Polymeric nanoparticles and microparticles for the delivery of peptides, biologics, and soluble therapeutics

Restoring physiological parameters of the pancreas and kidney through treatment with a polymeric nano-formulation of C-peptide and lisofylline combination in diabetic nephropathy

Diabetic nephropathy (DN) is a progressive kidney disorder that develops as a complication of diabetes due to long-term exposure to elevated blood glucose levels (BGLs). In this case, an intervention of therapeutic moieties is needed to target the specific elements involved in diabetes to prevent/delay the deterioration of kidney function. Therefore, the present study focused on designing and evaluating a potent nano-formulation of a combination of C-peptide (CPep) and the anti-diabetic drug lisofylline (LSF) to prevent streptozotocin (STZ)-induced DN. As a strategic intervention, an LSF-oleic acid prodrug (LSF-OA) was initially synthesized and further encapsulated in an in-house-synthesized cationic polymer [(mPEG-b-P(CB-{g-DMDP}-co-LA)); mPLM] to prepare polymeric nano-complexes of CPep via electrostatic interaction, possessing a size of 218.6 ± 14.4 nm and zeta potential of +5.2 mV together with stability for 30 days at 25 °C. mPLM-LSF-OA-CPep nanoparticles demonstrated hemocompatibility with RBCs and exhibited potent anti-oxidant activity by reducing nitrite levels, inducing the release of anti-oxidant GSH and protecting metabolically stressed rat kidneys and murine insulinoma cells from apoptosis. In vivo pharmacokinetics depicted an increase in t½ and mean residence time in rats, which further improved the BGL and renal conditions and reduced plasma IL-6 and TNF-α levels in the STZ-induced DN animal model when treated with mPLM-LSF-OA-CPep compared to free LSF and CPep. Moreover, an increase in the plasma insulin level and detection of proliferative marker cells in pancreatic islets suggested the regeneration of β-cells in diabetic animals.

Identification and Characterization of Critical Processing Parameters in the Fabrication of Double-Emulsion Poly(lactic-co-glycolic) Acid Microparticles

In the past several decades, polymeric microparticles (MPs) have emerged as viable solutions to address the limitations of standard pharmaceuticals and their corresponding delivery methods. While there are many preclinical studies that utilize polymeric MPs as a delivery vehicle, there are limited FDA-approved products. One potential barrier to the clinical translation of these technologies is a lack of understanding with regard to the manufacturing process, hindering batch scale-up. To address this knowledge gap, we sought to first identify critical processing parameters in the manufacturing process of blank (no therapeutic drug) and protein-loaded double-emulsion poly(lactic-co-glycolic) acid MPs through a quality by design approach. We then utilized the design of experiments as a tool to systematically investigate the impact of these parameters on critical quality attributes (e.g., size, surface morphology, release kinetics, inner occlusion size, etc.) of blank and protein-loaded MPs. Our results elucidate that some of the most significant CPPs impacting many CQAs of double-emulsion MPs are those within the primary or single-emulsion process (e.g., inner aqueous phase volume, solvent volume, etc.) and their interactions. Furthermore, our results indicate that microparticle internal structure (e.g., inner occlusion size, interconnectivity, etc.) can heavily influence protein release kinetics from double-emulsion MPs, suggesting it is a crucial CQA to understand. Altogether, this study identifies several important considerations in the manufacturing and characterization of double-emulsion MPs, potentially enhancing their translation.

Development of 225Ac-doped biocompatible nanoparticles for targeted alpha therapy

Targeted alpha therapy (TAT) relies on chemical affinity or active targeting using radioimmunoconjugates as strategies to deliver α-emitting radionuclides to cancerous tissue. These strategies can be affected by transmetalation of the parent radionuclide by competing ions in vivo and the bond-breaking recoil energy of decay daughters. The retention of α-emitting radionuclides and the dose delivered to cancer cells are influenced by these processes. Encapsulating α-emitting radionuclides within nanoparticles can help overcome many of these challenges. Poly(lactic-co-glycolic acid) (PLGA) nanoparticles are a biodegradable and biocompatible delivery platform that has been used for drug delivery. In this study, PLGA nanoparticles are utilized for encapsulation and retention of actinium-225 ([225Ac]Ac3+). Encapsulation of [225Ac]Ac3+ within PLGA nanoparticles (Zave = 155.3 nm) was achieved by adapting a double-emulsion solvent evaporation method. The encapsulation efficiency was affected by both the solvent conditions and the chelation of [225Ac]Ac3+. Chelation of [225Ac]Ac3+ to a lipophilic 2,9-bis-lactam-1,10-phenanthroline ligand ([225Ac]AcBLPhen) significantly decreased its release (< 2%) and that of its decay daughters (< 50%) from PLGA nanoparticles. PLGA nanoparticles encapsulating [225Ac]AcBLPhen significantly increased the delivery of [225Ac]Ac3+ to murine (E0771) and human (MCF-7 and MDA-MB-231) breast cancer cells with a concomitant increase in cell death over free [225Ac]Ac3+ in solution. These results demonstrate that PLGA nanoparticles have potential as radionuclide delivery platforms for TAT to advance precision radiotherapy for cancer. In addition, this technology offers an alternative use for ligands with poor aqueous solubility, low stability, or low affinity, allowing them to be repurposed for TAT by encapsulation within PLGA nanoparticles.

Influence of Polymeric Microparticle Size and Loading Concentration on 3D Printing Accuracy and Degradation Behavior of Composite Scaffolds

Successful employment of 3D printing for delivery of therapeutic biomolecules requires protection of their bioactivity on exposure to potentially inactivating conditions. Although intermediary encapsulation of the biomolecules in polymeric particulate delivery vehicles is a promising strategy for this objective, the inclusion of such particles in 3D printing formulations may critically impact the accuracy or precision of 3D printed scaffolds relative to their intended designed architectures, as well as the degradation behavior of both the scaffolds and the included particles. The present work aimed to elucidate the effect of poly(d,l-lactic-co-glycolic acid) particle size and loading concentration on material accuracy, machine precision, and degradation of 3D printed poly(ɛ-caprolactone)-based scaffolds. Using a main effects analysis, the sizes and loading concentrations of particle delivery vehicles investigated were found to have neither a beneficial nor disadvantageous influence on the metrics of printing quality such as material accuracy and machine precision. Meanwhile, particle loading concentration was determined to influence degradation rate, whereas printing temperature affected the trends in composite weight-average molecular weight. Neither of the two particle-related parameters (concentration nor diameter) was found to exhibit a significant effect on intra-fiber nor inter-fiber porosity. These findings evidence the capacity for controlled loading of particulate delivery vehicles in 3D printed scaffolds while preserving construct accuracy and precision, and with predictable dictation of composite degradation behavior for potential controlled release of encapsulated biomolecules.

Flash NanoPrecipitation as an Agrochemical Nanocarrier Formulation Platform: Phloem Uptake and Translocation after Foliar Administration

The increasing severity of pathogenic and environmental stressors that negatively affect plant health has led to interest in developing next-generation agrochemical delivery systems capable of precisely transporting active agents to specific sites within plants. In this work, we adapt Flash NanoPrecipitation (FNP), a scalable nanocarrier (NC) formulation technology used in the pharmaceutical industry, to prepare organic core-shell NCs and study their efficacy as foliar or root delivery vehicles. NCs ranging in diameter from 55 to 200 nm, with surface zeta potentials from -40 to +40 mV, and with seven different shell material properties were prepared and studied. Shell materials included synthetic polymers poly(acrylic acid), poly(ethylene glycol), and poly(2-(dimethylamino)ethyl methacrylate), naturally occurring compounds fish gelatin and soybean lecithin, and semisynthetic hydroxypropyl methylcellulose acetate succinate (HPMCAS). NC cores contained a gadolinium tracer for tracking by mass spectrometry, a fluorescent dye for tracking by confocal microscopy, and model hydrophobic compounds (alpha tocopherol acetate and polystyrene) that could be replaced by agrochemical payloads in subsequent applications. After foliar application onto tomato plants with Silwet L-77 surfactant, internalization efficiencies of up to 85% and NC translocation efficiencies of up to 32% were observed. Significant NC trafficking to the stem and roots suggests a high degree of phloem loading for some of these formulations. Results were corroborated by confocal microscopy and synchrotron X-ray fluorescence mapping. NCs stabilized by cellulosic HPMCAS exhibited the highest degree of translocation, followed by formulations with a significant surface charge. The results from this work indicate that biocompatible materials like HPMCAS are promising agrochemical delivery vehicles in an industrially viable pharmaceutical nanoformulation process (FNP) and shed light on the optimal properties of organic NCs for efficient foliar uptake, translocation, and delivery.

Influence of drug molecular weight on self-assembly and intestinal permeation of polymer-based nanocarriers

For oral delivery, the physicochemical properties of nanocarriers are decisive factors for permeation through the intestinal epithelium. These properties are determined by the composition of the nanocarriers as well as by the process parameters during their self-assembly. For macromolecular drugs, there is still little understanding of the drug-polymer interactions during nanocarrier self-assembly and the effects on carrier properties. In this study, the effect of drug molecular weight on nanocarrier self-assembly, physicochemical properties of nanocarriers as well as their permeation across the intestinal epithelium was investigated. Our results show that the drug molecular weight impacts the physicochemical properties of nanocarriers. Further, the physicochemical properties of the nanocarriers, governed by the molecular weight of the drug, determine their permeation properties across the intestinal epithelium. Comparative in vitro and ex vivo studies revealed that intestinal absorption is dependent on both, the properties of the tissue as well as properties of the carrier system. In conclusion, the molecular weight of drug payload is a key factor determining the physiochemical properties of polymeric nanocarriers and is closely linked to their oral absorption. Using different preclinical models to evaluate intestinal permeation of nanocarriers allows for novel insights into key formulation properties governing oral bioavailability.

PLGA-based electrospun nanofibers loaded with dual bioactive agent loaded scaffold as a potential wound dressing material

Chronic and infectious wounds are major public health issues with financial and clinical manifestations. Developing a multitasking extracellular matrix mimicking scaffold can bring revolution saving millions of lives. Many bioactive agents are offering therapeutic promises in managing infectious wounds but require a suitable delivery system to ensure not only their bioavailability possible on the wound site but also control their burst release hence making them either useless or highly cytotoxic. In this study, we reported the dual bioactive agent-loaded electrospinning nanofibers potentially useable against infectious wounds. The zinc oxide nanoparticles (ZnO NPs) and vascular endothelial growth factors (VEGF), highly relevant bioactive agents, were chosen to be co-delivered to the wound site through the core-shell electrospun membrane. The physicochemical properties of prepared membranes were characterized through various physicochemical tools. Our result demonstrated that PLGA polymer can be electrospun into smooth fibers. X-ray diffraction analysis revealed the successful loading of ZnO NPs which was further confirmed by TEM. The fabricated membrane exhibited a suitable mechanical behavior. Moreover, the incorporation of ZnO NPs has turned the nanofibers into an effective antibacterial scaffold. Besides, the membranes were also evaluated for their cytotoxicity. The in vitro cell culturing on various membranes revealed that cell maintained their maximum viability on all the membranes. The potential of in vivo wound healing was further demonstrated through animal experiments. Our results show that membranes could not only influence early wound contraction, but also better tissue organization demonstrated through histopathological evaluation. We successfully demonstrated the rich vascularization network by synching the actions of ZnO NPs and VEGF. In conclusion, the fabricated membranes possess suitable physicochemical properties and promising biological activity and hence should be further exploited for in vivo wound healing potential.

The battle of lipid-based nanocarriers against blood-brain barrier: a critical review

Central nervous system integrity is the state of brain functioning across sensory, cognitive, emotional-social behaviors, and motor domains, allowing a person to realise his full potential. Thus, brain disorders seriously affect patients' quality of life. Efficient drug delivery to treat brain disorders remains a crucial challenge due to numerous brain barriers, particularly the blood-brain barrier (BBB), which greatly impacts the ultimate drug therapeutic efficacy. Lately, nanocarrier technology has made huge progress in overcoming these barriers by improving drug solubility, ameliorating its retention, reducing its toxicity, and targeting the encapsulated agents to different brain tissues. The current review primarily offers an overview of the different components of BBB and the progress, strategies, and contemporary applications of the nanocarriers, specifically lipid-based nanocarriers (LBNs), in treating various brain disorders.

Rational nanoparticle design: Optimization using insights from experiments and mathematical models

Polymeric nanoparticles are highly tunable drug delivery systems that show promise in targeting therapeutics to specific sites within the body. Rational nanoparticle design can make use of mathematical models to organize and extend experimental data, allowing for optimization of nanoparticles for particular drug delivery applications. While rational nanoparticle design is attractive from the standpoint of improving therapy and reducing unnecessary experiments, it has yet to be fully realized. The difficulty lies in the complexity of nanoparticle structure and behavior, which is added to the complexity of the physiological mechanisms involved in nanoparticle distribution throughout the body. In this review, we discuss the most important aspects of rational design of polymeric nanoparticles. Ultimately, we conclude that many experimental datasets are required to fully model polymeric nanoparticle behavior at multiple scales. Further, we suggest ways to consider the limitations and uncertainty of experimental data in creating nanoparticle design optimization schema, which we call quantitative nanoparticle design frameworks.

Preserving and enhancing mitochondrial function after stroke to protect and repair the neurovascular unit: novel opportunities for nanoparticle-based drug delivery

The neurovascular unit (NVU) is composed of vascular cells, glia, and neurons that form the basic component of the blood brain barrier. This intricate structure rapidly adjusts cerebral blood flow to match the metabolic needs of brain activity. However, the NVU is exquisitely sensitive to damage and displays limited repair after a stroke. To effectively treat stroke, it is therefore considered crucial to both protect and repair the NVU. Mitochondrial calcium (Ca2+) uptake supports NVU function by buffering Ca2+ and stimulating energy production. However, excessive mitochondrial Ca2+ uptake causes toxic mitochondrial Ca2+ overloading that triggers numerous cell death pathways which destroy the NVU. Mitochondrial damage is one of the earliest pathological events in stroke. Drugs that preserve mitochondrial integrity and function should therefore confer profound NVU protection by blocking the initiation of numerous injury events. We have shown that mitochondrial Ca2+ uptake and efflux in the brain are mediated by the mitochondrial Ca2+ uniporter complex (MCUcx) and sodium/Ca2+/lithium exchanger (NCLX), respectively. Moreover, our recent pharmacological studies have demonstrated that MCUcx inhibition and NCLX activation suppress ischemic and excitotoxic neuronal cell death by blocking mitochondrial Ca2+ overloading. These findings suggest that combining MCUcx inhibition with NCLX activation should markedly protect the NVU. In terms of promoting NVU repair, nuclear hormone receptor activation is a promising approach. Retinoid X receptor (RXR) and thyroid hormone receptor (TR) agonists activate complementary transcriptional programs that stimulate mitochondrial biogenesis, suppress inflammation, and enhance the production of new vascular cells, glia, and neurons. RXR and TR agonism should thus further improve the clinical benefits of MCUcx inhibition and NCLX activation by increasing NVU repair. However, drugs that either inhibit the MCUcx, or stimulate the NCLX, or activate the RXR or TR, suffer from adverse effects caused by undesired actions on healthy tissues. To overcome this problem, we describe the use of nanoparticle drug formulations that preferentially target metabolically compromised and damaged NVUs after an ischemic or hemorrhagic stroke. These nanoparticle-based approaches have the potential to improve clinical safety and efficacy by maximizing drug delivery to diseased NVUs and minimizing drug exposure in healthy brain and peripheral tissues.

Eco-friendly chitosan-based nanostructures in diabetes mellitus therapy: Promising bioplatforms with versatile therapeutic perspectives

Nature-derived polymers, or biopolymers, are among the most employed materials for the development of nanocarriers. Chitosan (CS) is derived from the acetylation of chitin, and this biopolymer displays features such as biocompatibility, biodegradability, low toxicity, and ease of modification. CS-based nano-scale delivery systems have been demonstrated to be promising carriers for drug and gene delivery, and they can provide site-specific delivery of cargo. Owing to the high biocompatibility of CS-based nanocarriers, they can be used in the future in clinical trials. On the other hand, diabetes mellitus (DM) is a chronic disease that can develop due to a lack of insulin secretion or insulin sensitivity. Recently, CS-based nanocarriers have been extensively applied for DM therapy. Oral delivery of insulin is the most common use of CS nanoparticles in DM therapy, and they improve the pharmacological bioavailability of insulin. Moreover, CS-based nanostructures with mucoadhesive features can improve oral bioavailability of insulin. CS-based hydrogels have been developed for the sustained release of drugs and the treatment of DM complications such as wound healing. Furthermore, CS-based nanoparticles can mediate delivery of phytochemicals and other therapeutic agents in DM therapy, and they are promising compounds for the treatment of DM complications, including nephropathy, neuropathy, and cardiovascular diseases, among others. The surface modification of nanostructures with CS can improve their properties in terms of drug delivery and release, biocompatibility, and others, causing high attention to these nanocarriers in DM therapy.

Biomedical applications of PLGA nanoparticles in nanomedicine: advances in drug delivery systems and cancer therapy

INTRODUCTION

During the last decades, the ever-increasing proportion of patients with cancer has been led to serious concerns worldwide. Therefore, the development and use of novel pharmaceuticals, like nanoparticles (NPs)-based drug delivery systems (DDSs), can be potentially effective in cancer therapy.

AREA COVERED

Poly lactic-co-glycolic acid (PLGA) NPs, as a kind of bioavailable, biocompatible, and biodegradable polymers, have approved by the Food and Drug Administration (FDA) for some biomedical and pharmaceutical applications. PLGA is comprised of lactic acid (LA) and glycolic acid (GA) and their ratio could be controlled during various syntheses and preparation approaches. LA/GA ratio determines the stability and degradation time of PLGA; lower content of GA results in fast degradation. There are several approaches for preparing PLGA NPs that can affect their various aspects, such as size, solubility, stability, drug loading, pharmacokinetics, and pharmacodynamics, and so on.

EXPERT OPINION

These NPs have indicated the controlled and sustained drug release in the cancer site and can use in passive and active (via surface modification) DDSs. This review aims to provide an overview of PLGA NPs, their preparation approach and physicochemical aspects, drug release mechanism and the cellular fate, DDSs for efficient cancer therapy, and status in the pharmaceutical industry and nanomedicine.

A Recent Review on Cancer Nanomedicine

Cancer is one of the most prevalent diseases globally and is the second major cause of death in the United States. Despite the continuous efforts to understand tumor mechanisms and various approaches taken for treatment over decades, no significant improvements have been observed in cancer therapy. Lack of tumor specificity, dose-related toxicity, low bioavailability, and lack of stability of chemotherapeutics are major hindrances to cancer treatment. Nanomedicine has drawn the attention of many researchers due to its potential for tumor-specific delivery while minimizing unwanted side effects. The application of these nanoparticles is not limited to just therapeutic uses; some of them have shown to have extremely promising diagnostic potential. In this review, we describe and compare various types of nanoparticles and their role in advancing cancer treatment. We further highlight various nanoformulations currently approved for cancer therapy as well as under different phases of clinical trials. Finally, we discuss the prospect of nanomedicine in cancer management.

Encapsulation of PI3K Inhibitor LY294002 within Polymer Nanoparticles Using Ion Pairing Flash Nanoprecipitation

Flash nanoprecipitation (FNP) is a turbulent mixing process capable of reproducibly producing polymer nanoparticles loaded with active pharmaceutical ingredients (APIs). The nanoparticles produced with this method consist of a hydrophobic core surrounded by a hydrophilic corona. FNP produces nanoparticles with very high loading levels of nonionic hydrophobic APIs. However, hydrophobic compounds with ionizable groups are not as efficiently incorporated. To overcome this, ion pairing agents (IPs) can be incorporated into the FNP formulation to produce highly hydrophobic drug salts that efficiently precipitate during mixing. We demonstrate the encapsulation of the PI3K inhibitor, LY294002, within poly(ethylene glycol)-b-poly(D,L lactic acid) nanoparticles. We investigated how incorporating two hydrophobic IPs (palmitic acid (PA) and hexadecylphosphonic acid (HDPA)) during the FNP process affected the LY294002 loading and size of the resulting nanoparticles. The effect of organic solvent choice on the synthesis process was also examined. While the presence of either hydrophobic IP effectively increased the encapsulation of LY294002 during FNP, HDPA resulted in well-defined colloidally stable particles, while the PA resulted in ill-defined aggregates. The incorporation of hydrophobic IPs with FNP opens the door for the intravenous administration of APIs that were previously deemed unusable due to their hydrophobic nature.

Polymeric nanomaterial strategies to encapsulate and deliver biological drugs: points to consider between methods

Biological drugs (BDs) play an increasingly irreplaceable role in treating various diseases such as cancer, and cardiovascular and neurodegenerative diseases. The market share of BDs is increasingly promising. However, the effectiveness of BDs is currently limited due to challenges in efficient administration and delivery, and issues with stability and degradation. Thus, the field is using nanotechnology to overcome these limitations. Specifically, polymeric nanomaterials are common BD carriers due to their biocompatibility and ease of synthesis. Different strategies are available for BD transportation, but the use of core-shell encapsulation is preferable for BDs. This review discusses recent articles on manufacturing methods for encapsulating BDs in polymeric materials, including emulsification, nanoprecipitation, self-encapsulation and coaxial electrospraying. The advantages and disadvantages of each method are analysed and discussed. We also explore the impact of critical synthesis parameters on BD activity, such as sonication in emulsifications. Lastly, we provide a vision of future challenges and perspectives for scale-up production and clinical translation.

Effects of the polymer glass transition on the stability of nanoparticle dispersions

In addition to the repulsive and attractive interaction forces described by Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, many charged colloid systems are stabilized by non-DLVO contributions stemming from specific material attributes. Here, we investigate non-DLVO contributions to the stability of polymer colloids stemming from the intra-particle glass transition temperature (T_g). Flash nanoprecipitation is used to fabricate nanoparticles (NPs) from a library of polymers and dispersion stability is studied in the presence of both hydrophilic and hydrophobic salts. When adding KCl, stability undergoes a discontinuous decrease as T_g increases above room temperature, indicating greater stability of rubbery NPs over glassy NPs. Glassy NPs are also found to interact strongly with hydrophobic phosphonium cations (PR₄⁺), yielding charge inversion and intermediate aggregation while rubbery NPs resist ion adsorption. Differences in the lifetime of ionic structuration within mobile surface layers is presented as a potential mechanism underlying the observed phenomenon.

Selecting Counterions to Improve Ionized Hydrophilic Drug Encapsulation in Polymeric Nanoparticles

Hydrophobic ion pairing (HIP) can successfully increase the drug loading and control the release kinetics of ionizable hydrophilic drugs, addressing challenges that prevent these molecules from reaching the clinic. Nevertheless, polymeric nanoparticle (PNP) formulation development requires trial-and-error experimentation to meet the target product profile, which is laborious and costly. Herein, we design a preformulation framework (solid-state screening, computational approach, and solubility in PNP-forming emulsion) to understand counterion-drug-polymer interactions and accelerate the PNP formulation development for HIP systems. The HIP interactions between a small hydrophilic molecule, AZD2811, and counterions with different molecular structures were investigated. Cyclic counterions formed amorphous ion pairs with AZD2811; the 0.7 pamoic acid/1.0 AZD2811 complex had the highest glass transition temperature (T_g; 162 °C) and the greatest drug loading (22%) and remained as phase-separated amorphous nanosized domains inside the polymer matrix. Palmitic acid (linear counterion) showed negligible interactions with AZD2811 (crystalline-free drug/counterion forms), leading to a significantly lower drug loading despite having similar log P and pK_a with pamoic acid. Computational calculations illustrated that cyclic counterions interact more strongly with AZD2811 than linear counterions through dispersive interactions (offset π-π interactions). Solubility data indicated that the pamoic acid/AZD2811 complex has a lower organic phase solubility than AZD2811-free base; hence, it may be expected to precipitate more rapidly in the nanodroplets, thus increasing drug loading. Our work provides a generalizable preformulation framework, complementing traditional performance-indicating parameters, to identify optimal counterions rapidly and accelerate the development of hydrophilic drug PNP formulations while achieving high drug loading without laborious trial-and-error experimentation.

Hydrophobic ion pairing-based self-emulsifying drug delivery systems: a new strategy for improving the therapeutic efficacy of water-soluble drugs

INTRODUCTION

Self-emulsifying drug delivery systems (SEDDS) are formulations consisting of oil phase, emulsifiers, and co-emulsifiers, which can be spontaneously emulsified in the body to form O/W microemulsion. Traditionally, SEDDS are used commercially for the improvement of oral absorption and in vivo performances for poorly water-soluble drugs. However, SEDDS formulations were rarely reported for the delivery of water-soluble drugs. Recent studies have found that SEDDS have the potential for water-soluble macromolecular drugs by the application of the hydrophobic ion pairing (HIP) technology.

AREAS COVERED

This review summarized the characteristics of HIP complexes in SEDDS and introduced their advantages and discussed the future prospects of HIP-based SEDDS in drug delivery.

EXPERT OPINION

Hydrophobic ion pairing (HIP) is a technology that combines lipophilic structures on polar counterions to increase the lipophilicity through electrostatic interaction. Recent studies showed that HIP-based SEDDS offer an effective way to increase the mucosal permeability and improve the chemical stability for antibiotics, proteases, DNA-based drugs, and other water-soluble macromolecular drugs. It is believed that HIP-based SEDDS offer a potential and attractive method capable of delivering hydrophilic macromolecules with ionizable groups for oral administration.

Bevacizumab-Controlled Delivery from Polymeric Microparticle Systems as Interesting Tools for Pathologic Angiogenesis Diseases

This work is a comparative study among three different biocompatible and biodegradable polymers, poly(lactic-co-glycolic acid), poly(ε-caprolactone), and poly(lactic acid), used to produce microparticles for the encapsulation of bevacizumab for drug delivery purposes. All the formulations were produced using the double emulsion water-oil-water evaporation method and characterized in terms of particle mean diameter, particle size distribution, and bevacizumab entrapment efficiency. Bevacizumab cumulative release was taken into consideration to study the dissolution kinetics from the three different polymeric delivery platforms for a period of 50 days at 37 °C in phosphate buffered saline and mathematical models of the drug release kinetic were attempted in order to describe the release phenomena from the different types of the studied microparticles. Finally, cell viability on human endothelial cell line EA.hy926 was studied to define the maximum cytocompatible concentration for each microsystem, registering the mitochondrial functionality through MTS assay.

Poly(Lactic Acid)-Based Microparticles for Drug Delivery Applications: An Overview of Recent Advances

The sustained release of pharmaceutical substances remains the most convenient way of drug delivery. Hence, a great variety of reports can be traced in the open literature associated with drug delivery systems (DDS). Specifically, the use of microparticle systems has received special attention during the past two decades. Polymeric microparticles (MPs) are acknowledged as very prevalent carriers toward an enhanced bio-distribution and bioavailability of both hydrophilic and lipophilic drug substances. Poly(lactic acid) (PLA), poly(lactic-co-glycolic acid) (PLGA), and their copolymers are among the most frequently used biodegradable polymers for encapsulated drugs. This review describes the current state-of-the-art research in the study of poly(lactic acid)/poly(lactic-co-glycolic acid) microparticles and PLA-copolymers with other aliphatic acids as drug delivery devices for increasing the efficiency of drug delivery, enhancing the release profile, and drug targeting of active pharmaceutical ingredients (API). Potential advances in generics and the constant discovery of therapeutic peptides will hopefully promote the success of microsphere technology.

Gelatin nanoparticles via template polymerization for drug delivery system to photoprocess application in cells

Photodynamic therapy (PDT) is a clinical treatment based on the activation of light-absorbing photosensitizers (PS) to generate reactive oxygen species, which are toxic to the targeted disease cells. Because most PS are hydrophobic with poor water solubility, it is necessary to encapsulate and solubilize PS in aqueous conditions to improve the photodynamic action for this compound. In this work, gelatin-poly(acrylic acid) nanoparticles (PAA/gelatin nanoparticles) via template polymerization for incorporation aluminum chloride phthalocyanine (ClAlPc) as a model drug for PDT application were developed. Biocompatible core-shell polymeric nanoparticles were fabricated via template polymerization using gelatin and acrylic acid as a reaction system. The nanoparticulate system was studied by scanning electron microscopy, steady-state, and their biological activity was evaluated using in vitro cancer cell lines by classical MTT assay. The obtained nanoparticles had a spherical shape and DLS particle size were determined further and was found to be around 170 nm. The phthalocyanine-loaded-nanoparticles maintained their photophysical behaviour after encapsulation. It is found that ClAlPc can be released from the nanoparticles in a sustained manner with a small initial burst release. In vitro cytotoxicity revealed that ClAlPc-loaded nanoparticles had similar cytotoxicity to free ClAlPc with mouse melanoma cancer cell line (B16-F10). In vitro photoeffects assay indicated that the nanoparticle formulation was superior in anticancer effect to free ClAlPc on mouse melanoma cancer cell line B16-F10. The results indicate that ClAlPc encapsulated in gelatin-poly(acrylic acid) nanoparticles are a successful delivery system for improving photodynamic activity in the target tissue.

Gelation and yielding behavior of polymer–nanoparticle hydrogels

Polymer–nanoparticle hydrogels are a unique class of self‐assembled, shear‐thinning, yield‐stress fluids that have demonstrated potential utility in many impactful applications. Here, we present a thorough analysis of the gelation and yielding behavior of these materials with respect to the polymer and nanoparticle component stoichiometry. Through comprehensive rheological and diffusion studies, we reveal insights into the structural dynamics of the polymer nanoparticle network that identify that stoichiometry plays a key role in gelation and yielding, ultimately enabling the development of hydrogel formulations with unique shear‐thinning and yield‐stress behaviors. Access to these materials opens new doors for interesting applications in a variety of fields including tissue engineering, drug delivery, and controlled solution viscosity.

Combining Active Carbonic Anhydrase with Nanogels: Enzyme Protection and Zinc Sensing

Background

Due to its excellent biocompatibility, the polyacrylamide (PAAm) hydrogel has shown great potential for the immobilization of enzymes used in biomedical applications. The major challenge involved is to preserve, during the immobilization process, both the biological activity and the structural integrity of the enzymes. Here we report, for the first time, a proof-of-concept study for embedding active carbonic anhydrase (CA) into polyacrylamide (PAAm) nanogels. By immobilizing CA in these nanogels, we hope to provide important advantages, such as matrix protection of the CA as well as its targeted delivery, and also for potentially using these nanogels as zinc nano-biosensors, both in-vitro and in-vivo.

Methods and Results

Two methods are reported here for CA immobilization: encapsulation and surface conjugation. In the encapsulation method, the common process was improved, so as to best preserve the CA, by 1) using a novel biofriendly nonionic surfactant system (Span 80/Tween 80/Brij 30) and 2) using an Al₂O₃ adsorptive filtration purification procedure. In the surface conjugation method, blank PAAm nanogels were activated by N-hydroxysuccinimide and the CA was cross-linked to the nanogels. The amount of active CA immobilized in the nanoparticles was quantified for both methods. Per 1 g nanogels, the CA encapsulated nanogels contain 11.3 mg active CA, while the CA conjugated nanogels contain 22.5 mg active CA. Also, the CA conjugated nanoparticles successfully measured free Zn²⁺ levels in solution, with the Zn²⁺ dissociation constant determined to be 9 pM.

Conclusion

This work demonstrates universal methods for immobilizing highly fragile bio-macromolecules inside nanoparticle carriers, while preserving their structural integrity and biological activity. The advantages and limitations are discussed, as well as the potential biomedical applications.

Machine learning directed drug formulation development

Machine learning (ML) has enabled ground-breaking advances in the healthcare and pharmaceutical sectors, from improvements in cancer diagnosis, to the identification of novel drugs and drug targets as well as protein structure prediction. Drug formulation is an essential stage in the discovery and development of new medicines. Through the design of drug formulations, pharmaceutical scientists can engineer important properties of new medicines, such as improved bioavailability and targeted delivery. The traditional approach to drug formulation development relies on iterative trial-and-error, requiring a large number of resource-intensive and time-consuming in vitro and in vivo experiments. This review introduces the basic concepts of ML-directed workflows and discusses how these tools can be used to aid in the development of various types of drug formulations. ML-directed drug formulation development offers unparalleled opportunities to fast-track development efforts, uncover new materials, innovative formulations, and generate new knowledge in drug formulation science. The review also highlights the latest artificial intelligence (AI) technologies, such as generative models, Bayesian deep learning, reinforcement learning, and self-driving laboratories, which have been gaining momentum in drug discovery and chemistry and have potential in drug formulation development.

Particle engineering principles and technologies for pharmaceutical biologics

The global market of pharmaceutical biologics has expanded significantly during the last few decades. Currently, pharmaceutical biologic products constitute an indispensable part of the modern medicines. Most pharmaceutical biologic products are injections either in the forms of solutions or lyophilized powders because of their low oral bioavailability. There are certain pharmaceutical biologic entities formulated into particulate delivery systems for the administration via non-invasive routes or to achieve prolonged pharmaceutical actions to reduce the frequency of injections. It has been well documented that the design of nano- and microparticles via various particle engineering technologies could render pharmaceutical biologics with certain benefits including improved stability, enhanced intracellular uptake, prolonged pharmacological effect, enhanced bioavailability, reduced side effects, and improved patient compliance. Herein, we review the principles of the particle engineering technologies based on bottom-up approach and present the important formulation and process parameters that influence the critical quality attributes with some mathematical models. Subsequently, various nano- and microparticle engineering technologies used to formulate or process pharmaceutical biologic entities are reviewed. Lastly, an array of commercialized products of pharmaceutical biologics accomplished based on various particle engineering technologies are presented and the challenges in the development of particulate delivery systems for pharmaceutical biologics are discussed.

The next generation of HCV vaccines: a focus on novel adjuvant development

INTRODUCTION

Considerable efforts have been made to treat and prevent acute and chronic infections caused by the hepatitis C virus (HCV). Current treatments are unable to protect people from reinfection. Hence, there is a need for development of both preventive and therapeutic HCV vaccines. Many vaccine candidates are in development to fight against HCV, but their efficacy has so far proven limited partly due to low immunogenicity.

AREAS COVERED

We explore development of novel and powerful adjuvants to achieve an effective HCV vaccine. The basis for developing strong adjuvants is to understand the innate immunity pathway, which subsequently stimulates humoral and cellular immune responses. We have also investigated immunogenicity of developed adjuvants that have been used in recent studies available in online databases such as PubMed, PMC, ScienceDirect, Google Scholar, etc.

EXPERT OPINION

Adjuvants are used as a part of vaccine formulation to boost vaccine immunogenicity and antigen delivery. Several FDA-approved adjuvants are used in licensed human vaccines. Unfortunately, no adjuvant has yet been proven to boost HCV immune responses to the extent needed for an effective vaccine. One of the promising approaches for developing an effective adjuvant is the combination of various adjuvants to trigger several innate immune responses, leading to activation of adaptive immunity.[Figure: see text].

A Collagen-Mimetic Organic-Inorganic Hydrogel for Cartilage Engineering

Promising strategies for cartilage regeneration rely on the encapsulation of mesenchymal stromal cells (MSCs) in a hydrogel followed by an injection into the injured joint. Preclinical and clinical data using MSCs embedded in a collagen gel have demonstrated improvements in patients with focal lesions and osteoarthritis. However, an improvement is often observed in the short or medium term due to the loss of the chondrocyte capacity to produce the correct extracellular matrix and to respond to mechanical stimulation. Developing novel biomimetic materials with better chondroconductive and mechanical properties is still a challenge for cartilage engineering. Herein, we have designed a biomimetic chemical hydrogel based on silylated collagen-mimetic synthetic peptides having the ability to encapsulate MSCs using a biorthogonal sol-gel cross-linking reaction. By tuning the hydrogel composition using both mono- and bi-functional peptides, we succeeded in improving its mechanical properties, yielding a more elastic scaffold and achieving the survival of embedded MSCs for 21 days as well as the up-regulation of chondrocyte markers. This biomimetic long-standing hybrid hydrogel is of interest as a synthetic and modular scaffold for cartilage tissue engineering.

Enhancing subcutaneous injection and target tissue accumulation of nanoparticles via co-administration with macropinocytosis inhibitory nanoparticles (MiNP)

A significant barrier to the application of nanoparticles for precision medicine is the mononuclear phagocyte system (MPS), a diverse population of phagocytic cells primarily located within the liver, spleen and lymph nodes. The majority of nanoparticles are indiscriminately cleared by the MPS via macropinocytosis before reaching their intended targets, resulting in side effects and decreased efficacy. Here, we demonstrate that the biodistribution and desired tissue accumulation of targeted nanoparticles can be significantly enhanced by co-injection with polymeric micelles containing the actin depolymerizing agent latrunculin A. These macropinocytosis inhibitory nanoparticles (MiNP) were found to selectively inhibit non-specific uptake of a second "effector" nanoparticle in vitro without impeding receptor-mediated endocytosis. In tumor bearing mice, co-injection with MiNP in a single multi-nanoparticle formulation significantly increased the accumulation of folate-receptor targeted nanoparticles within tumors. Furthermore, subcutaneous co-administration with MiNP allowed effector nanoparticles to achieve serum levels that rivaled a standard intravenous injection. This effect was only observed if the effector nanoparticles were injected within 24 h following MiNP administration, indicating a temporary avoidance of MPS cells. Co-injection with MiNP therefore allows reversible evasion of the MPS for targeted nanoparticles and presents a previously unexplored method of modulating and improving nanoparticle biodistribution following subcutaneous administration.

Poroelastic shape relaxation of hydrogel particles

Hydrogels are commonly used in research and energy, manufacturing, agriculture, and biomedical applications. These uses typically require hydrogel mechanics and internal water transport, described by the poroelastic diffusion coefficient, to be characterized. Sophisticated indentation-based approaches are typically used for this purpose, but they require expensive instrumentation and are often limited to planar samples. Here, we present Shape Relaxation (SHARE), an alternative way to assess the poroelastic diffusion coefficient of hydrogel particles that is cost-effective, straightforward, and versatile. This approach relies on first indenting a hydrogel particle via swelling within a granular packing, and then monitoring how the indented shape of the hydrogel relaxes after it is removed from the packing. We validate this approach using experiments in packings with varying grain sizes and confining stresses; these yield measurements of the poroelastic diffusion coefficient of polyacrylamide hydrogels that are in good agreement with those previously obtained using indentation approaches. We therefore anticipate that the SHARE approach will find broad use in a range of applications of hydrogels and other swellable soft materials.

Sustained release of peptides and proteins from polymeric nanocarriers produced by inverse Flash NanoPrecipitation

Peptide and protein therapeutics generally exhibit high potency and specificity and are increasingly important segments of the pharmaceutical market. However, their clinical applications are limited by rapid clearance and poor membrane permeability. Encapsulation of the peptide or protein into a nano-scale carrier can modify its pharmacokinetics and biodistribution. This might be employed to promote uptake in desired cell types or tissues, to limit systemic exposure, or to reduce the need for frequent injections. We have recently described inverse Flash NanoPrecipitation (iFNP), a scalable technique to encapsulate water-soluble therapeutics into polymeric nanocarriers, and have demonstrated improvements in therapeutic loading of an order of magnitude over comparable approaches. Here, we describe the formulation parameters that control release rates of encapsulated model therapeutics polymyxin B, lysozyme, and bovine serum albumin from nanocarriers produced using iFNP. Using a neutropenic lung infection mouse model with a multi-drug resistant Acinetobacter baumannii clinical isolate, we demonstrate enhanced therapeutic effect and safety profile afforded by nanocarrier-encapsulated polymyxin B following pulmonary administration. The encapsulated formulation reduced toxicity observed at elevated doses and resulted in up to 2.7-log₁₀ reduction in bacterial burden below that of unencapsulated polymyxin B. These results establish the promise of iFNP as a platform for nanocarrier delivery of water-soluble therapeutics.

NGF nanoparticles enhance the potency of transplanted human umbilical cord mesenchymal stem cells for myocardial repair

In this study, we investigated whether human umbilical cord mesenchymal stem cell (hUCMSC) fibrin patches loaded with nerve growth factor (NGF) poly(lactic-co-glycolic acid) (PLGA) nanoparticles could enhance the therapeutic potency of hUCMSCs for myocardial infarction (MI). In vitro, NGF significantly improved the proliferation of hUCMSCs and mitigated cytotoxicity and apoptosis under hypoxic injury. NGF also promoted the paracrine effects of hUCMSCs on angiogenesis and cardiomyocyte protection. The tyrosine kinase A (TrkA) and phosphoinositide 3-kinase (PI3K)-serine/threonine protein kinase (Akt) signaling pathways in hUCMSCs were involved in the NGF-induced protection. NGF PLGA nanoparticles continued to release NGF for at least 1 mo and also exerted a protective effect on hUCMSCs, the same with free NGF. In vivo, we treated MI mice with nothing (MI group), a cell-free fibrin patch with blank PLGA nanoparticles (MI + OP group), a cell-free fibrin patch with NGF nanoparticles (MI + NGF group), and hUCMSC fibrin patches with blank PLGA nanoparticles (MI + MSC group) or NGF PLGA nanoparticles (MSC + NGF group). Among these groups, the MSC + NGF group exhibited the best cardiac contractile function, the smallest infarct size, and the thickest ventricular wall. The application of NGF PLGA nanoparticles significantly improved the retention of transplanted hUCMSCs and enhanced their ability to reduce myocardial apoptosis and promote angiogenesis in the mouse heart after MI. These findings demonstrate the promising therapeutic potential of hUCMSC fibrin cardiac patches loaded with NGF PLGA nanoparticles.NEW & NOTEWORTHY NGF PLGA nanoparticles can exert a protective effect on hUCMSCs and promote the paracrine effects of hUCMSCs on angiogenesis and cardiomyocyte protection through TrkA-PI3K/Akt signaling pathway, the same with free NGF. The application of NGF PLGA nanoparticles in the hUCMSC fibrin cardiac patches can significantly improve the retention of transplanted hUCMSCs and enhance their ability to reduce myocardial apoptosis and promote angiogenesis in the mouse heart after MI.

The Role of Nanomaterials in Stroke Treatment: Targeting Oxidative Stress

Stroke has a high rate of morbidity and disability, which seriously endangers human health. In stroke, oxidative stress leads to further damage to the brain tissue. Therefore, treatment for oxidative stress is urgently needed. However, antioxidative drugs have demonstrated obvious protective effects in preclinical studies, but the clinical studies have not seen breakthroughs. Nanomaterials, with their characteristically small size, can be used to deliver drugs and have demonstrated excellent performance in treating various diseases. Additionally, some nanomaterials have shown potential in scavenging reactive oxygen species (ROS) in stroke according to the nature of nanomaterials. The drugs' delivery ability of nanomaterials has great significance for the clinical translation and application of antioxidants. It increases drug blood concentration and half-life and targets the ischemic brain to protect cells from oxidative stress-induced death. This review summarizes the characteristics and progress of nanomaterials in the application of antioxidant therapy in stroke, including ischemic stroke, hemorrhagic stroke, and neural regeneration. We also discuss the prospect of nanomaterials for the treatment of oxidative stress in stroke and the challenges in their application, such as the toxicity and the off-target effects of nanomaterials.

A pulsatile release platform based on photo-induced imine-crosslinking hydrogel promotes scarless wound healing

Effective healing of skin wounds is essential for our survival. Although skin has strong regenerative potential, dysfunctional and disfiguring scars can result from aberrant wound repair. Skin scarring involves excessive deposition and misalignment of ECM (extracellular matrix), increased cellularity, and chronic inflammation. Transforming growth factor-β (TGFβ) signaling exerts pleiotropic effects on wound healing by regulating cell proliferation, migration, ECM production, and the immune response. Although blocking TGFβ signaling can reduce tissue fibrosis and scarring, systemic inhibition of TGFβ can lead to significant side effects and inhibit wound re-epithelization. In this study, we develop a wound dressing material based on an integrated photo-crosslinking strategy and a microcapsule platform with pulsatile release of TGF-β inhibitor to achieve spatiotemporal specificity for skin wounds. The material enhances skin wound closure while effectively suppressing scar formation in murine skin wounds and large animal preclinical models. Our study presents a strategy for scarless wound repair.

Dysfunctional and disfiguring scars can result from aberrant wound repair. Here, the authors develop a wound dressing material based on an integrated photo-crosslinking strategy and a microcapsule platform with pulsatile release of TGF-β inhibitor to achieve spatiotemporal specificity for scarless wound repair.

Highly-loaded protein nanocarriers prepared by Flash NanoPrecipitation with hydrophobic ion pairing

The efficient encapsulation of therapeutic proteins into delivery vehicles, particularly without loss of function, remains a significant research hurdle. Typical liposomal formulations achieve drug loadings on the order of 3-5% and encapsulation efficiencies around 50%. We demonstrate the encapsulation of model proteins with isoelectric points above and below pH 7 into nanocarriers (NCs) with protein loadings as high as 46% and encapsulation efficiencies above 95%. This is done by combining the continuous nanofabrication process Flash NanoPrecipitation (FNP) with the technique of hydrophobic ion pairing by forming and encapsulating an ionic complex within a nanocarrier stabilized by a block copolymer surface layer. We complex and encapsulate lysozyme with two anionic hydrophobic counterions, sodium oleate and sodium dodecyl sulfate, using either a pre-formed complex or in situ pairing. The strategy successfully forms NCs ~150 nm in diameter and achieves encapsulation efficiencies over 95%. Protein release rate from the NCs in physiological conditions and the bioactivity of released lysozyme are measured, and both are found to vary with the complexing counterion and the protein/counterion ratio used during formulation. Protein release on the time scale of weeks is observed, and up to 100% bioactivity is measured from released lysozyme. 16 quaternary ammonium cationic counterions are tested to encapsulate ovalbumin in 32 formulations. Of these, 19 successfully form ~150 nm NCs with loadings up to 29% and encapsulation efficiencies up to 88%. We divide the formulations into four regimes and identify chemical factors responsible for the success or failure of a given counterion to formulate NCs with the desirable size, loading, and encapsulation efficiency. A successful ovalbumin NC formulation was then tested in vivo in a mouse nasal vaccine model and found to induce a higher titer of OVA-specific IgG than unencapsulated ovalbumin. Taken together, these findings suggest that Flash NanoPrecipitation with hydrophobic ion pairing is an attractive platform for encapsulating high molecular weight proteins into NCs. In particular, the ability to tune protein release rate by varying the counterion or protein/counterion ratio used during formulation is a useful feature.

In vitro Study on Synergistic Interactions Between Free and Encapsulated Q-Griffithsin and Antiretrovirals Against HIV-1 Infection

Introduction

Human immunodeficiency virus (HIV) remains a persistent global challenge, impacting 38 million people worldwide. Antiretrovirals (ARVs) including tenofovir (TFV), raltegravir (RAL), and dapivirine (DAP) have been developed to prevent and treat HIV-1 via different mechanisms of action. In parallel, a promising biological candidate, griffithsin (GRFT), has demonstrated outstanding preclinical safety and potency against HIV-1. While ARV co-administration has been shown to enhance virus inhibition, synergistic interactions between ARVs and the oxidation-resistant variant of GRFT (Q-GRFT) have not yet been explored. Here, we co-administered Q-GRFT with TFV, RAL, and DAP, in free and encapsulated forms, to identify unique protein-drug synergies.

Methods

Nanoparticles (NPs) were synthesized using a single or double-emulsion technique and release from each formulation was assessed in simulated vaginal fluid. Next, each ARV, in free and encapsulated forms, was co-administered with Q-GRFT or Q-GRFT NPs to evaluate the impact of co-administration in HIV-1 pseudovirus assays, and the combination indices were calculated to identify synergistic interactions. Using the most synergistic formulations, we investigated the effect of agent incorporation in NP-fiber composites on release properties. Finally, NP safety was assessed in vitro using MTT assay.

Results

All active agents were encapsulated in NPs with desirable encapsulation efficiency (15–100%), providing ~20% release over 2 weeks. The co-administration of free Q-GRFT with each free ARV resulted in strong synergistic interactions, relative to each agent alone. Similarly, Q-GRFT NP and ARV NP co-administration resulted in synergy across all formulations, with the most potent interactions between encapsulated Q-GRFT and DAP. Furthermore, the incorporation of Q-GRFT and DAP in NP-fiber composites resulted in burst release of DAP and Q-GRFT with a second phase of Q-GRFT release. Finally, all NP formulations exhibited safety in vitro.

Conclusions

This work suggests that Q-GRFT and ARV co-administration in free or encapsulated forms may improve efficacy in achieving prophylaxis.

Biodegradable Polymeric Nanoparticles for Drug Delivery to Solid Tumors

Advances in nanotechnology have favored the development of novel colloidal formulations able to modulate the pharmacological and biopharmaceutical properties of drugs. The peculiar physico-chemical and technological properties of nanomaterial-based therapeutics have allowed for several successful applications in the treatment of cancer. The size, shape, charge and patterning of nanoscale therapeutic molecules are parameters that need to be investigated and modulated in order to promote and optimize cell and tissue interaction. In this review, the use of polymeric nanoparticles as drug delivery systems of anticancer compounds, their physico-chemical properties and their ability to be efficiently localized in specific tumor tissues have been described. The nanoencapsulation of antitumor active compounds in polymeric systems is a promising approach to improve the efficacy of various tumor treatments.

Stability of Protein Structure during Nanocarrier Encapsulation: Insights on Solvent Effects from Simulations and Spectroscopic Analysis

The dosing of peptide and protein therapeutics is complicated by rapid clearance from the blood pool and poor cellular membrane permeability. Encapsulation into nanocarriers such as liposomes or polymersomes has long been explored to overcome these limitations, but manufacturing challenges have limited clinical translation by these approaches. Recently, inverse Flash NanoPrecipitation (iFNP) has been developed to produce highly loaded polymeric nanocarriers with the peptide or protein contained within a hydrophilic core, stabilized by a hydrophobic polymer shell. Encapsulation of proteins with higher-order structure requires understanding how processing may affect their conformational state. We demonstrate a combined experimental/simulation approach to characterize protein behavior during iFNP processing steps using the Trp-cage protein TC5b as a model. Explicit-solvent fully atomistic molecular dynamics simulations with enhanced sampling techniques are coupled with two-dimensional heteronuclear multiple-quantum coherence nuclear magnetic resonance spectroscopy (2D-HMQC NMR) and circular dichroism to determine the structure of TC5b during mixed-solvent exposure encountered in iFNP processing. The simulations involve atomistic models of mixed solvents and protein to capture the complexity of the hydrogen bonding and hydrophobic interactions between water, dimethylsulfoxide (DMSO), and the protein. The combined analyses reveal structural unfolding of the protein in 11 M DMSO but confirm complete refolding after release from the polymeric nanocarrier back into an aqueous phase. These results highlight the insights that simulations and NMR provide for the formulation of proteins in nanocarriers.

Resveratrol: nanocarrier-based delivery systems to enhance its therapeutic potential

Resveratrol (3,5,4'-trihydroxystilbene) is a polyphenolic compound existing in trees, peanuts and grapes and exhibits a broad spectrum of promising therapeutic activities, but it is unclear whether this entity targets the sites of action after oral administration. In vivo applicability of resveratrol has limited success so far, mainly due to its incompetent systemic delivery resulting from its low water solubility, poor bioavailability and short biological half-life. First-pass metabolism and presence of enterohepatic recirculation create doubt on the biological application of high doses typically used for in vitro trials. To augment bioavailability, absorption and uptake of resveratrol by cellular internalization, countless approaches have been implemented which involve the use of nanocarriers. Nanocarriers are a well-known delivery system used to reduce first-pass hepatic metabolism, overcome enterohepatic recirculation and accelerate the absorption of drugs via lymphatic pathways.

Particle Formation Mechanisms in the Nanoprecipitation of Polystyrene

Numerous precipitation methods for creating nanoparticle dispersions that are based on mixing a solution with a miscible nonsolvent have been developed. Here, we show that for polymer particles, the formation is highly dependent on the rate of mixing. We also demonstrate the importance of the glass transition of the polymers on particle formation. A simple model of droplet formation during mixing provides a satisfactory description of the observed dependence of particle size on polymer molecular weight, concentration, solvent ratio, and mixing conditions.

Injectable Hydrogels for Sustained Codelivery of Subunit Vaccines Enhance Humoral Immunity

Vaccines aim to elicit a robust, yet targeted, immune response. Failure of a vaccine to elicit such a response arises in part from inappropriate temporal control over antigen and adjuvant presentation to the immune system. In this work, we sought to exploit the immune system's natural response to extended pathogen exposure during infection by designing an easily administered slow-delivery vaccine platform. We utilized an injectable and self-healing polymer-nanoparticle (PNP) hydrogel platform to prolong the codelivery of vaccine components to the immune system. We demonstrated that these hydrogels exhibit unique delivery characteristics, whereby physicochemically distinct compounds (such as antigen and adjuvant) could be codelivered over the course of weeks. When administered in mice, hydrogel-based sustained vaccine exposure enhanced the magnitude, duration, and quality of the humoral immune response compared to standard PBS bolus administration of the same model vaccine. We report that the creation of a local inflammatory niche within the hydrogel, coupled with sustained exposure of vaccine cargo, enhanced the magnitude and duration of germinal center responses in the lymph nodes. This strengthened germinal center response promoted greater antibody affinity maturation, resulting in a more than 1000-fold increase in antigen-specific antibody affinity in comparison to bolus immunization. In summary, this work introduces a simple and effective vaccine delivery platform that increases the potency and durability of subunit vaccines.

Comparative Encapsulation Efficiency of Lutein in Micelles Synthesized via Batch and High Throughput Methods

PURPOSE

Black raspberries (BRBs) and their anthocyanin-rich hydrophilic fractions (BRB-H) have exhibited significant chemopreventative activity across aerodigestive cancers. Lutein, the primary component of the BRB lipophilic fraction (BRB-L), also demonstrates bioactivity potential, but is less well characterized, in part because of its poor, innate bioavailability. For these lipophilic compounds to be accurately evaluated for anticancer efficacy, it is necessary to increase their functional bioavailability using delivery vehicles. Lutein has been delivered in commercial settings in emulsion form. However, emulsions are unstable, particularly in the gastrointestinal tract, which limit their use as an oral nutraceutical. Here, we evaluated lutein encapsulation and cellular uptake for nanoparticle (NP) delivery vehicles composed of three different materials synthesized via two different approaches.

METHODS

Specifically, NPs were synthesized via smaller scale batch interfacial instability (II) sonication and semi-continuous high throughput electrohydrodynamic-mediated mixing nanoprecipitation (EM-NP) methods using polystyrene-polyethylene oxide (PSPEO) or polycaprolactone-polyethylene glycol (PCLPEG) block copolymers and PHOSPHOLIPON 90G® (P90G, Lipoid GmbH) lipids. Size distribution, lutein encapsulation efficiency (EE), and cellular uptake and delivery were evaluated for each NP formulation.

RESULTS

NPs produced via high throughput EM-NP had higher EEs than NPs produced via batch II sonication, and P90G had the greatest EE (55%) and elicited faster cellular uptake in premalignant oral epithelial cells (SCC83) compared to other delivery systems.

CONCLUSION

These qualities suggest P90G could be a beneficial candidate for future lutein in vitro delivery research and clinical translation for oral cancer prevention.

Challenging development of storable particles for oral delivery of a physiological nitric oxide donor

Nitric oxide (NO) deficiency is often associated with several acute and chronic diseases. NO donors and especially S-nitrosothiols such as S-nitrosoglutathione (GSNO) have been identified as promising therapeutic agents. Although their permeability through the intestinal barrier have recently be proved, suitable drug delivery systems have to be designed for their oral administration. This is especially challenging due to the physico-chemical features of these drugs: high hydrophilicity and high lability. In this paper, three types of particles were prepared with an Eudragit® polymer: nanoparticles and microparticles obtained with a water-in-oil-in-water emulsion/evaporation process versus microparticles obtained with a solid-in-oil-in-water emulsion/evaporation process. They had a similar encapsulation efficiency (around 30%), and could be freeze-dried then be stored at least one month without modification of their critical attributes (size and GSNO content). However, microparticles had a slightly slower in vitro release of GSNO than nanoparticles, and were able to boost by a factor of two the drug intestinal permeability (Caco-2 model). Altogether, this study brings new data about GSNO intestinal permeability and three ready-to-use formulations suitable for further preclinical studies with oral administration.

Poroelastic properties of hydrogel microparticles

Hydrogels can be formed in a number of different geometries depending upon desired function. However, due to the lack of appropriate models required to interpret experimental data, it remains unclear whether hydrogel microparticles have the same poroelastic properties as hydrogel films made with the same components. We perform numerical simulations to determine the universal force relaxation of a poroelastic hydrogel particle undergoing constant compression by a spherical probe, allowing analysis of experimental measurements of hydrogel particle material properties for the first time. In addition, we perform experimental measurements, using colloidal probe atomic force microscopy, of the force relaxation of polyacrylamide films and particles made with identical monomer and cross-linker concentrations. We fit our universal curve to the experimental data in order to extract material properties including shear modulus, Poisson's ratio and solvent diffusivity. Good agreement is found for the shear modulus and Poisson's ratio between the particles and the films. In contrast, the diffusivity of the polyacrylamide particles was found to be about half that of the films, suggesting that differences in the synthesis and homogeneity of the films and the particles play a role in determining transport and subsequent release of molecules in hydrogel particles.

Delivery strategies for macromolecular drugs in cancer therapy

With the development of biotherapy, biomacromolecular drugs have gained tremendous attention recently, especially in drug development field due to the sophisticated functions in vivo. Over the past few years, a motley variety of drug delivery strategies have been developed for biomacromolecular drugs to overcome the difficulties in the druggability, e.g., the instability and easily restricted by physiologic barriers. The application of novel delivery systems to deliver biomacromolecular drugs can usually prolong the half-life, increase the bioavailability, or improve patient compliance, which greatly improves the efficacy and potentiality for clinical use of biomacromolecular drugs. In this review, recent studies regarding the drug delivery strategies for macromolecular drugs in cancer therapy are summarized, mainly drawing on the development over the last five years.

Quality by design thinking in the development of long-acting injectable PLGA/PLA-based microspheres for peptide and protein drug delivery

Adopting the Quality by Design (QbD) approach in the drug development process has transformed from "nice-to-do" into a crucial and required part of the development, ensuring the quality of pharmaceutical products throughout their whole life cycles. This review is discussing the implementation of the QbD thinking into the production of long-acting injectable (LAI) PLGA/PLA-based microspheres for the therapeutic peptide and protein drug delivery. Various key elements of the QbD approaches are initially elaborated using Bydureon®, a commercial product of LAI PLGA/PLA-based microspheres, as a classical example. Subsequently, the factors influencing the release patterns and the stability of the peptide and protein drugs are discussed. This is followed by a summary of the state-of-the-art of manufacturing LAI PLGA/PLA-based microspheres and the related critical process parameters (CPPs). Finally, a landscape of generic product development of LAI PLGA/PLA-based microspheres is reviewed including some major challenges in the field.

Modulation of protein release from penta-block copolymer microspheres

Releasing a protein according to a zero-order profile without protein denaturation during the polymeric microparticle degradation process is very challenging. The aim of the current study was to develop protein-loaded microspheres with new PLGA based penta-block copolymers for a linear sustained protein release. Lysozyme was chosen as model protein and 40 µm microspheres were prepared using the solid-in-oil-in-water solvent extraction/evaporation process. Two types of PLGA-P188-PLGA penta-block copolymers were synthetized with two PLGA-segments molecular weight (20 kDa or 40 kDa). The resulting microspheres (50P20-MS and 50P40-MS) had the same size, an encapsulation efficiency around 50-60% but different porosities. Their protein release profiles were complementary: linear but non complete for 50P40-MS, non linear but complete for 50P20-MS. Two strategies, polymer blending and microsphere mixing, were considered to match the release to the desired profile. The (1:1) microsphere mixture was successful. It induced a bi-phasic release with a moderate initial burst (around 13%) followed by a nearly complete linear release for 8 weeks. This study highlighted the potential of this penta-block polymer where the PEO block mass ratio influence clearly the Tg and consequently the microsphere structure and the release behavior at 37 °C. The (1:1) mixture was a starting point but could be finely tuned to control the protein release.