Modulation of electrostatic interactions to improve controlled drug delivery from nanogels

An Investigation into the Effects of Processing Factors on the Properties and Scaling-Up Potential of Propranolol-Loaded Chitosan Nanogels

Chitosan-triphosphate (TPP) nanogels are widely studied drug delivery carrier systems, typically prepared via a simple mixing process. However, the effects of the processing factors on nanogel production have not been extensively explored, despite the importance of understanding and standardising such factors to allow upscaling and commercial usage. This study aims to systematically evaluate the effects of various fabrication and processing factors on the properties of nanogels using a Design of Experiment approach. Hydrodynamic size, polydispersity index (PDI), zeta potential, and encapsulation efficiency were determined as the dependent factors. The temperature, stirring rate, chitosan grade, crosslinker choice, and the interaction term between temperature and chitosan grade were found to have a significant effect on the particle size, whereas the effect of temperature and the addition rate of crosslinker on the PDI was also noteworthy. Moreover, the addition rate of the crosslinker and the volume of the reaction vessel were found to impact the encapsulation efficiency. The zeta potential of the nanogels was found to be governed by the chitosan grade. The optimal fabrication conditions for the development of medium molecular weight chitosan and TPP nanogels included the following: the addition rate for TPP solution was set at 2 mL/min, while the solution was then stirred at a temperature of 50 °C and a stirring speed of 600 rpm. The volume of the glass vial used was 28 mL, while the stirrer size was 20 mm. The second aim of the study was to evaluate the potential for scaling up the nanogels. Size and PDI were found to increase from 128 nm to 151 nm and from 0.232 to 0.267, respectively, when the volume of the reaction mixture was increased from 4 to 20 mL and other processing factors were kept unchanged. These results indicate that caution is required when scaling up as the nanogel properties may be significantly altered with an increasing production scale.

Antifouling Zwitterionic Nanofibrous Wound Dressing for Long-Lasting Antibacterial Photodynamic Therapy

Nanofibrous mats as a wound dressing have received great attention in recent year. The development of biocompatible dressings with antibiofouling capability and long-lasting antibacterial properties is important but challenging. Antibacterial photodynamic therapy (aPDT) effectively eliminates pathogens via a photodynamic process that can circumvent the emergence of antibiotic-resistant pathogens. In this study, we integrated the zwitterionic materials (2-methacryloyloxyethyl phosphorylcholine (MPC) moiety) and aPDT photosensitizer, methylene blue (MB), to fabricate a long-lasting antibacterial nanofibrous mat using electrospinning technology. The prepared nanofibers possessed an appropriate water absorption and retention ability, superior cytocompatibility, and antibiofouling ability against both proteins and L929 cell adhesion. MB-loaded nanofibrous mats have exhibited superior aPDT against Gram-positive Staphylococcus aureus compared to Gram-negative Escherichia coli under moderate irradiation (100 W m-2) due to the presence of an extra outer membrane of Gram-negative bacteria serving as a protective barrier. In vitro release study demonstrated that the nanofibrous mat had a long-lasting drug release profile, which can efficiently suppress bacterial growth via aPDT. The antibacterial ability of the MB-loaded nanofibrous mat was commensurate or slightly inferior to antibiotics such as tetracycline and kanamycin, suggesting that it has the potential to be used as an antibiotic alternative. Overall, this zwitterionic nanofibrous mat with long-lasting aPDT function and nonadherent properties has potential as a promising antibacterial wound dressing.

Recent Advancements in Enzyme‐Incorporated Nanomaterials: Synthesis, Mechanistic Formation and Applications

Over the past decade, nanotechnology has been developed and employed across various entities. Among the numerous nanostructured material types, enzyme‐incorporated nanomaterials have shown great potential in various fields, as an alternative to biologically derived as well as synthetically developed hybrid structures. The mechanism of incorporating enzyme onto a nanostructure depends on several factors including the method of immobilization, type of nanomaterial, as well as operational and environmental conditions. The prospects of enzyme‐incorporated nanomaterials have shown promising results across various applications, such as biocatalysts, biosensors, drug therapy, and wastewater treatment. This is due to their excellent ability to exhibit chemical and physical properties such as high surface‐to‐volume ratio, recovery and/or reusability rates, sensitivity, response scale, and stable catalytic activity across wide operating conditions. In this review, the evolution of enzyme‐incorporated nanomaterials along with their impact on our society due to its state‐of‐the‐art properties, and its significance across different industrial applications are discussed. In addition, the weakness and future prospects of enzyme‐incorporated nanomaterials were also discussed to guide scientists for futuristic research and development in this field.

Injectable Natural Polymer Hydrogels for Treatment of Knee Osteoarthritis

Osteoarthritis (OA) is a serious chronic and degenerative disease that increasingly occurs in the aged population. Its current clinical treatments are limited to symptom relief and cannot regenerate cartilage. Although a better understanding of OA pathophysiology has been facilitating the development of novel therapeutic regimen, delivery of therapeutics to target sites with minimal invasiveness, high retention, and minimal side effects remains a challenge. Biocompatible hydrogels have been recognized to be highly promising for controlled delivery and release of therapeutics and biologics for tissue repair. In this review, the current approaches and the challenges in OA treatment, and unique properties of injectable natural polymer hydrogels as delivery system to overcome the challenges are presented. The common methods for fabrication of injectable polysaccharide-based hydrogels and the effects of their composition and properties on the OA treatment are detailed. The strategies of the use of hydrogels for loading and release cargos are also covered. Finally, recent efforts on the development of injectable polysaccharide-based hydrogels for OA treatment are highlighted, and their current limitations are discussed.

Fabrication of Naturally Derived Double-Network Hydrogels With a Sustained Aspirin Release System for Facilitating Bone Regeneration

Continuous efforts on pursuit of effective drug delivery systems for engineering hydrogel scaffolds is considered a promising strategy for the bone-related diseases. Here, we developed a kind of acetylsalicylic acid (aspirin, ASA)–based double-network (DN) hydrogel containing the positively charged natural chitosan (CS) and methacrylated gelatin (GelMA) polymers. Combination of physical chain-entanglement, electrostatic interactions, and a chemically cross-linked methacrylated gelatin (GelMA) network led to the formation of a DN hydrogel, which had a suitable porous structure and favorable mechanical properties. After in situ encapsulation of aspirin agents, the resulting hydrogels were investigated as culturing matrices for adipose tissue–derived stromal cells (ADSCs) to evaluate their excellent biocompatibility and biological capacities on modulation of cell proliferation and differentiation. We further found that the long-term sustained ASA in the DN hydrogels could contribute to the anti-inflammation and osteoinductive properties, demonstrating a new strategy for bone tissue regeneration.

Facile fabrication of a biocompatible composite gel with sustained release of aspirin for bone regeneration

Hydrogels are extracellular-matrix-like biomimetic materials that have wide biomedical applications in tissue engineering and drug delivery. However, most hydrogels cannot simultaneously fulfill the mechanical and cell compatibility requirements. In the present study, we prepared a semi-interpenetrating network composite gel (CG) by incorporating short chain chitosan (CS) into a covalent tetra-armed poly(ethylene glycol) network. In addition to satisfying physicochemical, mechanics, biocompatibility, and cell affinity requirements, this CG easily encapsulated acetylsalicylic acid (ASA) via electrostatic interactions and chain entanglement, achieving sustained release for over 14 days and thus promoting periodontal ligament stem cell (PDLSC) proliferation and osteogenic differentiation. In vivo studies corroborated the capacity of PDLSCs and ASA-laden CG to enhance new bone regeneration in situ using a mouse calvarial bone defect model. This might be attributed to PDLSCs and host mesenchymal stem cells expressing monocyte chemoattractant protein-1, which upregulated M2 macrophage recruitment and polarization in situ, indicating its appealing potential in bone tissue engineering.

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A facile method to prepare the composite gels with advantages of easy operation, good biocompatibility and biodegradability.

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Composite gels can simultaneously fulfill the mechanical strength and cell-compatibility requirements.

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Composite gels can achieve the loading and sustained release of acetylsalicylic acid via electrostatic interaction and chain entanglement.

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Acetylsalicylic-acid-encapsulated composite gel is paramount to promote PDLSCs-mediated bone regeneration.

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The underlying mechanism might be associated with upregulation of MCP-1 and macrophage M2 polarization.

Applications of capillary action in drug delivery

Contrary to the fact that capillary action is ubiquitous in our daily lives, its role in drug delivery has not attracted attention. Therefore, its application in medicine and disease treatment has not been actively developed. This perspective begins by reviewing the principles, advantages, and limitations of the three existing drug delivery strategies: non-covalent interaction, cavity loading, and covalent conjugation. Then, we discussed the principle of capillary action in drug delivery and the influencing factors that determine its performance. To illustrate the advantages of capillary action over existing drug delivery strategies and how the capillary action could potentially address the shortcomings of the existing drug delivery strategies, we described five examples of using capillary action to design drug delivery platforms for disease treatment: marker pen for topical and transdermal drug delivery, microneedle patch with a sponge container for pulsatile drug delivery, core-shell scaffold for sustained release of growth factors, oral bolus for insulin delivery to the esophagus, and semi-hollow floating ball for intravesical and gastroprotective drug delivery. Each of the five drug delivery platforms exhibits certain unique functions that existing drug delivery technologies cannot easily achieve, hence expected to solve specific practical medical problems that are not satisfactorily resolved. As people pay more attention to capillary action and develop more drug delivery platforms, more unique functions and characteristics of capillary action in drug delivery will be explored. Thus, capillary action could become an important choice for drug delivery systems to improve therapeutic drug efficacy, treat diseases, and improve human health.

Biologics and their delivery systems: Trends in myocardial infarction

Cardiovascular disease is the leading cause of death around the world, in which myocardial infarction (MI) is a precipitating event. However, current therapies do not adequately address the multiple dysregulated systems following MI. Consequently, recent studies have developed novel biologic delivery systems to more effectively address these maladies. This review utilizes a scientometric summary of the recent literature to identify trends among biologic delivery systems designed to treat MI. Emphasis is placed on sustained or targeted release of biologics (e.g. growth factors, nucleic acids, stem cells, chemokines) from common delivery systems (e.g. microparticles, nanocarriers, injectable hydrogels, implantable patches). We also evaluate biologic delivery system trends in the entire regenerative medicine field to identify emerging approaches that may translate to the treatment of MI. Future developments include immune system targeting through soluble factor or chemokine delivery, and the development of advanced delivery systems that facilitate the synergistic delivery of biologics.

Nano-encapsulation of hydroxytyrosol into formulated nanogels improves therapeutic effects against hepatic steatosis: An in vitro study

Nanomaterials hold promise as a straightforward approach for enhancing the performance of bioactive compounds in several healthcare scenarios. Indeed, nanoencapsulation represents a valuable strategy to preserve the bioactives, maximizing their bioavailability. Here, a nanoencapsulation strategy for the treatment of nonalcoholic fatty liver disease (NAFLD) is presented. NAFLD represents the most common chronic liver disease in Western societies, and still lacks an effective therapy. Hydroxytyrosol (HT), a naturally occurring polyphenol, has been shown to protect against hepatic steatosis through its lipid-lowering, antioxidant and anti-inflammatory activities. However, the efficient delivery of HT to hepatocytes remains a crucial aspect: the design of smart nanogels appears as a promising tool to promote its intracellular uptake. In this paper, we disclose the synthesis of nanogel systems based on polyethylene glycol and polyethyleneimine which have been tested in an in vitro model of hepatic steatosis at two different concentrations (0.1 mg/mL and 0.5 mg/mL), taking advantage of high-content analysis tools. The proposed HT-loaded nanoscaffolds are non-toxic to cells, and their administration showed a significant decrease in the intracellular triglyceride levels, restoring cell viability and outperforming the results achievable with HT in its non-encapsulated form. Moreover, nanogels do not induce oxidative stress, thus demonstrating their biosafety. Overall, the formulated nanogel system achieves superior performance compared to conventional drug administration routes and hence represents a promising strategy for the management of NAFLD.

Chitosan Derivatives in Macromolecular Co-assembly Nanogels with Potential for Biomedical Applications

Maleoyl-chitosan/poly(aspartic acid) nanogels were developed and characterized in order to assess its suitability for biomedical applications. Thus, the physicochemical properties were investigated and correlated with the composition of the new structures. Dynamic light scattering measurements, correlated with transmission electron microscopy images, demonstrated that nanogels size distribution was narrow with average diameter between 186 and 246 nm, and presented positive zeta potential values. The sensitivity of nanogels at pH and temperature was also evaluated. Nanogels loaded with amoxicillin showed a controlled release profile dependent on nanogel content. The formulations loaded with amoxicillin had antibacterial properties, and the cytotoxicity tests indicated good in vivo biocompatibility. In conclusion, the new synthesized polyelectrolyte nanogels, which can provide a stable environment for the encapsulated drugs, can be used as a multifunctional platform for administration of antimicrobial agents from the spectrum of antibiotics that have a very poor biodistribution.

Octadecyltrichlorosilane Incorporated Alginate Micro-granules as Sustained-Release Carriers for Small Hydrophilic Molecules

Background:

Hydrogels are excellent drug carriers, but their inability to retain hydrophilic drugs for a prolonged period of time has greatly limited their usage. Research has mostly focused on intricate designs and manipulations of hydrogels to expand their applications in drug delivery.

Objective:

In this study, a simple approach by incorporating a hydrophobic agent, octadecyltrichlorosilane (OTS), to alginate hydrogel micro-granules (Alg-Ms), was investigated as an effective technique to prolong the release of small hydrophilic drugs.

Methods:

Sodium Benzoate (SB), a highly water-soluble antimicrobial and anti-inflammatory compound, was used as a model drug. The presence of hydrophobic OTS impeded swelling of these OTS incorporated Alg-Ms (OTS-Alg-Ms), hence sustaining the release of SB.

Results:

The release data was fitted with Ritger-Peppas and Peppas-Sahlin models and the results showed that SB released from OTS-Alg-Ms with higher OTS content was mainly controlled by Fickian diffusion; with a lower OTS content, OTS-Alg-Ms swelled more easily, the combined diffusion and swelling led to a faster SB release.

Conclusion:

Thus, by simply tuning the OTS concentration in the solution where Alg-Ms were briefly submerged in a predefined release period, from hours to a few days, small hydrophilic drugs from these OTS-Alg-Ms could be successfully achieved.

Ultrashort Peptide Self-Assembly: Front-Runners to Transport Drug and Gene Cargos

The translational therapies to promote interaction between cell and signal come with stringent eligibility criteria. The chemically defined, hierarchically organized, and simpler yet blessed with robust intermolecular association, the peptides, are privileged to make the cut-off for sensing the cell-signal for biologics delivery and tissue engineering. The signature service and insoluble network formation of the peptide self-assemblies as hydrogels have drawn a spell of research activity among the scientists all around the globe in the past decades. The therapeutic peptide market players are anticipating promising growth opportunities due to the ample technological advancements in this field. The presence of the other organic moieties, enzyme substrates and well-established protecting groups like Fmoc and Boc etc., bring the best of both worlds. Since the large sequences of peptides severely limit the purification and their isolation, this article reviews the account of last 5 years' efforts on novel approaches for formulation and development of single molecule amino acids, ultra-short peptide self-assemblies (di- and tri- peptides only) and their derivatives as drug/gene carriers and tissue-engineering systems.

Nanogels for Skin Cancer Therapy via Transdermal Delivery: Current Designs

BACKGROUND

Recently, several strategies have been proposed for skin cancer therapy by transdermal delivery, and particularly the use of nanotechnology.

METHODS

This process disrupts the stratum corneum to deliver a drug through the skin, allowing it to accumulate at the tumor site.

RESULTS

Nanogels are drug delivery systems that can be applied to many diseases. Nanogel engineering has been widely studied for use in drug delivery, particularly in cancer theranostics. This review summarizes specific strategies for using nanogels to treat skin cancer, a topic that is limited in recent literature.

CONCLUSION

Advanced techniques for effective skin cancer therapy based on the nanogel's penetration and cellular uptake abilities will be discussed. Moreover, techniques for penetrating the skin, as well as drug release, permeation studies, and microscopic observations, will also be discussed.

Polyethylenimine-Based Nanogels for Biomedical Applications

Nanogels (NGs) are 3-dimensional (3D) networks composed of hydrophilic or amphiphilic polymer chains, allowing for effective and homogeneous encapsulation of drugs, genes, or imaging agents for biomedical applications. Polyethylenimine (PEI), possessing abundant positively charged amine groups, is an ideal platform for the development of NGs. A variety of effective PEI-based NGs have been designed and much effort has been devoted to study the relationship between the structure and function of the NGs. In particular, PEI-based NGs can be prepared either using PEI as the major NG component or using PEI as a crosslinker. This review reports the recent progresses in the design of PEI-based NGs for gene and drug delivery and for bioimaging applications with a target focus to tackle the diagnosis and therapy of cancer.

Evaluation of cationic core-shell thermoresponsive poly(N-vinylcaprolactam)-based microgels as potential drug delivery nanocarriers

The present work investigates the potentiality of poly(N-vinyl caprolactam) (PVCL)-based thermoresponsive microgels decorated with cationic polymer brushes as drug delivery carriers. The effect of physico-chemical features of the colloids on cell viability response have to be carefully investigated to establish the range of suitable hydrodynamic diameters, crosslinking densities, lengths and ratios of the cationic polyelectrolyte shell which allow their efficient and effective use for cargo loading, transport and delivery. The colloidal stability of all cationic thermoresponsive microgels is maintained over several days of incubation at 37 °C in biological mimicking medium (Dulbecco's Modified Eagle's Medium supplemented with fetal bovine serum). The thin cationic polymer shell covalently anchored does not hinder the all range of microgels to be biocompatible while the higher cytotoxicity of the doxorubicin-loaded microgels on HeLa cells proves their anti-tumor activity. The core-shell PVCL drug delivery nanocarriers allow a sustained release of doxorubicin with a slightly higher viability of HeLa cells incubated in the presence of DOXO-loaded microgels compared to the free DOXO. The nature of the endocytosis pathway is investigated through a quantification of the extent of the cellular survival rate in the presence of various cellular uptake inhibitors. A clathrin-dependent internalization was observed.

Design of polymer-based antimicrobial hydrogels through physico-chemical transition

The antimicrobial activity represents a cornerstone in the development of biomaterials: it is a leading request in many areas, including biology, medicine, environment and industry. Over the years, different polymeric scaffolds are proposed as solutions, based on the encapsulation of metal ions/particles, antibacterial agents or antibiotics. However, the compliance with the biocompatibility criteria and the concentration of the active principles to avoid under- and over-dosing are being debated. In this work, we propose the synthesis of a versatile hydrogel using branched polyacrylic acid (carbomer 974P) and aliphatic polyetherdiamine (elastamine®) through physico-chemical transition, able to show its ability to counteract the bacterial growth and infections thanks to the polymers used, that are not subjected to further chemical modifications. In particular, the antimicrobial activity is clearly demonstrated against Staphyloccoccus aureus and Candida albicans, two well-known opportunistic pathogens. Moreover, we discuss the hydrogel use as drug carrier to design a unique device able to combine the antibacterial/antimicrobial properties to the controlled drug delivery, as a promising tool for a wide range of biomedical applications.

Zwitterionic carbon dot-encapsulating pH-responsive mesoporous silica nanoparticles for NIR light-triggered photothermal therapy through pH-controllable release

Here, we designed a pH-responsive Indocyanine Green (ICG)-loaded zwitterionic fluorescent carbon dot (CD)-encapsulating mesoporous silica nanoparticle (MSN) for pH-tunable image-guided photothermal therapy.

Non-Gaussian elasticity and charge density-dependent swelling of strong polyelectrolyte poly(N-isopropylacrylamide-co-sodium acrylate) hydrogels

The mechanical properties and charge density-dependent swelling of strong polyelectrolyte poly(N-isopropylacrylamide-co-sodium acrylate) P(NIPA-co-NaA) hydrogels prepared at a fixed total monomer concentration and crosslinker ratio, but at various charge densities, i.e. NaA content in the feed between 0 and 90 mol%, were investigated. The elasticity results were discussed to explain the relationship between the elastic free energy ΔG_el and the swelling ratio α as well as to fit the existing theories to the swelling data. The implications of the obtained results for the deviation from the Gaussian chain statistics were considered. Given the swollen elastic modulus and the dependence of charge density on the equilibrium gel volume, it would seem that the latter factor is an important determinant of non-Gaussian elasticity of polyelectrolyte P(NIPA-co-NaA) hydrogels containing strongly dissociated groups. The dependence of the reduced modulus on the equilibrium gel volume was found to be G_r ≈ (V_eq)^-0.47 at low swelling degree and G_r ≈ (V_eq)^0.64 at high swelling degree and the deviation was interpreted as the non-Gaussian elasticity of equilibrium swollen P(NIPA-co-NaA) hydrogels. The detailed theoretical treatments of non-Gaussian elasticity of P(NIPA-co-NaA) hydrogels and, in particular, the influence of the charge density on the elasticity showed that the knowledge of several swollen state parameters and the effective charge density distribution of hydrogels were strongly required to explain the variation of the elastic properties depending on the ionic group content. Within this framework, the dominant mechanism responsible for the deviation from Gaussian elasticity and the finite chain extensibility of ionic P(NIPA-co-NaA) hydrogels was described and the results were used to explain the dependence of the elastic modulus on the equilibrium gel volume.

Dual-responsive core-crosslinked polyphosphoester-based nanoparticles for pH/redox-triggered anticancer drug delivery

The paper focuses on the preparation of biodegradable pH/redox dual-responsive core-crosslinked nanoparticles loaded with dual anticancer drugs PTX and DOX via synergetic electrostatic as well as hydrophobic interactions and their further application in tumor chemotherapy.