Biodistribution properties of nanoparticles based on mixtures of PLGA with PLGA–PEG diblock copolymers

Amphiphilic Block Copolymer Nanostructures as a Tunable Delivery Platform: Perspective and Framework for the Future Drug Product Development

Nanoformulation of active payloads or pharmaceutical ingredients (APIs) has always been an area of interest to achieve targeted, sustained, and efficacious delivery. Various delivery platforms have been explored, but loading and delivery of APIs have been challenging because of the chemical and structural properties of these molecules. Polymersomes made from amphiphilic block copolymers (ABCPs) have shown enormous promise as a tunable API delivery platform and confer multifold advantages over lipid-based systems. For example, a COVID booster vaccine comprising polymersomes encapsulating spike protein (ACM-001) has recently completed a Phase I clinical trial and provides a case for developing safe drug products based on ABCP delivery platforms. However, several limitations need to be resolved before they can reach their full potential. In this Perspective, we would like to highlight such aspects requiring further development for translating an ABCP-based delivery platform from a proof of concept to a viable commercial product.

Evasion of opsonization of macromolecules using novel surface-modification and biological-camouflage-mediated techniques for next-generation drug delivery

Opsonization plays a pivotal role in hindering controlled drug release from nanoformulations due to macrophage-mediated nanoparticle destruction. While first and second-generation delivery systems, such as lipoplexes (50-150 nm) and quantum dots, hold immense potential in revolutionizing disease treatment through spatiotemporal controlled drug delivery, their therapeutic efficacy is restricted by the selective labeling of nanoparticles for uptake by reticuloendothelial system and mononuclear phagocyte system via various molecular forces, such as electrostatic, hydrophobic, and van der Waals bonds. This review article presents novel insights into surface-modification techniques utilizing macromolecule-mediated approaches, including PEGylation, di-block copolymerization, and multi-block polymerization. These techniques induce stealth properties by generating steric forces to repel micromolecular-opsonins, such as fibrinogen, thereby mitigating opsonization effects. Moreover, advanced biological methods, like cellular hitchhiking and dysopsonic protein adsorption, are highlighted for their potential to induce biological camouflage by adsorbing onto the nanoparticulate surface, leading to immune escape. These significant findings pave the way for the development of long-circulating next-generation nanoplatforms capable of delivering superior therapy to patients. Future integration of artificial intelligence-based algorithms, integrated with nanoparticle properties such as shape, size, and surface chemistry, can aid in elucidating nanoparticulate-surface morphology and predicting interactions with the immune system, providing valuable insights into the probable path of opsonization.

In-vivo time course of organ uptake and blood-brain-barrier permeation of poly(L-lactide) and poly(perfluorodecyl acrylate) nanoparticles with different surface properties in unharmed and brain-traumatized rats

Background

Traumatic brain injury (TBI) has a dramatic impact on mortality and quality of life and the development of effective treatment strategies is of great socio-economic relevance. A growing interest exists in using polymeric nanoparticles (NPs) as carriers across the blood-brain barrier (BBB) for potentially effective drugs in TBI. However, the effect of NP material and type of surfactant on their distribution within organs, the amount of the administrated dose that reaches the brain parenchyma in areas with intact and opened BBB after trauma, and a possible elicited inflammatory response are still to be clarified.

Methods

The organ distribution, BBB permeation and eventual inflammatory activation of polysorbate-80 (Tw80) and sodiumdodecylsulfate (SDS) stabilized poly(L-lactide) (PLLA) and poly(perfluorodecyl acrylate) (PFDL) nanoparticles were evaluated in rats after intravenous administration. The NP uptake into the brain was assessed under intact conditions and after controlled cortical impact (CCI).

Results

A significantly higher NP uptake at 4 and 24 h after injection was observed in the liver and spleen, followed by the brain and kidney, with minimal concentrations in the lungs and heart for all NPs. A significant increase of NP uptake at 4 and 24 h after CCI was observed within the traumatized hemisphere, especially in the perilesional area, but NPs were still found in areas away from the injury site and the contralateral hemisphere. NPs were internalized in brain capillary endothelial cells, neurons, astrocytes, and microglia. Immunohistochemical staining against GFAP, Iba1, TNFα, and IL1β demonstrated no glial activation or neuroinflammatory changes.

Conclusions

Tw80 and SDS coated biodegradable PLLA and non-biodegradable PFDL NPs reach the brain parenchyma with and without compromised BBB by TBI, even though a high amount of NPs are retained in the liver and spleen. No inflammatory reaction is elicited by these NPs within 24 h after injection. Thus, these NPs could be considered as potentially effective carriers or markers of newly developed drugs with low or even no BBB permeation.

Tetracycline-grafted mPEG-PLGA micelles for bone-targeting and osteoporotic improvement

Aim: We aimed to create a nano drug delivery system with tetracycline (TC)-grafted methoxy poly-(ethylene-glycol)‒poly-(D, L-lactic-co-glycolic acid) (mPEG‒PLGA) micelles (TC‒mPEG‒PLGA) with TC and mPEG‒PLGA for potential bone targeting. Prospectively, TC‒mPEG‒PLGA aims to deliver bioactive compounds, such as astragaloside IV (AS), for osteoporotic therapy.

Methods: Preparation and evaluation of TC‒mPEG‒PLGA were accomplished via nano-properties, cytotoxicity, uptake by MC3T3-E1 cells, ability of hydroxyapatite targeting and potential bone targeting in vivo, as well as pharmacodynamics in a rat model.

Results: The measured particle size of AS-loaded TC‒mPEG‒PLGA micelles was an average of 52.16 ± 2.44 nm, which exhibited a sustained release effect compared to that by free AS. The TC‒mPEG‒PLGA demonstrated low cytotoxicity and was easily taken by MC3T3-E1 cells. Through assaying of bone targeting in vitro and in vivo, we observed that TC‒mPEG‒PLGA could effectively increase AS accumulation in bone. A pharmacodynamics study in mice suggested potentially increased bone mineral density by AS-loaded TC‒mPEG‒PLGA in ovariectomized rats compared to that by free AS.

Conclusion: The nano drug delivery system (TC‒mPEG‒PLGA) could target bone in vitro and in vivo, wherein it may be used as a novel delivery method for the enhancement of therapeutic effects of drugs with osteoporotic activity.

Impact of PEGylation on an antibody-loaded nanoparticle-based drug delivery system for the treatment of inflammatory bowel disease

Nanoparticle-based oral drug delivery systems have the potential to target inflamed regions in the gastrointestinal tract by specifically accumulating at disrupted colonic epithelium. But, delivery of intact protein drugs at the targeted site is a major challenge due to the harsh gastrointestinal environment and the protective mucus layer. Biocompatible nanoparticles engineered to target the inflamed colonic tissue and efficiently penetrate the mucosal layer can provide a promising approach for orally delivering monoclonal antibodies to treat inflammatory bowel disease. The study aims to develop mucus-penetrating nanoparticles composed of poly(lactic-co-glycolic acid, PLGA) polymers with two different polyethylene glycol (PEG) chain lengths (2 kDa and 5kDa) to encapsulate monoclonal antibody against tumor necrosis factor-α (TNF-α). The impact of different PEG chain lengths on the efficacy of the nanosystems was evaluated in vitro, ex vivo, and in vivo. Both PLGA-PEG2k and PLGA-PEG5k nanoparticles successfully encapsulated the antibody and significantly reduced TNF-α secretion from activated macrophages and intestinal epithelial cells. However, only antibody-loaded PLGA-PEG2k nanoparticles were able to alleviate the experimental acute colitis in mice demonstrated by improved colon weight/length ratio, histological score, and reduced tissue-associated myeloperoxidase activity and expression of proinflammatory cytokine TNF-α levels compared with the control group. The results suggest that despite having no significant differences in the in vitro cell-based assays, PEG chain length has a significant impact on the in vivo performance of the mucus penetrating nanoparticles. Overall, PLGA-PEG2k nanoparticles were presented as a promising oral delivery system for targeted antibody delivery to treat inflammatory bowel disease. STATEMENT OF SIGNIFICANCE: There is an unmet therapeutic need for oral drug delivery systems for safe and effective antibody therapy of inflammatory bowel disease. Therefore, we have developed PEGylated PLGA-based nanoparticulate drug delivery systems for oral targeted delivery of anti-TNF-α antibody as a potential alternative treatment strategy. The PEG chain length did not affect encapsulation efficiency or interaction with mucin in vitro but resulted in differences in in vitro release profile and in vivo efficacy study. We demonstrated the superiority of anti-TNF-α mAb-PLGA-PEG2k over mAb-PLGA-PEG5k nanoparticles to effectively exhibit anti-inflammatory responses in an acute murine colitis model. These nanoparticle-based formulations may be adjusted to encapsulate other drugs that could be applied to a number of disorders at different mucosal surfaces.

Bioactive Synthetic Polymers

Synthetic polymers are omnipresent in society as textiles and packaging materials, in construction and medicine, among many other important applications. Alternatively, natural polymers play a crucial role in sustaining life and allowing organisms to adapt to their environments by performing key biological functions such as molecular recognition and transmission of genetic information. In general, the synthetic and natural polymer worlds are completely separated due to the inability for synthetic polymers to perform specific biological functions; in some cases, synthetic polymers cause uncontrolled and unwanted biological responses. However, owing to the advancement of synthetic polymerization techniques in recent years, new synthetic polymers have emerged that provide specific biological functions such as targeted molecular recognition of peptides, or present antiviral, anticancer, and antimicrobial activities. In this review, the emergence of this generation of bioactive synthetic polymers and their bioapplications are summarized. Finally, the future opportunities in this area are discussed.

A Novel Sustained Anti-Inflammatory Effect of Atorvastatin-Calcium PLGA Nanoparticles: In Vitro Optimization and In Vivo Evaluation

Atorvastatin Calcium (At-Ca) has pleiotropic effect as anti-inflammatory drug beside its main antihyperlipidemic action. Our study was conducted to modulate the anti-inflammatory effect of At-Ca to be efficiently sustained for longer time. Single oil-water emulsion solvent evaporation technique was used to fabricate At-Ca into polymeric nanoparticles (NPs). In vitro optimization survey was performed on Poly(lactide-co-glycolide) (PLGA) loaded with At-Ca regrading to particle size, polydispersity index (PDI), zeta potential, percent entrapment efficiency (% EE), surface morphology and in vitro release pattern. In vitro drug-polymers interactions were fully scanned using Fourier-Transform Infrared Spectroscopy (FTIR) and Differential Scanning calorimetry (DSC) proving that the method of fabrication is an optimal strategy maintaining the drug structure with no interaction with polymeric matrix. The optimized formula with particle size (248.2 ± 15.13 nm), PDI (0.126 ± 0.048), zeta potential (-12.41 ± 4.80 mV), % EE (87.63 ± 3.21%), initial burst (39.78 ± 6.74%) and percent cumulative release (83.63 ± 3.71%) was orally administered in Male Sprague-Dawley rats to study the sustained anti-inflammatory effect of At-Ca PLGA NPs after carrageenan induced inflammation. In vivo results demonstrate that AT-Ca NPs has a sustained effect extending for approximately three days. Additionally, the histological examination revealed that the epidermal/dermal layers restore their typical normal cellular alignment with healthy architecture.

Formulation and In Vitro Characterization of PLGA/PLGA-PEG Nanoparticles Loaded with Murine Granulocyte-Macrophage Colony-Stimulating Factor

Granulocyte-macrophage colony-stimulating factor (GM-CSF) has demonstrated notable clinical activity in cancer immunotherapy, but it is limited by systemic toxicities, poor bioavailability, rapid clearance, and instability in vivo. Nanoparticles (NPs) may overcome these limitations and provide a mechanism for passive targeting of tumors. This study aimed to develop GM-CSF-loaded PLGA/PLGA-PEG NPs and evaluate them in vitro as a potential candidate for in vivo administration. NPs were created by a phase-separation technique that did not require toxic/protein-denaturing solvents or harsh agitation techniques and encapsulated GM-CSF in a more stable precipitated form. NP sizes were within 200 nm for enhanced permeability and retention (EPR) effect with negative zeta potentials, spherical morphology, and high entrapment efficiencies. The optimal formulation was identified by sustained release of approximately 70% of loaded GM-CSF over 24 h, alongside an average size of 143 ± 35 nm and entrapment efficiency of 84 ± 5%. These NPs were successfully freeze-dried in 5% (w/v) hydroxypropyl-β-cyclodextrin for long-term storage and further characterized. Bioactivity of released GM-CSF was determined by observing GM-CSF receptor activation on murine monocytes and remained fully intact. NPs were not cytotoxic to murine bone marrow-derived macrophages (BMDMs) at concentrations up to 1 mg/mL as determined by MTT and trypan blue exclusion assays. Lastly, NP components generated no significant transcription of inflammation-regulating genes from BMDMs compared to IFNγ+LPS "M1" controls. This report lays the preliminary groundwork to validate in vivo studies with GM-CSF-loaded PLGA/PEG-PLGA NPs for tumor immunomodulation. Overall, these data suggest that in vivo delivery will be well tolerated.

Self-Encapsulation of Biomacromolecule Drugs in Porous Microscaffolds with Aqueous Two-Phase Systems

At present, the most commonly used methods of microencapsulation of protein drugs such as spray drying, multiple emulsification, and phase separation, can easily cause the problem of protein instability, which leads to low bioavailability and uncontrolled release of protein drugs. Herein, a novel method to encapsulate protein drugs into porous microscaffolds effectively and stably was described. Ammonium hydrogen carbonate (NH₄HCO₃) was employed to prepare porous microscaffolds. α-Amylase was encapsulated into the porous microscaffolds without denaturing conditions by an aqueous two-phase system (PEG/Sulfate). The pores were closed by heating above the glass transition temperature to achieve a sustained release of microscaffolds. The pore-closed microscaffolds were characterized and released in vitro. The integrity and activity of protein drugs were investigated to verify that this method was friendly to protein drugs. Results showed that the pores were successfully closed and a high loading amount of 9.67 ± 6.28% (w/w) was achieved. The pore-closed microscaffolds released more than two weeks without initial burst, and a high relative activity (92% compared with native one) of protein demonstrated the feasibility of this method for protein drug encapsulation and delivery.

Macromolecular design and preparation of polymersomes

From drug delivery to nanoreactors and protocells, polymersomes have gained considerable interest from researchers due to their novel applications.

Renal clearance of polymeric nanoparticles by mimicry of glycan surface of viruses

It has been shown that viral particles such as herpes simplex virus-1 and cytomegalovirus show renal clearance despite their large size (155-240 nm). Interestingly, one of the common characteristics of these viruses is their glycoprotein rich viral envelope. Since, glycosaminoglycans (GAGs) share similarities with oligosaccharide chains in the glycoproteins, we hypothesize that modification of nanoparticles (NPs) surface with naturally found GAGs could alter NP clearance characteristics by mimicking physicochemical aspects of viral glycoprotein envelope. We demonstrate that polymeric NP bearing surfaces enriched with dermatan sulfate, chondroitin sulfate, heparin sulfate, and hyaluronic acid undergo rapid renal clearance (74% of injected dose as early as 2 h) while showing reduced liver accumulation. Ultra-structural analyses suggest that the excretion of intact NPs occurs via proximal tubule secretion, but not via glomerular filtration. Finally, we demonstrate that our bioinspired NPs are able to accumulate within the epithelial tumor microenvironment despite their efficient renal clearance. Our system provides a framework to address renal toxicity associated with repeated dosing of NP and a platform to elaborate on plausible mechanism of renal clearance of virus particle.

Pharmacokinetics of nanotechnology-based formulations in pediatric populations

The development of therapeutics for pediatric use has advanced in the last few decades. However, off-label use of adult medications in pediatrics remains a significant clinical problem. Furthermore, the development of therapeutics for pediatrics is challenged by the lack of pharmacokinetic (PK) data in the pediatric population. To promote the development of therapeutics for pediatrics, the United States Pediatric Formulation Initiative recommended the investigation of nanotechnology-based delivery systems. Therefore, in this review, we provided comprehensive information on the PK of nanotechnology-based formulations from preclinical and clinical studies in pediatrics. Specifically, we discuss the relationship between formulation parameters of nanoformulations and PK of the encapsulated drug in the context of pediatrics. We review nanoformulations that include dendrimers, liposomes, polymeric long-acting injectables (LAIs), nanocrystals, inorganic nanoparticles, polymeric micelles, and protein nanoparticles. In addition, we describe the importance and need of PK modeling and simulation approaches used in predicting PK of nanoformulations for pediatric applications.

Influence of PEGylation on PLGA nanoparticle properties, hydrophobic drug release and interactions with human serum albumin

Objective

To evaluate the impact of PEG content on poly(lactic-co-glycolic acid) (PLGA) NP physicochemical properties, hydrophobic drug release (rifampicin as a model drug) and human serum protein binding.

Methods

Rifampicin loaded and unloaded nanoparticles with PEG content of 0–17% (w/w) were prepared by an emulsification–evaporation technique. Nanoparticles were characterized for size, zeta potential and morphology. PEGlyation was confirmed using proton nuclear magnetic resonance (1H NMR). Fluorescence spectroscopy and dynamic light scattering were used to determine nanoparticle-protein binding, binding constants and stability of nanoparticles in human serum, respectively. Drug loading and release were determined by UV-VIS spectroscopy and drug release data was mathematically modelled.

Key findings

A NP PEG content of 17% w/w significantly retarded release of rifampicin from PLGA NPs and altered kinetics of drug release. Stern–Volmer (Ksv) protein binding constants decreased upon PEG incorporation. A 2% w/w PEG was sufficient to significantly reduce protein binding extent to PLGA NPs and maintain particle size distributions.

Conclusion

The ability to fine tune drug release and formation of protein corona around nanoparticles is crucial to formulation scientists. This study suggests that PLGA NPs with low PEG content might be suitable for extended circulation and rapid drug release and that higher PEG content retards hydrophobic drug release.

In Vivo Evaluation of Dual-Targeted Nanoparticles Encapsulating Paclitaxel and Everolimus

A synergistic combination of paclitaxel (PTX) and everolimus (EVER) can allow for lower drug doses, reducing the toxicities associated with PTX, while maintaining therapeutic efficacy. Polymeric nanoparticles (NPs) of high stability provide opportunities to modify the toxicity profile of the drugs by ensuring their delivery to tumor at the synergistic ratio while limiting systemic drug exposure and the toxicities that result. The current study goal is to study the in vivo fate of human epidermal factor receptor 2 (HER2) and epidermal growth factor receptor (EGFR) dual-targeted PTX+EVER-loaded NPs (Dual-NPs) in an MDA-MB-231-H2N BC tumor-bearing mouse model. The pharmacokinetic parameters, plasma area under the curve (AUC) and half-life (t1/2), were found to be 20-fold and 3 to 4-fold higher, respectively, for the drugs when administered in the Dual-NPs in comparison to the free-drug combination (i.e., PTX+EVER) at an equivalent dose of PTX. While maintaining anti-tumor efficacy, the levels of body weight loss were significantly lower (p < 0.0001) and the overall degree of neurotoxicity was reduced with Dual-NP treatment in comparison to the free-drug combination when administered at an equivalent dose of PTX. This study suggests that Dual-NPs present a promising platform for the delivery of the PTX and EVER combination with the potential to reduce severe PTX-induced toxicities and in turn, improve quality of life for patients with BC.

Enhanced cutaneous wound healing in rats following topical delivery of insulin-loaded nanoparticles embedded in poly(vinyl alcohol)-borate hydrogels

Insulin plays an important role in the wound healing process, but its method of delivery to the wound bed and subsequent effect on rate of healing is less well investigated. In this study, we evaluated the therapeutic effectiveness of topical human insulin delivery using a nanoparticulate delivery system suspended in a structured hydrogel vehicle. Poly(lactide-co-glycolide) (PLGA) nanoparticles (NP) of 202.6 nm diameter and loaded with 33.86 μg insulin per milligram of polymer were formulated using a modified double-emulsion solvent evaporation technique and dispersed in a dilatant hydrogel (poly(vinyl alcohol)-borate). Importantly, this hydrogel formulation was used to achieve ultimate contact with the wound bed. A comparison of wound healing rates following local administration of insulin in the free and nanoencapsulated forms was performed in diabetic and healthy rats. In non-diabetic rats, there was no significant difference between healing observed in control and wounds treated with free insulin (p > 0.05), whereas treatment with insulin encapsulated within PLGA NP showed a significant difference (p < 0.001). In diabetic cohorts, both free insulin and nanoencapsulated insulin induced significant improvement in wound healing when compared to controls, with better percentage wound injury indices observed with the colloidal formulation. At day 10 of the experiment, the difference between percentage wound injury indices of insulin-PLGA NP and free insulin comparing to their controls were 29.15 and 12.16%, respectively. These results support strongly the potential of insulin-loaded colloidal carriers for improved wound healing when delivered using dilatant hydrogel formulations.

Improvement of N-Acetylcysteine Loaded in PLGA Nanoparticles by Nanoprecipitation Method

N-Acetylcysteine (NAC) is a hydrophilic compound with a low bioavailability. It has been used as an effective antioxidant agent. This research seeks to enhance the entrapment of NAC in PLGA nanoparticles for drug delivery systems. The nanoparticles were made using the nanoprecipitation method and changing the following parameters: the solvent/nonsolvent nature, its viscosity, pH, NAC addition to the nonsolvent, the polymer concentration and molecular weight, and NAC concentration in the solvent. The results showed that an increase in the nonsolvent viscosity produces NAC concentration in the solvent, and the nonsolvent rises its entrapment in the nanoparticles. Nanoparticles with 235.5 ± 11.4 nm size with an entrapment efficiency of 0.4 ± 0.04% and a specific load of 3.14 ± 0.33% were obtained. The results suggest that besides efficiently entrapping hydrophobic compounds, the nanoprecipitation method also has a high potential as an alternative entrapment method for hydrophilic compounds as well. However, its use in the pharmaceutical industry, as a proper specific load vehicle, still depends on the improvement of the load capacity.

Molecular engineering solutions for therapeutic peptide delivery

Proteins and their interactions in and out of cells must be well-orchestrated for the healthy functioning and regulation of the body. Even the slightest disharmony can cause diseases. Therapeutic peptides are short amino acid sequences (generally considered <50 amino acids) that can naturally mimic the binding interfaces between proteins and thus, influence protein-protein interactions. Because of their fidelity of binding, peptides are a promising next generation of personalized medicines to reinstate biological harmony. Peptides as a group are highly selective, relatively safe, and biocompatible. However, they are also vulnerable to many in vivo pharmacologic barriers limiting their clinical translation. Current advances in molecular, chemical, and nanoparticle engineering are helping to overcome these previously insurmountable obstacles and improve the future of peptides as active and highly selective therapeutics. In this review, we focus on self-assembled vehicles as nanoparticles to carry and protect therapeutic peptides through this journey, and deliver them to the desired tissue.

Development of surface-engineered PLGA nanoparticulate-delivery system of Tet1-conjugated nattokinase enzyme for inhibition of Aβ40 plaques in Alzheimer's disease

According to the World Health Organization, globally there are around 18 million patients suffering from Alzheimer’s disease (AD), and this number is expected to double by 2025. The pathophysiology of AD includes selective deposition of Aβ peptide in the mitochondria of cells, which inhibits uptake of glucose by neurons and key enzyme functions. Current drug treatments for AD are unable to rectify the underlying pathology of the disease; they only provide short-term symptomatic relief, so there is a need for the development of newer treatment regimes. The antiamyloid activity, antifibrinolytic activity, and antithrombotic activity of nattokinase holds potential for the treatment of AD. As nattokinase is a protein, its stability restricts its usage to a greater extent, but this limitation can be overcome by nanoencapsulation. In this work, we successfully synthesized polymeric nanoparticles of nattokinase and characterized its use by different techniques: transmission electron microscopy, scanning electron microscopy, DTS Nano, differential scanning calorimetry, Fourier-transform infrared spectroscopy, thioflavin T-binding assay, in vitro drug release, antifibrinolytic activity, and in vivo antiamyloid activity. As brain targeting of hydrophilic drugs is complicated due to the stringent nature of blood–brain barrier, in the current experimental study, we conjugated poly(lactic-co-glycolic acid) (PLGA)-encapsulated nattokinase with Tet1 peptide, which exhibits retrograde transportation properties because of its affinity to neurons. Our study suggests that PLGA-encapsulated nattokinase polymeric nanoparticles are able to downregulate amyloid aggregation and exhibit antifibrinolytic activity. The encapsulation of nattokinase in PLGA did not affect its enzyme activity, so the prepared nanoformulation containing nattokinase can be used as an effective drug treatment against AD.

Polyethylene Glycol-Poly-Lactide-co-Glycolide Block Copolymer-Based Nanoparticles as a Potential Tool for Off-Label Use of N-Acetylcysteine in the Treatment of Diastrophic Dysplasia

Potential off-label therapeutic role of N-acetylcysteine (N-Ac) was recently demonstrated in the treatment of diastrophic dysplasia (DTD) using mutant mice; its main drawback is the rapid clearance from blood due to the liver metabolism. Our goal was to investigate the potential of polyethylene glycol polylactide-co-glycolide block copolymer (PLGA-PEG)-based nanoparticles (NPs) in order to improve in vivo biodistribution performances and N-Ac pharmacokinetic profile after subcutaneous administration in mice. Results suggest that N-Ac can be effectively loaded into NPs (about 99 μg/mg NPs) using a suitably optimized nanoprecipitation method. Thanks to the good physical characteristics (mean diameter <100 nm, zeta potential about -8 mV) NPs can reach skeletal tissue in particular femoral head and proximal tibia epiphysis at the sixth hour after injection, remaining in the tissues till 24 h. Furthermore, pharmacokinetic study revealed a sustained N-Ac concentration in plasma with a peak concentration of 2.48 ± 1.72 μM at the 24th hour after injection. Overall, results highlight the actual interest of N-Ac-loaded PLGA-PEG NPs as useful platform for N-Ac parenteral administration.

Nano-palladium is a cellular catalyst for in vivo chemistry

Palladium catalysts have been widely adopted for organic synthesis and diverse industrial applications given their efficacy and safety, yet their biological in vivo use has been limited to date. Here we show that nanoencapsulated palladium is an effective means to target and treat disease through in vivo catalysis. Palladium nanoparticles (Pd-NPs) were created by screening different Pd compounds and then encapsulating bis[tri(2-furyl)phosphine]palladium(II) dichloride in a biocompatible poly(lactic-co-glycolic acid)-b-polyethyleneglycol platform. Using mouse models of cancer, the NPs efficiently accumulated in tumours, where the Pd-NP activated different model prodrugs. Longitudinal studies confirmed that prodrug activation by Pd-NP inhibits tumour growth, extends survival in tumour-bearing mice and mitigates toxicity compared to standard doxorubicin formulations. Thus, here we demonstrate safe and efficacious in vivo catalytic activity of a Pd compound in mammals.

Palladium (Pd) is a well-known catalyst in organic chemistry but its use in nanomedicine is limited. Here, the authors design a Pd nanoparticle that triggers the activation of an antitumour prodrug in vivo, which shows efficacy and improves toxicity compared to traditional solvent- and nanoparticle-drug formulations.

Efficacy assessment of self-assembled PLGA-PEG-PLGA nanoparticles: Correlation of nano-bio interface interactions, biodistribution, internalization and gene expression studies

The aim of our study was to develop and compare the biological performance of two types of biodegradable SN-38 loaded nanoparticles (NPs) with various surface properties, composed of low and high Mw triblock PLGA-PEG-PLGA copolymers, applying rational quality and safety by design approach. Therefore, along with the optimization of crucial physico-chemical properties and in order to evaluate the therapeutical potential and biocompatibility of prepared polymeric nanoparticles, analysis of nano-bio interactions, cell internalization, gene expression and biodistribution studies were performed. The optimized formulations, one of low Mw and one composed of high Mw PLGA-PEG-PLGA copolymer, exhibited different characteristics in terms of surface properties, particle size, zeta potential, drug loading, protein adsorption and biodistribution, which may be attributed to the variations in nano-bio interface interactions due to different NP building blocks length and Mw. On the contrary to protein adsorption and biodistribution studies, both types of NPs exhibited similar results during cell internalization and gene expression studies performed in cell culture medium containing serum proteins. This pool of useful data for internalization and efficacy as well as the notable advance in the circulation time of low Mw NPs may be further employed for shaping the potential of the designed nanocarriers.

Vincristine and ɛ-viniferine-loaded PLGA-b-PEG nanoparticles: pharmaceutical characteristics, cellular uptake and cytotoxicity

The objective of this study was to prepare the ɛ-viniferine and vincristine-loaded PLGA-b-PEG nanoparticle and to investigate advantages of these formulations on the cytotoxicity of HepG2 cells. Prepared nanoparticle has shown a homogeneous distribution with 113 ± 0.43 nm particle size and 0.323 ± 0.01 polydispersity index. Zeta potential was determined as -35.03 ± 1.0 mV. The drug-loading percentages were 6.01 ± 0.23 and 2.01 ± 0.07 for ɛ-viniferine and vincristine, respectively. The cellular uptake efficiency of coumarin-6-loaded nanoparticles was increased up to 87.8% after 4 h. Nanoparticles loaded with high concentrations of both drugs showed a cytotoxic effect on HepG2 cells, having the percentage of cell viability of between 43.23% and 47.37%. Unfortunately, the percentage of apoptotic cells after treated with drugs-loaded nanaoparticles (10.93%) was similar to free forms of drugs (12.1%) that might be due to low ɛ-viniferine release in biological pH at 24 h.

Luteinizing hormone-releasing hormone peptide tethered nanoparticulate system for enhanced antitumoral efficacy of paclitaxel

Aim: Paclitaxel (PTX) is an effective anticancer agent used in the therapy of a wide variety of cancers. However, the drug is difficult to formulate due to its low solubility, and therefore, it is administered under slow infusion with castor oil/ethanol solution as surfactant that causes serious side effects. This investigation investigates leutinizing hormone releasing hormone (LHRH)-tethered nanparticulate system as modality for cancer-specific delivery of PTX and therefore minimizing the adverse effects. Materials & methods: LHRH-tethered poly(lactic-co-glycolic acid) copolymer with poly ethylene glycol side chain was synthesized, characterized and employed to formulate PTX-loaded nanoparticulate system. Results & conclusion: The developed nanoparticulate appears to be proficient in carrying as well as targeted delivery of PTX with improved therapeutic efficacy and better safety.

Bioavailability of Orally Delivered Alpha-Tocopherol by Poly(Lactic-Co-Glycolic) Acid (PLGA) Nanoparticles and Chitosan Covered PLGA Nanoparticles in F344 Rats

It is hypothesized that the bioavailability of αT (alpha-tocopherol), an antioxidant, can be improved when delivered by poly(lactic-co-glycolic) acid (PLGA) nanoparticles (NPs) and chitosan covered PLGA nanoparticles (PLGA-Chi NPs), and that the mucoadhesive properties of chitosan may enhance absorption of αT. PLGA and PLGA-Chi NPs were characterized by measuring entrapment efficiency, size, polydispersity, and zeta potential. Nanoparticle physical stability, chemical stability of entrapped αT, and release kinetics were also measured. Pharmacokinetic studies were conducted by administering PLGA (αT) NPs, PLGA-Chi (αT) NPs, and free αT via oral gavage in rats. The size and zeta potential of the two particle systems were 97.87 ± 2.63 nm and -36.2 ± 1.31 mV for PLGA(αT) NPs, and 134 ± 2.05 nm and 38.0 ± 2.90 mV for PLGA-Chi (αT) nanoparticles in DI water. The particle systems showed to be stable during various in vitro assays. Bioavailability of nanodelivered αT was improved compared to the free αT, by 170% and 121% for PLGA and PLGA-Chi NPs, respectively. It was concluded that while chitosan did not further improved bioavailability of αT, PLGA NPs protected the entrapped drug from the GI environment degradation and proved to be an effective delivery system for αT.

Preparation and in vivo evaluation of insulin-loaded biodegradable nanoparticles prepared from diblock copolymers of PLGA and PEG

The aim of this study was to design a controlled release vehicle for insulin to preserve its stability and biological activity during fabrication and release. A modified, double emulsion, solvent evaporation, technique using homogenisation force optimised entrapment efficiency of insulin into biodegradable nanoparticles (NP) prepared from poly (DL-lactic-co-glycolic acid) (PLGA) and its PEGylated diblock copolymers. Formulation parameters (type of polymer and its concentration, stabiliser concentration and volume of internal aqueous phase) and physicochemical characteristics (size, zeta potential, encapsulation efficiency, in vitro release profiles and in vitro stability) were investigated. In vivo insulin sensitivity was tested by diet-induced type II diabetic mice. Bioactivity of insulin was studied using Swiss TO mice with streptozotocin-induced type I diabetic profile. Insulin-loaded NP were spherical and negatively charged with an average diameter of 200-400 nm. Insulin encapsulation efficiency increased significantly with increasing ratio of co-polymeric PEG. The internal aqueous phase volume had a significant impact on encapsulation efficiency, initial burst release and NP size. Optimised insulin NP formulated from 10% PEG-PLGA retained insulin integrity in vitro, insulin sensitivity in vivo and induced a sustained hypoglycaemic effect from 3h to 6 days in type I diabetic mice.

Spatiotemporal release of BMP-2 and VEGF enhances osteogenic and vasculogenic differentiation of human mesenchymal stem cells and endothelial colony-forming cells co-encapsulated in a patterned hydrogel

Reconstruction of large bone defects is limited by insufficient vascularization and slow bone regeneration. The objective of this work was to investigate the effect of spatial and temporal release of recombinant human bone morphogenetic protein-2 (BMP2) and vascular endothelial growth factor (VEGF) on the extent of osteogenic and vasculogenic differentiation of human mesenchymal stem cells (hMSCs) and endothelial colony-forming cells (ECFCs) encapsulated in a patterned hydrogel. Nanogels (NGs) based on polyethylene glycol (PEG) macromers chain-extended with short lactide (L) and glycolide (G) segments were used for grafting and timed-release of BMP2 and VEGF. NGs with 12kDa PEG molecular weight (MW), 24 LG segment length, and 60/40L/G ratio (P12-II, NG(10)) released the grafted VEGF in 10days. NGs with 8kDa PEG MW, 26 LG segment length, and 60/40L/G ratio (P8-I, NG(21)) released the grafted BMP2 in 21days. hMSCs and NG-BMP2 were encapsulated in a patterned matrix based on acrylate-functionalized lactide-chain-extended star polyethylene glycol (SPELA) hydrogel and microchannel patterns filled with a suspension of hMSCs+ECFCs and NG-VEGF in a crosslinked gelatin methacryloyl (GelMA) hydrogel. Groups included patterned constructs without BMP2/VEGF (None), with directly added BMP2/VEGF, and NG-BMP2/NG-VEGF. Based on the results, timed-release of VEGF in the microchannels in 10days from NG(10) and BMP2 in the matrix in 21days from NG(21) resulted in highest extent of osteogenic and vasculogenic differentiation of the encapsulated hMSCs and ECFCs compared to direct addition of VEGF and BMP2. Further, timed-release of VEGF from NG(10) in hMSC+ECFC encapsulating microchannels and BMP2 from NG(21) in hMSC encapsulating matrix sharply increased bFGF expression in the patterned constructs. The results suggest that mineralization and vascularization are coupled by localized secretion of paracrine signaling factors by the differentiating hMSCs and ECFCs.

Tumour-associated macrophages act as a slow-release reservoir of nano-therapeutic Pt(IV) pro-drug

Therapeutic nanoparticles (TNPs) aim to deliver drugs more safely and effectively to cancers, yet clinical results have been unpredictable owing to limited in vivo understanding. Here we use single-cell imaging of intratumoral TNP pharmacokinetics and pharmacodynamics to better comprehend their heterogeneous behaviour. Model TNPs comprising a fluorescent platinum(IV) pro-drug and a clinically tested polymer platform (PLGA-b-PEG) promote long drug circulation and alter accumulation by directing cellular uptake toward tumour-associated macrophages (TAMs). Simultaneous imaging of TNP vehicle, its drug payload and single-cell DNA damage response reveals that TAMs serve as a local drug depot that accumulates significant vehicle from which DNA-damaging Pt payload gradually releases to neighbouring tumour cells. Correspondingly, TAM depletion reduces intratumoral TNP accumulation and efficacy. Thus, nanotherapeutics co-opt TAMs for drug delivery, which has implications for TNP design and for selecting patients into trials.

Impact of Surface Polyethylene Glycol (PEG) Density on Biodegradable Nanoparticle Transport in Mucus ex Vivo and Distribution in Vivo

Achieving sustained drug delivery to mucosal surfaces is a major challenge due to the presence of the protective mucus layer that serves to trap and rapidly remove foreign particulates. Nanoparticles engineered to rapidly penetrate mucosal barriers (mucus-penetrating particles, "MPP") have shown promise for improving drug distribution, retention and efficacy at mucosal surfaces. MPP are densely coated with polyethylene glycol (PEG), which shields the nanoparticle core from adhesive interactions with mucus. However, the PEG density required to impart the "stealth" properties to nanoparticles in mucus, and thus, uniform distribution in vivo, is still unknown. We prepared biodegradable poly(lactic-co-glycolic acid) (PLGA) nanoparticles with a range of PEG surface densities by blending various ratios of a diblock copolymer of PLGA and 5 kDa poly(ethylene glycol) (PLGA-PEG5k) with PLGA. We then evaluated the impact of PEG surface density, measured using an (1)H NMR method, on mucin binding in vitro, nanoparticle transport in freshly obtained human cervicovaginal mucus (CVM) ex vivo, and nanoparticle distribution in the mouse cervicovaginal tract in vivo. We found that at least 5% PEG was required to effectively shield the nanoparticle core from interacting with mucus components in vitro and ex vivo, thus leading to enhanced nanoparticle distribution throughout the mouse vagina in vivo. We then demonstrated that biodegradable MPP could be formulated from blends of PLGA and PLGA-PEG polymers of various molecular weights, and that these MPP provide tunable drug loading and drug release rates and durations. Overall, we describe a methodology for rationally designing biodegradable, drug-loaded MPP for more uniform delivery to the vagina.

Nanocarriers for photodynamic therapy-rational formulation design and medium-scale manufacture

The development and manufacture of novel nanocarriers for drug delivery has proved challenging with regards to scale-up and pharmaceutical quality. Polymeric nanocarriers composed of poly(lactic-co-glycolic acid)-b-poly(ethylene glycol) (PLGA-PEG) were prepared and the photosensitizer meso-tetrakis(3-hydroxyphenyl) chlorin (mTHPC) was effectively encapsulated. Furthermore, the interplay of various process and formulation parameters and their impact on the most important product specifications were investigated by using a factorial design and a central composite design in a microfluidic manufacturing process. These nanoparticles for intravenous administration with a size of 97 ± 0.13 nm, narrow size distribution, and an encapsulation efficiency of more than 80% were produced at high throughput. In vitro stability and in vitro drug release testing were applied for quality control purposes. Finally, the toxicity of the photosensitizer was tested in vitro. The cytotoxicity was successfully reduced while the efficacy of the formulation was maintained. First observations using in vivo imaging suggest effective distribution of the nanocarrier system after injection into rodents. Thus, further in vivo testing of the beneficial effects of nanoencapsulation into the matrix system and its formulation will be considered for the delivery of mTHPC to tumor tissues during photodynamic therapy.

Nanobody conjugated PLGA nanoparticles for active targeting of African Trypanosomiasis

Targeted delivery of therapeutics is an alternative approach for the selective treatment of infectious diseases. The surface of African trypanosomes, the causative agents of African trypanosomiasis, is covered by a surface coat consisting of a single variant surface glycoprotein, termed VSG. This coat is recycled by endocytosis at a very high speed, making the trypanosome surface an excellent target for the delivery of trypanocidal drugs. Here, we report the design of a drug nanocarrier based on poly ethylen glycol (PEG) covalently attached (PEGylated) to poly(D,L-lactide-co-glycolide acid) (PLGA) to generate PEGylated PLGA nanoparticles. This nanocarrier was coupled to a single domain heavy chain antibody fragment (nanobody) that specifically recognizes the surface of the protozoan pathogen Trypanosoma brucei. Nanoparticles were loaded with pentamidine, the first-line drug for T. b. gambiense acute infection. An in vitro effectiveness assay showed a 7-fold decrease in the half-inhibitory concentration (IC50) of the formulation relative to free drug. Furthermore, in vivo therapy using a murine model of African trypanosomiasis demonstrated that the formulation cured all infected mice at a 10-fold lower dose than the minimal full curative dose of free pentamidine and 60% of mice at a 100-fold lower dose. This nanocarrier has been designed with components approved for use in humans and loaded with a drug that is currently in use to treat the disease. Moreover, this flexible nanobody-based system can be adapted to load any compound, opening a range of new potential therapies with application to other diseases.

Exploiting the tumor phenotype using biodegradable submicron carriers of chemotherapeutic drugs

Tumor tissues possess characteristics that distinguish them from healthy tissues and make them attractive targets for submicron carriers of chemotherapeutic drugs (CTX). CTX are generally administered systemically in free form to cancer patients resulting in unwanted cytotoxic effects and placing limitations on the deliverable CTX dose. In an effort to raise the therapeutic index of CTX there are now liposome-based CTX formulations in clinical use that are more tumor specific than the free form of CTX. However, progression to liposome-based chemotherapy in the clinic has been slow and there have been no approved formulations introduced in the last decade. Alternative carrier systems such as those made from the biodegradable polymer poly(lactic-co-glycolic) acid (PLGA) have been investigated in preclinical settings with promising outcomes. Here we review the principle behind biodegradable submicron carriers as CTX delivery vehicles for solid tumors with a specific focUS on liposomes and PLGA-based carriers, highlighting the strengths and weaknesses of each system.

Novel PEG-grafted nanostructured lipid carrier for systematic delivery of a poorly soluble anti-leukemia agent Tamibarotene: characterization and evaluation

Tamibarotene (Am80), a poorly water-soluble drug for the treatment of acute promyelocytic leukemia (APL), loaded nanostructured lipid carrier (Am80-NLC) was developed and characterized previously. The purpose of the present work was to develop PEGylated nanostructured lipid carrier (PEG-NLC) for intravenous delivery of Am80, with the aim to further extend the circulation in blood and decrease the adverse events. Am80-loaded PEG-NLC (Am80-PEG-NLC) modified with PEG-40 stearate (PEG40-SA, molecular weight 2000 Da) was formulated by the method of melt-emulsification and low temperature-solidification technique. Am80-NLC was developed as well as control. Based on the optimized results of single-factor screening experiment, the average drug entrapment efficiency, the mean particle size, and zeta potential of Am80-NLC and Am80-PEG-NLC were found to be 89.8-94.3%, 178.9-201.6 nm, and -37.74 to -20.1 mV, respectively. In vitro drug release of Am80-NLC and Am80-PEG-NLC possessed a sustained release characteristic and their release behavior was in accordance with the Ritger-Peppas equation. In vivo, after intravenous (i.v.) injection to rats, the mean residence time (MRT) of Am80-PEG-NLC group was significantly prolonged and the AUC value was improved as well compared with the Am80-NLC group. Furthermore, the biodistribution in mice showed that Am80-PEG-NLC preferentially decreased the accumulation of Am80 in kidney and increased the drug concentration in brain after i.v. injection. In conclusion, Am80-PEG-NLC may be a potential delivery system for Am80 in the treatment of APL.

Polymeric nanotherapeutics: clinical development and advances in stealth functionalization strategies

Long-circulating polymeric nanotherapeutics have garnered increasing interest in research and in the clinic owing to their ability to improve the solubility and pharmacokinetics of therapeutic cargoes. Modulation of carrier properties promises more effective drug localization at the disease sites and can lead to enhanced drug safety and efficacy. In the present review, we highlight the current development of polymeric nanotherapeutics in the clinic. In light of the importance of stealth properties in therapeutic nanoparticles, we also review the advances in stealth functionalization strategies and examine the performance of different stealth polymers in the literature. In addition, we discuss the recent development of biologically inspired "self" nanoparticles, which present a differing stealth concept from conventional approaches.

The effect of nanoparticle properties, detection method, delivery route and animal model on poly(lactic-co-glycolic) acid nanoparticles biodistribution in mice and rats

A review of poly(lactic-co-glycolic) acid (PLGA) nanoparticle (NP) biodistribution was conducted with the intent of identifying particle behavior for drug delivery applications. Databases such as Science Direct and Web of Science were used to locate papers on biodistribution of intravenous (i.v.) and orally delivered PLGA NPs in mice and rats. The papers included in the review were limited to those that report biodistribution data in terms of % dose particles/g tissue in the liver, kidney, spleen, lung, heart and brain. Noted trends involved particle behavior based on individual organ, particle size, animal model, type of indicator (entrapped versus covalently linked) and method of delivery (oral or i.v.). The liver showed the highest uptake of particles in mice, and the lung showed the highest uptake in rats. Minimal amounts of particles were detected in both the heart and brain of rats and mice. In rats, the concentration of particles approached 0% dose/g or decreased significantly over 24 h after administration of a single dose of particles. Higher concentrations of smaller particles were evident in the liver, kidney and spleen. Orally delivered drugs showed little to no uptake within the 24 h analysis when compared with i.v. delivered NPs. Differences in particle concentrations between rats and mice were also observed as expected when expressed as % dose/g organ. Particles with covalently linked indicators showed lower concentrations in tissues than particles with physically entrapped indicators. Further research on oral delivery of PLGA NPs as well as distribution beyond 24 h is needed to fully understand particle behavior in vivo for successful application of NPs in drug delivery.

The impact of PEGylation patterns on the in vivo biodistribution of mixed shell micelles

Polyethylene glycol (PEG)-ylation is a widely used strategy to fabricate nanocarriers with a long blood circulation time. Further elaboration of the contribution of the surface PEGylation pattern to biodistribution is highly desirable. We fabricated a series of polyion complex (PIC) micelles PEGylated with different ratios (PEG2k and PEG550). The plasma protein adsorption, murine macrophage uptake, and in vivo biodistribution with iodine-125 as the tracer were systematically studied to elucidate the impact of PEGylation patterns on the biodistribution of micelles. We demonstrated that the PEGylated micelles with short hydrophilic PEG chains mixed on the surface were cleared quickly by the reticuloendothelial system (RES), and the single PEG2k PEGylated micelles could efficiently prolong the blood circulation time and increase their deposition in tumor sites. The present study extends the understanding of the PEGylation strategy to further advance the development of ideal nanocarriers for drug delivery and imaging applications.