunization against cancer and infectious diseases. Vaccines require immunostimulatory adjuvants to activate the innate immune system and trigger specific adaptive immune responses. However, the incorporation of immunoadjuvants into nonviral nucleic acid delivery systems often results in fairly complex structures that are difficult to mass-produce and characterize. In recent years, minimalist approaches have emerged to reduce the number of components used in vaccines. In these approaches, delivery materials, such as lipids and polymers, and/or pDNA/mRNA are designed to simultaneously possess several functionalities of immunostimulatory adjuvants. Such multifunctional immunoadjuvants encode antigens, encapsulate nucleic acids, and control their pharmacokinetic or cellular fate. Herein, we review a diverse class of multifunctional immunoadjuvants in nucleic acid subunit vaccines and provide a detailed description of their mechanisms of adjuvanticity and induction of specific immune responses.

Co-encapsulation of collagenase type I and silibinin in chondroitin sulfate coated multilayered nanoparticles for targeted treatment of liver fibrosis

Components of the extracellular matrix (ECM) are overexpressed in fibrotic liver. Collagen is the main component of the liver fibrosis stroma. Here we demonstrate that chondroitin sulfate coated multilayered 50-nm nanoparticles encapsulating collagenase and silibinin (COL + SLB-MLPs) break down the dense collagen stroma, while silibinin inhibits activated hepatic stellate cells. The nanoparticles were taken up to a much greater extent by hepatic stellate cells than by normal hepatocytes, and they down-regulated production of type I collagen. In addition, chondroitin sulfate protected the collagenase from premature deactivation. COL + SLB-MLPs were delivered to the cirrhotic liver, and the collagenase and silibinin synergistically inhibited fibrosis in mice. Immunofluorescence staining of liver tissues revealed that CD44, mediated by chondroitin sulfate, delivered the nanoparticles to hepatic stellate cells. This strategy holds promise for degrading extracellular stroma and thereby facilitating drug penetration into fibrotic liver and related diseases such as liver cirrhosis and liver cancer.

Synthesis and Characterization of Click Nucleic Acid Conjugated Polymeric Microparticles for DNA Delivery Applications

Microparticle-mediated nucleic acid delivery is a popular strategy to achieve therapeutic outcomes via antisense gene therapy. However, current methods used to fabricate polymeric microparticles suffer from suboptimal properties such as particle polydispersity and low encapsulation efficiency. Here, a new particulate delivery system based on step-growth thiol-Michael dispersion polymerization is reported in which a low polydispersity microparticle is functionalized with a synthetic nucleic acid mimic, namely, click nucleic acids (CNA). CNA oligomers, exhibiting an average length of approximately four nucleic acid repeat units per chain for both adenine and thymine bases, were successfully conjugated to excess thiols present in the microparticles. Effective DNA loading was obtained by simple mixing, and up to 6 ± 2 pmol of complementary DNA/mg of particle was achieved, depending on the length of DNA used. In addition, DNA loading was orders of magnitude less for noncomplementary sequences and sequences containing an alternating base mismatch. The DNA release properties were evaluated, and it was found that release could be triggered by sudden changes in temperature but was unaffected over a range of pH. Finally, phagocytosis of loaded microparticles was observed by confocal microscopy and corroborated by an increase in cellular metabolic activity up to 90%. Overall, this work suggests that CNA functionalized microparticles could be a promising platform for controlled DNA delivery.

Doxorubicin Loaded PLGA Nanoparticle with Cationic/Anionic Polyelectrolyte Decoration: Characterization, and Its Therapeutic Potency

Optimized Doxorubicin hydrochloride (DOX) loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (DPN) were prepared by controlling the water/oil distribution of DOX at different pH solutions and controlling the electrostatic interaction between DOX and different terminated-end PLGAs. Furthermore, cationic polyethylenimine (PEI) and anionic poly (acrylic acid) (PAA) were alternately deposited on DPN surface to form PEI-DPN (IDPN) and PAA-PEI-DPN (AIDPN) to enhance cancer therapy potency. Compared to DPN, IDPN exhibited a slower release rate in physiological conditions but PEI was demonstrated to increase the efficiency of cellular uptake and endo/lysosomal escape ability. AIDPN, with the outermost negatively charged PAA layer, still retained better endo/lysosomal escape ability compared to DPN. In addition, AIDPN exhibited the best pH-dependent release profile with 1.6 times higher drug release in pH 5.5 than in pH 7.4. Therefore, AIDPN with the characteristics of PEI and PAA simultaneously was the most optional cancer therapy choice within these three PLGA nanoparticles. As the proposed nanoparticles integrated optimal procedure factors, and possessed cationic and anionic outlayer, our drug delivery nanoparticles can provide an alternative solution to current drug delivery technologies.

Methods for the Assembly and Characterization of Polyelectrolyte Multilayers as Microenvironments to Modulate Human Mesenchymal Stromal Cell Response

Thin films are of interest in materials design because they allow for the modification of surface properties of materials while the bulk properties of the material are largely unaffected. In this work, we outline methods for the assembly of thin films using a technique known as layer-by-layer (LbL). Furthermore, their interactions with human mesenchymal stromal cells (hMSCs) are discussed. hMSCs are a subject of growing interest because of their potential to treat or cure diseases, given their immunosuppressive properties, multipotent differentiation capabilities, and tissue regeneration capabilities. Numerous improvements and modifications have been suggested for the harvesting, treatment, and culture of hMSCs prior to their administration in human subjects. Here, we discuss methods to assess the interactions of hMSCs with thin LbL-assembled films of heparin and collagen. Three different methods are discussed. The first details the preparation of heparin/collagen multilayers on different surfaces and the seeding of cells on these multilayers. The second method details the characterization of multilayers, including techniques to assess the thickness, roughness, and surface charge of the multilayers, as well as in situ deposition of multilayers. The third method details the analysis of cell interactions with the multilayers, including techniques to assess proliferation, viability, real-time monitoring of hMSC behavior, analysis of hMSC-adhesive proteins on the multilayers, immunomodulatory factor expression of hMSCs, and cytokine expression on heparin/collagen multilayers. We propose that the methods described in this work will assist in the design and characterization of LbL-assembled thin films and the analysis of hMSCs cultured on these thin films.

Enhancement of Intracellular Calcium Ion Mobilization by Moderately but Not Highly Positive Material Surface Charges

Electrostatic forces at the cell interface affect the nature of cell adhesion and function; but there is still limited knowledge about the impact of positive or negative surface charges on cell-material interactions in regenerative medicine. Titanium surfaces with a variety of zeta potentials between −90 mV and +50 mV were generated by functionalizing them with amino polymers, extracellular matrix proteins/peptide motifs and polyelectrolyte multilayers. A significant enhancement of intracellular calcium mobilization was achieved on surfaces with a moderately positive (+1 to +10 mV) compared with a negative zeta potential (−90 to −3 mV). Dramatic losses of cell activity (membrane integrity, viability, proliferation, calcium mobilization) were observed on surfaces with a highly positive zeta potential (+50 mV). This systematic study indicates that cells do not prefer positive charges in general, merely moderately positive ones. The cell behavior of MG-63s could be correlated with the materials’ zeta potential; but not with water contact angle or surface free energy. Our findings present new insights and provide an essential knowledge for future applications in dental and orthopedic surgery.

Reduction of inflammation in a chronic periodontitis model in rats by TNF-α gene silencing with a topically applied siRNA-loaded calcium phosphate paste

We developed a calcium phosphate-based paste containing siRNA against TNF-α and investigated its anti-inflammatory and bone-healing effects in vitro and in vivo in a rat periodontitis model. The bioactive spherical CaP/PEI/siRNA/SiO₂ nanoparticles had a core diameter of 40-90 nm and a positive charge (+23 mV) that facilitated cellular uptake. The TNF- α gene silencing efficiency of the nanoparticles in J774.2 monocytes, gingival-derived cells, and bone marrow-derived cells was 12 ± 2%, 36 ± 8%, and 35 ± 22%, respectively. CaP/PEI/siRNA/SiO₂ nanoparticles cancelled the suppression of alkaline phosphatase (ALP) activity in LPS-stimulated bone marrow-derived cells. In vivo, ALP mRNA was up-regulated, TNF-α mRNA was down-regulated, and the amount of released TNF-α was significantly reduced after topical application of the calcium phosphate-based paste containing siRNA-loaded nanoparticles. The number of TNF-α-positive cells in response to CaP/PEI/siRNA/SiO₂ nanoparticle application was lower than that observed in the absence of siRNA. Elevated ALP activity and numerous TRAP-positive cells (osteoclasts) were observed in response to the application of all calcium phosphate pastes. These results demonstrate that local application of a paste consisting of siRNA-loaded calcium phosphate nanoparticles successfully induces TNF-α silencing in vitro and in vivo and removes the suppression of ALP activity stimulated by inflammation. STATEMENT OF SIGNIFICANCE: We developed a calcium phosphate-based paste containing nanoparticles loaded with siRNA against TNF-α. The nanoparticles had a core diameter of 40-90 nm and positive charge (+23 mV). The anti-inflammatory and osteoinductive effects of the paste were investigated in vitro and in vivo in a rat periodontitis model. In vitro, the TNF-α gene silencing efficiency of the nanoparticles in J774.2 monocytes, gingival-derived cells, and bone marrow-derived cells was 12 ± 2%, 36 ± 8%, and 35 ± 22%, respectively. The ALP activity of bone marrow-derived cells was recovered. In vivo, TNF-α mRNA was down-regulated and the amount of released TNF-α was significantly reduced, whereas the ALP mRNA was up-regulated. Elevated ALP activity and TRAP-positive cells were observed by immunohistochemistry.

Immobilization of poly(lactide-co-glycolide) microspheres on bone implant materials for antibiotic release and the binding mechanisms

Bone implants are susceptible to postoperative infections. Immobilization of antibiotic-loaded microparticles on implants is an effective approach to addressing this problem. Immobilization methods reported in earlier studies frequently used special or potentially harmful conditions. Therefore, the present study explored a new method to immobilize poly(lactide-co-glycolide) (PLGA) microspheres on bone implant materials. PLGA microspheres were prepared by an emulsion method using polyvinyl alcohol (PVA) as an emulsifier. The microspheres were immobilized on two commonly used orthopaedic biomaterials [hydroxyapatite-coated titanium (HA-Ti) and poly(methyl methacrylate) (PMMA)] by dispersing on the surface followed by vacuum drying. Microspheres were retained stably on both materials even after immersion in phosphate-buffered saline for 12 d. Pretreatment of microspheres with sodium borate (i.e., an eliminator of hydroxyl groups of PVA) substantially reduced their retention on HA-Ti, but only moderately reduced their retention on PMMA. This suggested that the binding of the residual PVA on the microspheres to the HA coating is the dominant contributor to their immobilization on HA-Ti, whereas other forces contributed substantially to their immobilization on PMMA. Microspheres containing ciprofloxacin (a water-soluble antibiotic) and triclosan (an oil-soluble antibiotic) were immobilized on HA-Ti and PMMA, respectively. They effectively killed adjacent bacteria. These results offer a simple and versatile method for immobilizing drug-release microspheres on some important bone implant surfaces.

Growing Patterned, Cross-linked Nanoscale Polymer Films from Organic and Inorganic Surfaces Using Ring-Opening Metathesis Polymerization

The ability to modify substrates with thin polymer films allows for the tailoring of surface properties, and through combination of patterning finds use in a large variety of applications such as electronics and lab-on-chip devices. Although many techniques can be used to afford polymer-modified surfaces such as surface-initiated polymerization or layer-by-layer methodologies, their stability in a wide range of environments as well as their ability to target specific chemistry are critical factors to enable their successful application. In this paper, we report a facile technique in creating nanoscale polymer thin films using solid-state continuous assembly of polymers via ring-opening metathesis polymerization (ssCAP_ROMP) directly from surfaces functionalized through silanization. Using a polymeric precursor that includes norbornene moieties, a highly dense cross-linked network of polymer can be grown in a bottom-up fashion to afford thin films from an olefin-terminated silanized planar surface. Such nanotechnology affords films retaining the desirable qualities of previously reported methods while, at the same time, being covalently bound to the substrate: they are virtually pinhole free and can be reinitiated multiple times. By combining this process with microcontact printing, patterned films can be created by either the patterned deposition of a catalyst or by controlling the surface silanization chemistry and placement of olefin-terminated and nonreactive silanes. Additionally, patterned ssCAP_ROMP films were grown from SU-8 by selectively functionalizing the surface through masking and lift-off processes after the silanization step, thereby spatially controlling the surface-initiation, and subsequent polymer film formation. These patterned films expand the capabilities of the CAP_ROMP process and offer advantages over other film formation techniques in processes where patterned substrates and modified but robust surface chemistries are utilized.

BIOPHYSICS MEETS GENE THERAPY: HOW EXPLORING SUPERCOILING-DEPENDENT STRUCTURAL CHANGES IN DNA LED TO THE DEVELOPMENT OF MINIVECTOR DNA

Supercoiling affects every aspect of DNA function (replication, transcription, repair, recombination, etc.), yet the vast majority of studies on DNA and crystal structures of the molecule utilize short linear duplex DNA, which cannot be supercoiled. To study how supercoiling drives DNA biology, we developed and patented methods to make milligram quantities of tiny supercoiled circles of DNA called minicircles. We used a collaborative and multidisciplinary approach, including computational simulations (both atomistic and coarse-grained), biochemical experimentation, and biophysical methods to study these minicircles. By determining the three-dimensional conformations of individual supercoiled DNA minicircles, we revealed the structural diversity of supercoiled DNA and its highly dynamic nature. We uncovered profound structural changes, including sequence-specific base-flipping (where the DNA base flips out into the solvent), bending, and denaturing in negatively supercoiled minicircles. Counterintuitively, exposed DNA bases emerged in the positively supercoiled minicircles, which may result from inside-out DNA (Pauling-like, or "P-DNA"). These structural changes strongly influence how enzymes interact with or act on DNA. We hypothesized that, because of their small size and lack of bacterial sequences, these small supercoiled DNA circles may be efficient at delivering DNA into cells for gene therapy applications. "Minivectors," as we named them for this application, have proven to have therapeutic potential. We discovered that minivectors efficiently transfect a wide range of cell types, including many clinically important cell lines that are refractory to transfection with conventional plasmid vectors. Minivectors can be aerosolized for delivery to lungs and transfect human cells in culture to express RNA or genes. Importantly, minivectors demonstrate no obvious vector-associated toxicity. Minivectors can be repeatedly delivered and are long-lasting without integrating into the genome. Requests from colleagues around the world for minicircle and minivector DNA revealed a demand for our invention. We successfully obtained start-up funding for Twister Biotech, Inc. to help fulfill this demand, providing DNA for those who needed it, with a long-term goal of developing human therapeutics. In summary, what started as a tool for studying DNA structure has taken us in new and unanticipated directions.

A facile way for development of three-dimensional localized drug delivery system for bone tissue engineering

Removing malignant bone tumors results in critical size bone defects. These voids in bones should be filled by a proper scaffold that not only can support cell ingrowth and bone regeneration but also it has to show a desirable ability in long-term releasing anticancer drugs in order to prevent the growth of remaining cancer cells. Applying this scaffold can significantly improve the outcome of bone tumors treatment. In this study, a novel way is proposed for immobilization of doxorubicin (DOX)-loaded polycaproloactone (PCL) microparticles on the hardystonite (HT) scaffold surfaces. High interconnected porous HT scaffolds with immobilized DOX-encapsulated PCL microparticles can be successfully fabricated by modified water/oil/water method. In the present work, we verify a slow release of DOX over 30 days from PCL microparticles inside HT scaffold. Our developed HT scaffolds with the long-term release of DOX are more effective in reduction of Saos-2 cancer cells viability and induce higher degrees of apoptosis compared to DOX dip coated HT scaffolds. Encapsulating DOX into PCL microparticles significantly improves the anti-tumor activity of DOX by regulating the expression of apoptosis-related genes. Our results suggest that by immobilization of polymeric vehicles on the ceramic scaffold for controlled drug release, we can achieve high efficiency in apoptosis of cancer cells.

Hyaluronic Acid Nanoparticle Composite Films Confer Favorable Time-Dependent Biofunctions for Vascular Wound Healing

Vascular stent implantation is the primary treatment for coronary artery disease. Surface modification of coronary stents is a topic of interest to prevent thrombosis and restenosis and to promote endothelization. However, bioactive coatings on implants have not yet been fully developed for the time-ordered biological requirements of vascular stents. The first month after vascular stent implantation, the pathological changes in the injured vascular tissue are complex and time-ordered. Therefore, vascular stents possess time-dependent biofunctions with early phase anticoagulant and anti-inflammatory properties. In the later stage, inhibitory effects on smooth muscle cell proliferation and the promotion of endothelial cell adhesion might meet the requirements of vascular repair. We fabricated three types of hyaluronic acid nanoparticles (HA-NPs) by subjecting HA and poly(ether imide) to ethyl(dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide coupling reaction. The HA-NPs prepared by HA with a molecular weight of 100 kDa showed the best stability in a hyaluronidase environment. HA-NP composite films (HA-NCFs) were then fabricated by coimmobilizing selected HA-NPs (100 kDa) and HA molecules (100 kDa) through amide reaction on PDA/HD coated 316 L stainless steel surfaces. The detachment behavior of HA-NPs (100 kDa) in PBS for 20 days indicated that the HA-NPs (100 kDa) gradually detached from the surface. In vitro tests (anticoagulant and anti-inflammatory tests, endothelial cells, and smooth muscle cells seeding, and bacterial adhesion test) indicated that the newly fabricated HA-NCFs have inhibitory effects on the adhesion of fibrinogen, platelets, macrophages, bacteria, SMCs, and ECs. As the HA-NPs detached from the surface, the HA-NCFs showed excellent gradual comprehensive biocompatibility, which promoted adhesion and proliferation of ECs while still exerting inhibitory effects on the platelets, macrophages, and SMCs. Finally, in vivo SS wire implantation test (aortic implantation in healthy Sprague-Dawley rats) showed that HA-NCFs possessed anti-inflammatory properties, inhibited the proliferation of smooth muscle cells, and promoted re-endothelialization. In particular, HA-NCFs with time-dependent biofunctions showed better antirestenosis effects than those of surfaces modified with molecular HA, which exhibited constant biocompatibility. This study provides an important basis for the construction of HA-NP composite films with favorable time-dependent biofunctions for the time-ordered biological requirements of vascular stent.

A biofunctionalized viral delivery patch for spatially defined transfection

Gene therapy holds the significance of correcting genetic defects. However, difficulties in the in vivo delivery to the targeted tissues and systemic delivery remain the biggest challenges to be overcome. Here, a robust system of biofunctionalized polymeric layer-mediated lentiviral delivery was designed for the site-specific spatial and temporal control of viral gene delivery. Poly glycidyl methacrylate (pGMA) modification of a substrate via initiated chemical vapor deposition (iCVD) followed by polyethyleneimine (PEI) immobilization provided the adhesion site for the lentivirus. Furthermore, the polymeric patch based gene delivery system showed a high rate of gene transduction compared to bolus treatment. Furthermore, by using mask patterning, we were able to spatially pattern the lentivirus which allowed spatially defined transfection.

A polyethylenimine-based diazeniumdiolate nitric oxide donor accelerates wound healing

A polyethylenimine based diazeniumdiolate nitric oxide donor was prepared to accelerate wound healing.

Redox-sensitive, PEG-shielded carboxymethyl PEI nanogels silencing MicroRNA-21, sensitizes resistant ovarian cancer cells to cisplatin

A series of branched polyethylenimine (PEI) modifications including PEGylation (PEG2k-PEI) for steric shielding, redox-sensitive crosslinking for synthesis PEG2k-PEI-ss nanogels and subsequent carboxymethylation (PEG2k-CMPEI-ss) for modulation of the polymer pk_a have been introduced for cellular delivery of Anti-miR-21. The synthesis was characterized using ¹H NMR, FTIR, TNBS, potentiometric titration, particle size and ζ potential. Loading of Anti-miR-21 at various N/P ratios was investigated by gel retardation, ethidium bromide dye exclusion, heparin sulfate competition and DNase I digestion experiments. The miR-21 silencing was measured by stem-loop RT PCR in A2780 ovarian cancer cell lines whether it is sensitive to resistant to cisplatin. It has been shown that PEG2k-CMPEI-ss was well suited for delivery of Anti-miR-21 in terms of nucleic acid loading, preservation against extracellular matrix and nucleases and sequence-specific silencing of miRNA-21 in vitro. Moreover, it has been demonstrated that pre-treating cells with Anti-miR-21 loaded nanogels can sensitize them to cis-Pt even at non-toxic concentraions. The results indicate that PEG2k-CMPEI-ss mediated microRNA delivery can be considered as a novel strategy for ovarian cancer therapy.

Biocompatible Coatings from Smart Biopolymer Nanoparticles for Enzymatically Induced Drug Release

Nanoparticles can be used as a smart drug delivery system, when they release the drug only upon degradation by specific enzymes. A method to create such responsive materials is the formation of hydrogel nanoparticles, which have enzymatically degradable crosslinkers. Such hydrogel nanoparticles were prepared by ionotropic gelation sodium alginate with lysine-rich peptide sequences-either α-poly-L-lysine (PLL) or the aggrecanase-labile sequence KKKK-GRD-ARGSV↓NITEGE-DRG-KKKK. The nanoparticle suspensions obtained were analyzed by means of dynamic light scattering and nanoparticle tracking analysis. Degradation experiments carried out with the nanoparticles in suspension revealed enzyme-induced lability. Drugs present in the polymer solution during the ionotropic gelation can be encapsulated in the nanoparticles. Drug loading was investigated for interferon-β (IFN-β) as a model, using a bioluminescence assay with MX2Luc2 cells. The encapsulation efficiency for IFN-β was found to be approximately 25%. The nanoparticles suspension can be used to spray-coat titanium alloys (Ti-6Al-4V) as a common implant material. The coatings were proven by ellipsometry, reflection-absorption infrared spectroscopy, and X-ray photoelectron spectroscopy. An enzyme-responsive decrease in layer thickness is observed due to the degradation of the coatings. The Alg/peptide coatings were cytocompatible for human gingival fibroblasts (HGFIB), which was investigated by CellTiterBlue and lactate dehydrogenase (LDH) assay. However, HGFIBs showed poor adhesion and proliferation on the Alg/peptide coatings, but these could be improved by modification of the alginate with a RGD-peptide sequence. The smart drug release system presented can be further tailored to have the right release kinetics and cell adhesion properties.

Layer-by-layer DNA films incorporating highly transfecting bioreducible poly(amido amine) and polyethylenimine for sequential gene delivery

Background

The layer-by-layer (LbL) assembly method offers a molecular level control of the amount and spatial distribution of bioactive molecules. However, successful clinical translation of LbL film technology will most certainly require a better understanding and control of not only the film assembly process, but also film disassembly kinetics in physiologic conditions.

Purpose

This work focuses on the understanding and control of degradation properties of LbL films for localized gene delivery.

Methods

Bioreducible poly(amido amine)s (PAAs) containing cystaminebisacrylamide (CBA), methylenebisacrylamide, and 5-amino-1-pentanol (APOL) were synthesized by Michael addition polymerization for the construction of bioreducible LbL films capable of sequential gene delivery.

Results

The synthesized PAAs were screened for desirable buffering capacity, cell transfection, and cytotoxicity characteristics together with 25 kDa branched polyethylenimine (PEI) and cross-linked 800 Da PEI. By screening the various polycations we were able to identify a copolymer of CBA and APOL for the subsequent construction of the LbL films. By incorporating a highly transfecting polycation and a nondiffusing polycation we were able to improve the overall transfection of HEK293 and MC3T3 cells from the bioreducible LbL films. We also demonstrated the dual-stage release and transfection of two different DNAs from the LbL films.

Conclusion

The results indicate that LbL films consisting of bioreducible PAAs and non-diffusing polyelectrolytes have excellent degradation properties for the development of LbL coating technology for localized gene delivery applications.

Surface-Modified Shortwave-Infrared-Emitting Nanophotonic Reporters for Gene-Therapy Applications

Gene therapy is emerging as the next generation of therapeutic modality with United States Food and Drug Administration approved gene-engineered therapy for cancer and a rare eye-related disorder, but the challenge of real-time monitoring of on-target therapy response remains. In this study, we have designed a theranostic nanoparticle composed of shortwave-infrared-emitting rare-earth-doped nanoparticles (RENPs) capable of delivering genetic cargo and of real-time response monitoring. We showed that the cationic coating of RENPs with branched polyethylenimine (PEI) does not have a significant impact on cellular toxicity, which can be further reduced by selectively modifying the surface characteristics of the PEI coating using counter-ions and expanding their potential applications in photothermal therapy. We showed the tolerability and clearance of a bolus dose of RENPs@PEI in mice up to 7 days after particle injection in addition to the RENPs@PEI ability to distinctively discern lung tumor lesions in a breast cancer mouse model with an excellent signal-to-noise ratio. We also showed the availability of amine functional groups in the collapsed PEI chain conformation on RENPs, which facilitates the loading of genetic cargo that hybridizes with target gene in an in vitro cancer model. The real-time monitoring and delivery of gene therapy at on-target sites will enable the success of an increased number of gene- and cell-therapy products in clinical trials.

Delivery of the improved BMP-2-Advanced plasmid DNA within a gene-activated scaffold accelerates mesenchymal stem cell osteogenesis and critical size defect repair

Gene-activated scaffolds have been shown to induce controlled, sustained release of functional transgene both in vitro and in vivo. Bone morphogenetic proteins (BMPs) are potent mediators of osteogenesis however we found that the delivery of plasmid BMP-2 (pBMP-2) alone was not sufficient to enhance bone formation. Therefore, the aim of this study was to assess if the use of a series of modified BMP-2 plasmids could enhance the functionality of a pBMP-2 gene-activated scaffold and ultimately improve bone regeneration when implanted into a critical sized bone defect in vivo. A multi-cistronic plasmid encoding both BMP-2 and BMP-7 (BMP-2/7) was employed as was a BMP-2-Advanced plasmid containing a highly truncated intron sequence. With both plasmids, the highly efficient cytomegalovirus (CMV) promoter sequence was used. However, as there have been reports that the elongated factor 1-α promoter is more efficient, particularly in stem cells, a BMP-2-Advanced plasmid containing the EF1α promoter was also tested. Chitosan nanoparticles (CS) were used to deliver each plasmid to MSCs and induced transient up-regulation of BMP-2 protein expression, in turn significantly enhancing MSC-mediated osteogenesis when compared to untreated controls (p < 0.001). When incorporated into a bone mimicking collagen-hydroxyapatite scaffold, the BMP-2-Advanced plasmid, under the control of the CMV promotor, induced MSCs to produce approximately 2500 μg of calcium per scaffold, significantly higher (p < 0.001) than all other groups. Just 4 weeks post-implantation in vivo, this cell-free gene-activated scaffold induced significantly more bone tissue formation compared to a pBMP-2 gene-activated scaffold (p < 0.001) as indicated by microCT and histomorphometry. Immunohistochemistry revealed that the BMP-2-Advanced plasmid accelerated differentiation of osteoprogenitor cells to mature osteoblasts, thus causing rapid healing of the bone defects. This study confirms that optimising the plasmid construct can enhance the functionality of gene-activated scaffolds and translate to accelerated bone formation in a critical sized defect.

Poly-L-ornithine/fucoidan-coated calcium carbonate microparticles by layer-by-layer self-assembly technique for cancer theranostics

Recently, the layer-by-layer (LbL) self-assembly technology has attracted the enormous interest of researchers in synthesizing various pharmaceutical dosage forms. Herewith, we designed a biocompatible drug delivery system containing the calcium carbonate microparticles (CaCO₃ MPs) that coated with the alternatively charged polyelectrolytes, i.e., poly-L-ornithine (PLO)/fucoidan by LbL self-assembly process (LbL MPs). Upon coating with the polyelectrolytes, the mean particle size of MPs obtained from SEM observations increased from 1.91 to 2.03 μm, and the surface of LbL MPs was smoothened compared to naked CaCO₃ MPs. In addition, the reversible zeta potential changes have confirmed the accomplishment of layer upon a layer assembly. To evaluate the efficiency of cancer therapeutics, we loaded doxorubicin (Dox) in the LbL MPs, which resulted in high (69.7%) drug encapsulation efficiency. The controlled release of Dox resulted in the significant antiproliferative efficiency in breast cancer cell line (MCF-7 cells), demonstrating the potential of applying this innovative drug delivery system in the biomedical field.