Dexamethasone/PLGA microspheres for continuous delivery of an anti-inflammatory drug for implantable medical devices

Preparation and evaluation of fenbendazole methyl-β-cyclodextrin inclusion complexes

As an orally effective benzimidazole anthelmintic agent, fenbendazole was not only widely used in agriculture and animal husbandry to prevent and treat parasites, but also shows anti-cancer effects against several types of cancer, exhibits anti-cancer effects in paclitaxel and doxorubicin-resistant cancer cells. However, fenbendazole's poor in water solubility (0.3 µg/mL), limits its clinical applications. Even great efforts were made toward increasing its water solubility, the results were not significant to reach anti-cancer drug delivery requirement (5-10 mg/mL). Through single factor and orthogonal strategy, many complex conditions were designed and used to prepare the complexes, the inclusion complex with methyl-β-cyclodextrin with 29.2 % of inclusion rate and 89.5% of inclusion yield can increase drug's water solubility to 20.21 mg/mL, which is the best result so far. Its structure was confirmed by differential scanning calorimetry, scanning electron microscopic image, 1D and 2D NMR spectra in D2O. In its in vitro pharmacokinetic study, fenbendazole was 75% released in 15 min., in its in vivo pharmacokinetic study, the bio-availabilities of fenbendazole, its major metabolic anthelmintic agent oxfendazole and its minor metabolic anthelmintic agent oxfendazole were increased to 138%, 149% and 169% respectively, which would allow for fewer drug doses to achieve the same therapeutic effect and suggest that the complex can be used as a potential anticancer agent.

Controlled Release of Drugs from Extracellular Matrix-Derived Peptide-Based Nanovesicles through Tailored Noncovalent Interactions

Elastin-collagen nanovesicles (ECnV) have emerged as a promising platform for drug delivery due to their tunable physicochemical properties and biocompatibility. The potential of nine distinct ECnVs to serve as drug-delivery vehicles was investigated in this study, and it was demonstrated that various small-molecule cargo (e.g., dexamethasone, methotrexate, doxorubicin) can be encapsulated in and released from a set of ECnVs, with extents of loading and rates of release dictated by the composition of the elastin domain of the ECnV and the type of cargo. Elastin-like peptides (ELPs) and collagen-like peptides (CLPs) of various compositions were produced; the secondary structure of the corresponding peptides was determined using CD, and the morphology and average hydrodynamic diameter (∼100 nm) of the ECnVs were determined using TEM and DLS. It was observed that hydrophobic drugs exhibited slower release kinetics than hydrophilic drugs, but higher drug loading was achieved for the more hydrophilic Dox. The collagen-binding ability of the ECnVs was demonstrated through a 2D collagen-binding assay, suggesting the potential for longer retention times in collagen-enriched tissues or matrices. Sustained release of drugs for up to 7 days was observed and, taken together with the collagen-binding data, demonstrates the potential of this set of ECnVs as a versatile drug delivery vehicle for longer-term drug release of a variety of cargo. This study provides important insights into the drug delivery potential of ECnVs and offers useful information for future development of ECnV-based drug delivery systems for the treatment of various diseases.

Preparation of PLGA Microspheres Using the Non-Toxic Glycofurol as Polymer Solvent by a Modified Phase Inversion Methodology

Poly(D,L-lactide-co-glycolide is a biodegradable copolymer that can release pharmaceuticals. These pharmaceuticals can provide local therapy and also avert the clinical issues that occur when a drug must be given continuously and/or automatically. However, the drawbacks of using poly(D,L-lactide-co-glycolide include the kinetics and duration of time of poly(D,L-lactide-co-glycolide drug release, the denaturing of the drug loaded drug, and the potential clinical side effects. These drawbacks are mainly caused by the volatile organic solvents needed to prepare poly(D,L-lactide-co-glycolide spheres. Using the non-toxic solvent glycofurol solvent instead of volatile organic solvents to construct poly(D,L-lactide-co-glycolide microspheres may deter the issues of using volatile organic solvents. Up to now, preparation of such glycofurol spheres has previously met with limited success. We constructed dexamethasone laden poly(D,L-lactide-co-glycolide microspheres utilizing glycofurol as the solvent within a modified phase inversion methodology. These prepared microspheres have a higher drug load and a lower rate of water diffusion. This prolongs drug release compared to dichloromethane constructed spheres. The glycofurol-generated spheres are also not toxic to target cells as is the case for dichloromethane-constructed spheres. Further, glycofurol-constructed spheres do not denature the dexamethasone molecule and have kinetics of drug release that are more clinically advantageous, including a lower drug burst and a prolonged drug release.

Neutrophil-targeted combinatorial nanosystems for suppressing bacteremia-associated hyperinflammation and MRSA infection to improve survival rates

There is currently no specific and effective treatment for bacteremia-mediated sepsis. Hence, this study engineered a combinatorial nanosystem containing neutrophil-targeted roflumilast-loaded nanocarriers and non-targeted fusidic acid-loaded nanoparticles to enable the dual mitigation of bacteremia-associated inflammation and methicillin-resistant Staphylococcus aureus (MRSA) infection. The targeted nanoparticles were developed by conjugating anti-lymphocyte antigen 6 complex locus G6D (Ly6G) antibody fragment on the nanoparticulate surface. The particle size and zeta potential of the as-prepared nanosystem were about 200 nm and -25 mV, respectively. The antibody-conjugated nanoparticles showed a three-fold increase in neutrophil internalization compared to the unfunctionalized nanoparticles. As a selective phosphodiesterase (PDE) 4 inhibitor, the roflumilast in the nanocarriers largely inhibited cytokine/chemokine release from the activated neutrophils. The fusidic acid-loaded nanocarriers were vital to eliminate biofilm MRSA colony by 3 log units. The nanoparticles drastically decreased the intracellular bacterial count compared to the free antibiotic. The in vivo mouse bioimaging demonstrated prolonged retention of the nanosystem in the circulation with limited organ distribution and liver metabolism. In the mouse bacteremia model, the multifunctional nanosystem produced a 1‒2 log reduction of MRSA burden in peripheral organs and blood. The functionalized nanosystem arrested the cytokine/chemokine overexpression greater than the unfunctionalized nanocarriers and free drugs. The combinatory nanosystem also extended the median survival time from 50 to 103 h. No toxicity from the nanoformulation was found based on histology and serum biochemistry. Furthermore, our data proved that the active neutrophil targeting by the versatile nanosystem efficiently alleviated MRSA infection and organ dysfunction caused by bacteremia. STATEMENT OF SIGNIFICANCE: Bacteremia-mediated sepsis poses a significant challenge in clinical practice, as there is currently no specific and effective treatment available. In our study, we have developed a novel combinatorial nanosystem to address this issue. Our nanosystem consists of neutrophil-targeted roflumilast-loaded nanocarriers and non-targeted fusidic acid-loaded nanoparticles, enabling the simultaneous mitigation of bacteremia-associated inflammation and MRSA infection. Our nanosystem demonstrated the decreased neutrophil activation, effective inhibition of cytokine release, elimination of MRSA biofilm colonies, and reduced intracellular bacterial counts. In vivo experiments showed prolonged circulation, limited organ distribution, and increased survival rates in a mouse bacteremia model. Importantly, our nanosystem exhibited no toxicity based on comprehensive assessments.

Development and optimization of sustained release triptolide microspheres

Rheumatoid arthritis is considered a chronic systemic autoimmune disorder that may cause joint destruction. Triptolide, an active component isolated from Tripterygium wilfordii Hook.f., is considered to have promising potential for clinical use in treating rheumatoid arthritis. However, its clinical application has been limited by the narrow therapeutic window, side effects associated with plasma drug fluctuations, low oral bioavailability, and poor patient compliance with the long and frequent dosing regimen. An extended drug release preparation may address these limitations. The aim of this work was therefore to develop, formulate and optimize sustained release triptolide microspheres with poly (lactide-co-glycolide) (PLGA). Triptolide-loaded microspheres were prepared using PLGA as the matrix polymer, dichloromethane as the oil phase, and polyvinyl alcohol (PVA) as the matrix forming emulsifier. An oil-in-water (O/W) emulsion solvent evaporation technique was utilized to prepare the microspheres. Surface response methodology (RSM) coupled with central composite design (CCD) was used to optimize the formulation and a total of twenty formulations were prepared. PVA concentration (X1), PLGA concentration (X2), and theoretical drug content (X3) were selected as independent variables; and drug content (Y1), encapsulation efficiency (Y2), mean diameter (Y3) and the initial release during the first day (Y4) were taken as the response variables. The optimized formulation showed mean diameter of 42.36 μm, drug content of 7.96%, encapsulation efficiency of 80.16% and an initial release of 14.48%. The prepared microspheres exhibited a sustained release profile of triptolide in vitro over 4 weeks, which was wellfitted with a Korsmeyer-Peppas equation. However, the initial drug release (~14%) of triptolide-loaded microspheres was very high and should be specifically investigated in future studies. The results indicate that long-term sustained release microspheres of triptolide can be considered a strategy to overcome the low bioavailability and poor patient compliance with conventional triptolide tablets. The issue of initial burst release and in vivo evaluations should be specifically investigated in the future.

Topical Sustained-Release Dexamethasone-Loaded Chitosan Nanoparticles: Assessment of Drug Delivery Efficiency in a Rabbit Model of Endotoxin-Induced Uveitis

Uveitis is an ocular illness that if not treated properly can lead to a total loss of vision. In this study, we evaluated the utility of HA-coated Dexamethasone-sodium-phosphate (DEX)-chitosan nanoparticles (CSNPs) coated with hyaluronic acid (HA) as a sustained ocular delivery vehicle for the treatment of endotoxin-induced-uveitis (EIU) in rabbits. The CSNPs were characterized for particle size, zeta potential, polydispersity, surface morphology, and physicochemical properties. Drug encapsulation, in vitro drug release, and transcorneal permeation were also evaluated. Finally, eye irritation, ocular pharmacokinetics, and pharmacodynamics were in vivo. The CSNPs ranged from 310.4 nm and 379.3 nm pre-(uncoated) and post-lyophilization (with HA-coated), respectively. The zeta potentials were +32 mV (uncoated) and -5 mV (HA-uncoated), while polydispersity was 0.178-0.427. Drug encapsulation and loading in the CSNPs were 73.56% and 6.94% (uncoated) and 71.07% and 5.54% (HA-coated), respectively. The in vitro DEX release over 12 h was 77.1% from the HA-coated and 74.2% from the uncoated NPs. The physicochemical properties of the CSNPs were stable over a 3-month period when stored at 25 °C. Around a 10-fold increased transcorneal-flux and permeability of DEX was found with HA-CSNPs compared to the DEX-aqueous solution (DEX-AqS), and the eye-irritation experiment indicated its ocular safety. After the ocular application of the CSNPs, DEX was detected in the aqueous humor (AH) till 24 h. The area under the concentrations curve (AUC0-24h) for DEX from the CSNPs was 1.87-fold (uncoated) and 2.36-fold (HA-coated) higher than DEX-AqS. The half-life (t1/2) of DEX from the uncoated and HA-coated NPs was 2.49-and 3.36-fold higher, and the ocular MRT0-inf was 2.47- and 3.15-fold greater, than that of DEX-AqS, respectively. The EIU rabbit model showed increased levels of MPO, TNF-α, and IL-6 in AH. Topical DEX-loaded CSNPs reduced MPO, TNF-α, and IL-6 levels as well as inhibited NF-κB expression. Our findings demonstrate that the DEX-CSNPs platform has improved the delivery properties and, hence, the promising anti-inflammatory effects on EIU in rabbits.

Anti-cancer effect of fenbendazole-incorporated PLGA nanoparticles in ovarian cancer

OBJECTIVE

Fenbendazole (FZ) has potential anti-cancer effects, but its poor water solubility limits its use for cancer therapy. In this study, we investigated the anti-cancer effect of FZ with different drug delivery methods on epithelial ovarian cancer (EOC) in both in vitro and in vivo models.

METHODS

EOC cell lines were treated with FZ and cell proliferation was assessed. The effect of FZ on tumor growth in cell line xenograft mouse model of EOC was examined according to the delivery route, including oral and intraperitoneal administration. To improve the systemic delivery of FZ by converting fat-soluble drugs to hydrophilic, we prepared FZ-encapsulated poly(D,L-lactide-co-glycolide) acid (PLGA) nanoparticles (FZ-PLGA-NPs). We investigated the preclinical efficacy of FZ-PLGA-NPs by analyzing cell proliferation, apoptosis, and in vivo models including cell lines and patient-derived xenograft (PDX) of EOC.

RESULTS

FZ significantly decreased cell proliferation of both chemosensitive and chemoresistant EOC cells. However, in cell line xenograft mouse models, there was no effect of oral FZ treatment on tumor reduction. When administered intraperitoneally, FZ was not absorbed but aggregated in the intraperitoneal space. We synthesized FZ-PLGA-NPs to obtain water solubility and enhance drug absorption. FZ-PLGA-NPs significantly decreased cell proliferation in EOC cell lines. Intravenous injection of FZ-PLGA-NP in xenograft mouse models with HeyA8 and HeyA8-MDR significantly reduced tumor weight compared to the control group. FZ-PLGA-NPs showed anti-cancer effects in PDX model as well.

CONCLUSION

FZ-incorporated PLGA nanoparticles exerted significant anti-cancer effects in EOC cells and xenograft models including PDX. These results warrant further investigation in clinical trials.

Transscleral Delivery of Dexamethasone-Loaded Microparticles Using a Dissolving Microneedle Array

Microneedles (MNs) have attracted considerable interest as a means of ocular drug delivery, a challenging delivery route due to the limitations imposed by the various biological barriers associated with this organ. In this study, a novel ocular drug delivery system was developed by formulating a dissolvable MN array containing dexamethasone-loaded PLGA microparticles for scleral drug deposition. The microparticles serve as a drug reservoir for controlled transscleral delivery. The MNs displayed sufficient mechanical strength to penetrate the porcine sclera. Dexamethasone (Dex) scleral permeation was significantly higher than in topically instilled dosage forms. The MN system was able to distribute the drug through the ocular globe, with 19.2% of the administered Dex detected in the vitreous humour. Additionally, images of the sectioned sclera confirmed the diffusion of fluorescent-labelled microparticles within the scleral matrix. The system therefore represents a potential approach for minimally invasive Dex delivery to the posterior of the eye, which lends itself to self-administration and hence high patient convenience.

Long-acting PLGA microspheres: advances in excipient and product analysis toward improved product understanding

Poly(lactic-co-glycolic acid) (PLGA) microspheres are a sustained-release drug delivery system with several successful commercial products used for the treatment of a variety of diseases. By utilizing PLGA polymers with different compositions, therapeutic agents can be released over durations varying from several weeks to several months. However, precise quality control of PLGA polymers and a fundamental understanding of all the factors associated with the performance of PLGA microsphere formulations remains challenging. This knowledge gap can hinder product development of both innovator and generic products. In this review, variability of the key release controlling excipient (PLGA), as well as advanced physicochemical characterization techniques for the PLGA polymer and PLGA microspheres are discussed. The relative merits and challenges of different in vitro release testing methods, in vivo pharmacokinetic studies, and in vitro-in vivo correlation development are also summarized. This review is intended to provide an in-depth understanding of long-acting microsphere products and consequently facilitate the development of these complex products.

Drug release mechanisms of high-drug-load, melt-extruded dexamethasone intravitreal implants

Ozurdex is an FDA-approved sustained-release, biodegradable implant formulated to deliver the corticosteroid dexamethasone to the posterior segment of the eye for up to 6 months. Hot-melt extrusion is used to prepare the 0.46 mm × 6 mm, rod-shaped implant by embedding the drug in a matrix of poly(lactic-co-glycolic acid) (PLGA) in a 60:40 drug:polymer ratio by weight. In our previous work, the Ozurdex implant was carefully studied and reverse engineered to produce a compositionally and structurally equivalent implant for further analysis. In this work, the reverse-engineered implant is thoroughly characterized throughout the in vitro dissolution process to elucidate the mechanisms of controlled drug release. The implant exhibits a triphasic release profile in 37 °C normal saline with a small burst release (1-2 %), a one-week lag phase with limited release (less than10 %), and a final phase where the remainder of the dose is released over 3-4 weeks. The limited intermolecular interaction between dexamethasone and PLGA renders the breakdown of the polymer the dominating mechanism of controlled release. A close relationship between drug release and total implant mass loss was observed. Unique chemical and structural differences were seen between the core of the implant and the implant surface driven by diffusional limitations, autocatalytic hydrolysis, and osmotic effects.

Reverse engineering the Ozurdex dexamethasone intravitreal implant

Ozurdex is a biodegradable implant formulated for sustained-release delivery of the corticosteroid dexamethasone to the posterior segment of the eye. The small, rod-shaped implant is administered directly to the vitreous using a dedicated applicator, and releases drug for up to 6 months after administration. Sustained release is achieved by embedding dexamethasone in a matrix of 50:50 poly(lactic-co-glycolic acid) (PLGA). In this work, the Ozurdex implant was thoroughly characterized to enable the reverse engineering of a compositionally and structurally equivalent implant. Advanced imaging techniques such as scanning electron microscopy (SEM) and microcomputed tomography (microCT) revealed that the Ozurdex implant exhibits an irregular surface and an internal porosity of 6% due to a large number of discrete voids approximately 3 μm in diameter. Thermal and spectroscopic analyses showed limited interaction between the drug and the polymer, resulting in a two-phase system of dexamethasone crystals embedded within a PLGA matrix. Reverse-engineered implants with properties similar to Ozurdex were prepared using a two-step hot-melt extrusion process. The reverse-engineered implants exhibited a triphasic drug release profile similar to Ozurdex. This work seeks to provide insight into the manufacturing process and characterization of PLGA-based solid implants to support future generic product development.

Donepezil accelerates the release of PLGA microparticles via catalyzing the polymer degradation regardless of the end groups and molecular weights

Poly (lactic-co-glycolic acid) (PLGA) is one of the most successful polymers for sustained parenteral drug products in the market. However, rational selection of PLGA in the formulations is still challenging due to the lack of fundamental studies. The present study aimed to investigate the influence of donepezil (DP) on the in-vitro and in-vivo performance of PLGA sustained microspheres. Three kinds of PLGAs with different end groups and molecular weights were selected. Then DP-loaded PLGA microspheres (DP-MSs) with similar particle size, drug loading, and encapsulation efficiency were prepared using an o/w emulsion-solvent evaporation method. Laser diffraction and scanning electron microscopy showed that the prepared DP-MSs were about 35 μm and spherical in shape. Differential scanning calorimetry and X-ray diffraction indicated that DP was in an amorphous state inside the microspheres. Unexpectedly, the molecular weight and end group of PLGAs did not significantly influence the in-vitro and in-vivo performance of the DP-MSs. The gel permeation chromatography indicated that the degradation rates of PLGAs were accelerated with the incorporation of DP into the microspheres, and the molecular weight of all three kinds of PLGAs sharply dropped to about 11,000 Da within the initial three days. The basic catalysis effect induced by DP might be responsible for the accelerated degradation of PLGAs, which led to similar in-vitro release profiles of DP from different PLGA matrices. A point-to-point level A correlation between the in-vitro release and the in-vivo absorption was observed, which confirmed the accelerated release of DP from the DP-MSs in-vivo. The results indicated that the influence of DP on the degradation of PLGA should be considered when developing DP-sustained microspheres.

Synthesis, characterization, thermal stability, and in vitro and in vivo degradation study of polycaprolactone and polyglycolide block copolymers

Biodegradable polymer materials are attractive in various biomedical applications. Herein, we report a block aliphatic copolymer, polycaprolactone-block-polyglycolide (PCL-b-PGA, denoted as PCLGA), and explored the polymer composition effect on the thermal and degradation behaviors. Three copolymers with different PCL/PGA weight ratios were obtained by a two-step ring opening polymerization. The chemical structures and compositions of copolymers were studied by NMR and FT-IR. The thermal behaviors were investigated by DSC and TGA. The in vitro degradation in phosphate buffer saline and in vivo degradation as an implant in rats were evaluated and the hygroscopic rate and polymer weight loss changes were monitored in an eight-week period. PCLGA with a higher PCL composition showed a slower degradation in vitro and in vivo. These PCLGAs with different degradation rates could be used as biomedical implants for potential application in drug delivery and tissue repair.

Simultaneous Release of Aflibercept and Dexamethasone from an Ocular Drug Delivery System

PURPOSE

Intravitreal injections of anti-vascular endothelial growth factors (anti-VEGF) are the current standard of care for patients with choroidal neovascularization (CNV) secondary to age-related macular degeneration (AMD). There is a growing subset of patients that does not respond to anti-VEGF monotherapy treatment. Some patients, however, do respond to combination therapy of corticosteroids and anti-VEGF. This treatment requires monthly/bimonthly injections of anti-VEGF and semi-annual injections of corticosteroid. A drug delivery system (DDS) that simultaneously releases multiple drugs could benefit these patients by reducing the number of injections. The purpose of this study was to characterize the simultaneous release of aflibercept and dexamethasone from a biodegradable microparticle- and nanoparticle-hydrogel DDS.

METHODS

Dexamethasone-loaded nanoparticles and aflibercept-loaded microparticles were created using modified single- and double-emulsion techniques, respectively. Then, microparticles and nanoparticles were embedded into a thermoresponsive, biodegradable poly(ethylene glycol)-co-(L-lactic acid) diacrylate (PEG-PLLA-DA)-N-isopropylacrylamide (NIPAAm) hydrogel DDS. Drug release studies and characterization of DDS were conducted with varying doses of microparticles and nanoparticles.

RESULTS

The combination aflibercept-loaded microparticle- and dexamethasone-loaded nanoparticle- hydrogel (Combo-DDS) achieved a total release time of 224 days. Small decreases were seen in swelling ratio and equilibrium water content for Combo-DDS compared to monotherapy aflibercept-loaded microparticle-hydrogel DDS (AFL-DDS) and monotherapy dexamethasone-loaded nanoparticle-hydrogel DDS (DEX-DDS). Bioactivity of aflibercept was maintained in Combo-DDS compared to AFL-DDS.

CONCLUSIONS

The Combo-DDS was able to extend and control the release of both aflibercept and dexamethasone simultaneously from a single DDS. This may eliminate the need for separate dosing regiments of anti-VEGF and corticosteroids for wet AMD patients.

Storage and release of rare earth elements in microsphere-based scaffolds for enhancing osteogenesis

In osteoporosis and diabetes, it is essential to accelerate the bone repair and regeneration process. Trace rare earth elements such as lanthanum (La) ions (La³⁺) with appropriate concentrations are bioactive and can effectively regulate bone tissue performances. However, few well-established bone tissue engineering scaffolds can precisely and stably release La³⁺ to promote bone regeneration significantly. Based on the advantages of biodegradable microspheres and microsphere-based scaffolds for controlled drug release, we developed poly(lactide-co-glycolide) (PLGA)-based microsphere-based scaffolds as both three-dimensional (3D) porous scaffolds and La³⁺ storage and release systems for osteogenesis. So far, there is no study about microsphere-based scaffolds to release trace La³⁺ to induce osteogenic differentiation of bone marrow mesenchymal stromal cells (BMSCs). PLGA microspheres co-embedded with La-doped mesoporous silica (LMS) with different amounts of doped La were sintered to prepare the LMS/PLGA (LMSP) microsphere-based scaffold. The La³⁺ release behavior of LMSP can be controlled by adjusting the doping amount of La in mesoporous silica (MS). All these scaffolds possessed a 3D network architecture. With the increase of La doping, LMSP can better compensate for the pH decrease caused by PLGA degradation. The combination of MS and PLGA can avoid the cytotoxicity of MS alone. All prepared LMSP scaffolds were non-cytotoxic. After BMSCs were implanted on scaffolds, LMSP could promote cells adhesion, proliferation, and osteogenic differentiation. Among these microsphere-based scaffolds, LMSP-3 with stable and higher dose La³⁺ release behavior showed the strongest ability to enhance the osteogenesis of BMSCs. The results showed that microsphere-based scaffolds with the ability to store and stably control the release of La³⁺ could effectively improve osteogenic performance, which provides a new idea for the construction of bone tissue engineering scaffolds.

Enzymatically Crosslinked In Situ Synthesized Silk/Gelatin/Calcium Phosphate Hydrogels for Drug Delivery

Our research focuses on combining the valuable properties of silk fibroin (SF) and calcium phosphate (CaP). SF is a natural protein with an easily modifiable structure; CaP is a mineral found in the human body. Most of the new age biocomposites lack interaction between organic/inorganic phase, thus SF/CaP composite could not only mimic the natural bone, but could also be used to make drug delivery systems as well, which can ensure both healing and regeneration. CaP was synthesized in situ in SF at different pH values, and then crosslinked with gelatin (G), horseradish peroxide (HRP), and hydrogen peroxide (H₂O₂). In addition, dexamethasone phosphate (DEX) was incorporated in the hydrogel and drug delivery kinetics was studied. Hydrogel made at pH 10.0 was found to have the highest gel fraction 110.24%, swelling degree 956.32%, and sustained drug delivery for 72 h. The highest cell viability was observed for the hydrogel, which contained brushite (pH 6)-512.43%.

Development and evaluation of a novel biodegradable implants with excellent inflammatory response suppression effect by hot-melt extrusion

PURPOSE

Dexamethasone (Dex) is a widely used drug for the treatment of inflammatory and autoimmune conditions, however, long-term systemic use of Dex is associated with serious adverse effects. The objective of the present study was to develop an implantable device to avoid side effects and realize a controlled release of Dex at the implant site.

METHODS

Hydrophobic Dex was incorporated into biodegradable polyesters derived from PCL and Pluronic® L64 (PCL-Pluronic L64-PCL, PCLC) by hot-melt extrusion (HME) method to prepare Dex/PCLC implantable devices. Drug loading and encapsulation efficiency, a series of physicochemical properties, and in vivo features of the implants were studied.

RESULTS

The maximum value of the drug loading and encapsulation efficiency for the Dex/PCLC implants were up to 47% and 94%, respectively. Incorporation of Dex resulted in accelerated crystallization of PCLC, decreased the wettability, increased contact angles and viscosity, and accelerated Dex release rate and degradation rate from the implants in vivo. Moreover, Dex/PCLC implants showed excellent biocompatibility. Furthermore, the inflammatory response to the Dex/PCLC implants was less severe than that to the positive control group.

CONCLUSION

All these results suggested that Dex/PCLC implants might be a safe and controlled local drug delivery system with excellent inflammatory response suppression effect.

Local drug delivery using poly(lactic-co-glycolic acid) nanoparticles in thermosensitive gels for inner ear disease treatment

Intratympanic (IT) therapies have been explored to address several side effects that could be caused by systemic administration of steroids to treat inner ear diseases. For effective drug delivery to the inner ear, an IT delivery system was developed using poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) and thermosensitive gels to maintain sustained release. Dexamethasone (DEX) was used as a model drug. The size and zeta potential of PLGA NPs and the gelation time of the thermosensitive gel were measured. In vitro drug release was studied using a Franz diffusion cell. Cytotoxicity of the formulations was investigated using SK-MEL-31 cells. Inflammatory responses were evaluated by histological observation of spiral ganglion cells and stria vascularis in the mouse cochlea 24 h after IT administration. In addition, the biodistribution of the formulations in mouse ears was observed by fluorescence imaging using coumarin-6. DEX-NPs showed a particle size of 150.0 ± 3.2 nm in diameter and a zeta potential of −18.7 ± 0.6. The DEX-NP-gel showed a gelation time of approximately 64 s at 37 °C and presented a similar release profile and cytotoxicity as that for DEX-NP. Furthermore, no significant inflammatory response was observed after IT administration. Fluorescence imaging results suggested that DEX-NP-gel sustained release compared to the other formulations. In conclusion, the PLGA NP-loaded thermosensitive gel may be a potential drug delivery system for the inner ear.

Design, development, and characterization of an idebenone-loaded poly-ε-caprolactone intravitreal implant as a new therapeutic approach for LHON treatment

Leber's Hereditary Optic Neuropathy (LHON) is a hereditary mitochondrial neurodegenerative disease of unclear etiology and lack of available therapeutic alternatives. The main goal of the current pilot study was based on the evaluation of the feasibility and characteristics of prolonged and controlled idebenone release from a PCL intravitreal implant. The design, development, and characterization of idebenone-loaded PCL implants prepared by an homogenization/extrusion/solvent evaporation method allowed the obtention of high PY, EE and LC values. In vitro characterization was completed by the assessment of mechanical and instrumental properties. The in vitro release of idebenone from the PCL implants was assessed and the implant erosion was monitored by the mass loss and surface morphology changes. DSC was used to estimate stability and interaction among implant's components. The present work demonstrated the controlled and prolonged idebenone delivery from the PCL implants in an in vitro model. A consistent preclinical base was established, supporting the idea of idebenone-loaded PCL implants as a new strategy of long-term sustained intraocular delivery for the LHON treatment.

IGF-1-releasing PLGA nanoparticles modified 3D printed PCL scaffolds for cartilage tissue engineering

The aim of this study is to fabricate and test a 3D-printed PCL scaffold incorporating IGF-1-releasing PLGA nanoparticles for cartilage tissue engineering. IGF-1 loaded PLGA nanoparticles were produced by the double-emulsion method, and were incorporated onto 3D printed PCL scaffolds via PDA. Particle size, loading effciency (LE) and encapsulation effciency (EE) of the nanoparticles were examined. SEM, pore size, porosity, compression testing, contact angle, IGF-1 release kinetics of the composite scaffolds were also determined. For cell culture studies, CCK-8, Live/dead, MTT, GAG content and expression level of chondrocytes specific proteins and genes and HIF-1α were also tested. There was no difference of the nanoparticle size. And the LE and EE of IGF-1 in PLGA nanoparticles was about 5.53 ± 0.12% and 61.26 ± 2.71%, respectively. There was a slower, sustained release for all drug-loaded nanoparticles PLGA/PDA/PCL scaffolds. There was no difference of pore size, porosity, compressive strength of each scaffold. The contact angles PCL scaffolds were significant decreased when coated with PDA and PLGA nanoparticales. (p < .05) Live/dead staining showed more cells attached to the IGF-1 PLGA/PDA/PCL scaffolds. The CCK-8 and MTT assay showed higher cell proliferation and better biocompatibility of the IGF-1 PLGA/PDA/PCL scaffolds. (p < .05) GAG content, chondrogenic protein and gene expression level of SOX-9, COL-II, ACAN, and HIF pathway related gene (HIF-1α) were significantly higher in IGF-1 PLGA/PDA/PCL scaffolds group compared to other groups. (p < .05) IGF-1 PLGA/PDA/PCL scaffolds may be a better method for sustained IGF-1 administration and a promising scaffold for cartilage tissue engineering.

Tyrosol Derived Poly(ester-arylate)s for Sustained Drug Delivery from Microparticles

New biodegradable polymers are needed for use in drug delivery systems to overcome the high burst release, lack of sustained drug release, and acidic degradation products frequently observed in current formulations. Commercially available poly(lactide-co-glycolide) (PLGA) is often used for particle drug release formulations; however, it is often limited by its large burst release and acidic degradation products. Therefore, a biocompatible and biodegradable tyrosol-derived poly(ester-arylate) library has been used to prepare a microparticle drug delivery system which shows sustained delivery of hydrophobic drugs. Studies were performed using polymers with varying hydrophilicity and thermal properties and compared to PLGA. Various drug solubilizing cosolvents were used to load model drugs curcumin, dexamethasone, nicotinamide, and acyclovir. Hydrophobic drugs curcumin and dexamethasone were successfully loaded up to 50 weight percent (wt %), and a linear correlation between drug wt % loaded and the particle glass transition temperature (T_g) was observed. Both curcumin and dexamethasone were visible on the particle surface at 20 wt % loading and higher. By adjusting the polymer concentration during particle formation, release rates were able to be controlled. Release studies of dexamethasone loaded particles with a lower polymer concentration showed a biphasic release profile and complete release after 47 days. Particles prepared using a higher polymer concentration showed sustained release for up to 77 days. Comparably, PLGA showed a traditional triphasic release profile and complete release after 63 days. This novel tyrosol-derived poly(ester-arylate) library can be used to develop injectable, long-term release formulations capable of providing sustained drug delivery.

Dexamethasone PLGA Microspheres for Sub-Tenon Administration: Influence of Sterilization and Tolerance Studies

Many diseases affecting the posterior segment of the eye require repeated intravitreal injections with corticosteroids in chronic treatments. The periocular administration is a less invasive route attracting considerable attention for long-term therapies. In the present work, dexamethasone-loaded poly(lactic-co-glycolic) acid (PLGA) microspheres (Dx-MS) were prepared using the oil-in-water (O/W) emulsion solvent evaporation technique. MS were characterized in terms of mean particle size and particle size distribution, external morphology, polymer integrity, drug content, and in vitro release profiles. MS were sterilized by gamma irradiation (25 kGy), and dexamethasone release profiles from sterilized and non-sterilized microspheres were compared by means of the similarity factor (f₂). The mechanism of drug release before and after irradiation exposure of Dx-MS was identified using appropriate mathematical models. Dexamethasone release was sustained in vitro for 9 weeks. The evaluation of the in vivo tolerance was carried out in rabbit eyes, which received a sub-Tenon injection of 5 mg of sterilized Dx-MS (20–53 µm size containing 165.6 ± 3.6 µg Dx/mg MS) equivalent to 828 µg of Dx. No detectable increase in intraocular pressure was reported, and clinical and histological analysis of the ocular tissues showed no adverse events up to 6 weeks after the administration. According to the data presented in this work, the sub-Tenon administration of Dx-MS could be a promising alternative to successive intravitreal injections for the treatment of chronic diseases of the back of the eye.

Biodegradable calcium carbonate/mesoporous silica/poly(lactic-glycolic acid) microspheres scaffolds with osteogenesis ability for bone regeneration

Sintered microsphere-based scaffolds provide a porous structure and high-resolution spatial organization control, show great potential for bone regeneration, mainly from biodegradable biomaterials including poly(lactic-glycolic acid) (PLGA). However, acidic monomer regeneration, mainly from biodegradable biomaterials including poly(lactic-glycolic acid) (PLGA). However, acidic monomers generated by PLGA degradation tend to cause tissue inflammation, which is the central issue of PLGA-based bone regeneration scaffolds development. In this work, calcium carbonate (CC)/hexagonal mesoporous silica (HMS)/PLGA sintered microsphere-based scaffolds were developed. The scaffolds possessed a three-dimensional (3D) network structure and 30–40% porosity. The degradation results indicated that CC/HMS/PLGA scaffolds could compensate for pH increased caused by PLGA acidic byproducts effectively. Degradation results showed that CC/HMS/PLGA scaffold could effectively compensate for the pH increase caused by PLGA acidic by-products. Composite CC additives can induce the increase of adhesive proteins in the environment, which is conducive to the adhesion of cells to scaffolds. Mesenchymal stem cells (MSCs) proliferation and osteogenic differentiation were evaluated by CCK-8 assay, alkaline phosphatase (ALP) activity, ALP staining, and Alizarin Red staining. The results showed that compared with HMS/PLGA scaffolds, the proliferation of MSCs cultured with CC/HMS/PLGA scaffolds was enhanced. When cultured on the CC/HMS/PLGA scaffolds, MSCs also showed significantly enhanced ALP activity and higher calcium secretion compared with the HMS/PLGA scaffolds. CC/HMS/PLGA sintered microsphere-based scaffolds provides an attractive strategy for bone repair and regeneration with better performance.

Sintered microsphere-based scaffolds provide a porous structure and high-resolution spatial organization control, show great potential for bone regeneration, mainly from biodegradable biomaterials including poly(lactic-glycolic acid) (PLGA).

Formulation composition, manufacturing process, and characterization of poly(lactide-co-glycolide) microparticles

Injectable long-acting formulations, specifically poly(lactide-co-glycolide) (PLGA) based systems, have been used to deliver drugs systemically for up to 6 months. Despite the benefits of using this type of long-acting formulations, the development of clinical products and the generic versions of existing formulations has been slow. Only about two dozen formulations have been approved by the U.S. Food and Drug Administration during the last 30 years. Furthermore, less than a dozen small molecules have been incorporated and approved for clinical use in PLGA-based formulations. The limited number of clinically used products is mainly due to the incomplete understanding of PLGA polymers and the various variables involved in the composition and manufacturing process. Numerous process parameters affect the formulation properties, and their intricate interactions have been difficult to decipher. Thus, it is necessary to identify all the factors affecting the final formulation properties and determine the main contributors to enable control of each factor independently. The composition of the formulation and the manufacturing processes determine the essential property of each formulation, i.e., in vivo drug release kinetics leading to their respective pharmacokinetic profiles. Since the pharmacokinetic profiles can be correlated with in vitro release kinetics, proper in vitro characterization is critical for both batch-to-batch quality control and scale-up production. In addition to in vitro release kinetics, other in vitro characterization is essential for ensuring that the desired formulation is produced, resulting in an expected pharmacokinetic profile. This article reviews the effects of a selected number of parameters in the formulation composition, manufacturing process, and characterization of microparticle systems. In particular, the emphasis is focused on the characterization of surface morphology of PLGA microparticles, as it is a manifestation of the formulation composition and the manufacturing process. Also, the implication of the surface morphology on the drug release kinetics is examined. The information described here can also be applied to in situ forming implants and solid implants.

3D printing of fibre-reinforced cartilaginous templates for the regeneration of osteochondral defects

Successful osteochondral defect repair requires regenerating the subchondral bone whilst simultaneously promoting the development of an overlying layer of articular cartilage that is resistant to vascularization and endochondral ossification. During skeletal development articular cartilage also functions as a surface growth plate, which postnatally is replaced by a more spatially complex bone-cartilage interface. Motivated by this developmental process, the hypothesis of this study is that bi-phasic, fibre-reinforced cartilaginous templates can regenerate both the articular cartilage and subchondral bone within osteochondral defects created in caprine joints. To engineer mechanically competent implants, we first compared a range of 3D printed fibre networks (PCL, PLA and PLGA) for their capacity to mechanically reinforce alginate hydrogels whilst simultaneously supporting mesenchymal stem cell (MSC) chondrogenesis in vitro. These mechanically reinforced, MSC-laden alginate hydrogels were then used to engineer the endochondral bone forming phase of bi-phasic osteochondral constructs, with the overlying chondral phase consisting of cartilage tissue engineered using a co-culture of infrapatellar fat pad derived stem/stromal cells (FPSCs) and chondrocytes. Following chondrogenic priming and subcutaneous implantation in nude mice, these bi-phasic cartilaginous constructs were found to support the development of vascularised endochondral bone overlaid by phenotypically stable cartilage. These fibre-reinforced, bi-phasic cartilaginous templates were then evaluated in clinically relevant, large animal (caprine) model of osteochondral defect repair. Although the quality of repair was variable from animal-to-animal, in general more hyaline-like cartilage repair was observed after 6 months in animals treated with bi-phasic constructs compared to animals treated with commercial control scaffolds. This variability in the quality of repair points to the need for further improvements in the design of 3D bioprinted implants for joint regeneration. STATEMENT OF SIGNIFICANCE: Successful osteochondral defect repair requires regenerating the subchondral bone whilst simultaneously promoting the development of an overlying layer of articular cartilage. In this study, we hypothesised that bi-phasic, fibre-reinforced cartilaginous templates could be leveraged to regenerate both the articular cartilage and subchondral bone within osteochondral defects. To this end we used 3D printed fibre networks to mechanically reinforce engineered transient cartilage, which also contained an overlying layer of phenotypically stable cartilage engineered using a co-culture of chondrocytes and stem cells. When chondrogenically primed and implanted into caprine osteochondral defects, these fibre-reinforced bi-phasic cartilaginous grafts were shown to spatially direct tissue development during joint repair. Such developmentally inspired tissue engineering strategies, enabled by advances in biofabrication and 3D printing, could form the basis of new classes of regenerative implants in orthopaedic medicine.

Intra-Articular injection of acid-sensitive stearoxyl-ketal-dexamethasone microcrystals for long-acting arthritis therapy

Despite advances in treatment of chronic arthritis, there is still a strong need for the development of long-acting formulations that can enable local and sustained drug release at the inflamed tissues. In this work, we fabricated microcrystals of an acid-sensitive stearoxyl-ketal-dexamethasone prodrug for treatment of arthritis. Microcrystals of the prodrug with two sizes were successfully engineered and showed pH-dependent hydrolysis kinetics in vitro. In a collagen-induced arthritis rat model, we evaluated the influence of particle size and injection dose on anti-inflammatory effect after intra-articular injection. Such prodrug demonstrated long-acting anti-arthritis effects with good safety. Our results indicate ketal-based prodrugs are promising for the development of long-acting injectables and may stimulate the development of new treatments for chronic diseases.

Fabrication of chitosan/polyvinylpyrrolidone hydrogel scaffolds containing PLGA microparticles loaded with dexamethasone for biomedical applications

One of the most effective approaches for treatment of chronic rhinosinusitis is the use of hydrogel scaffolds with the sustained release of a given required drug. With this in mind, first, we synthesized and characterized poly (lactide-co-glycolide) (PLGA) micro and nano particles loaded with dexamethasone (DEX). We observed a 7-day release of DEX from nanoparticles, while the microparticles showed a 22-day release profile. Due to their slower rate of release, the PLGA microparticles loaded with DEX (PLGADEX microparticles) were specifically chosen for this study. As a second step, chitosan/polyvinylpyrrolidone (PVP) based hydrogels were prepared in various weight ratios and the PLGADEX microparticles were optimized in their structure based on variable gelation times. The morphological studies showed PLGADEX microparticles homogenously dispersed in the hydrogels. Moreover, the effect of weight ratio in the presence and absence of optimum percentage of PLGADEX microparticles was studied. The resultant hydrogels demonstrated a range of advantages, including good mechanical strength, porous morphology, amorphous structure, high swelling ratio, controlled biodegradability rate, and antibacterial activity. Additionally, a cytotoxicity analysis confirmed that the hydrogel scaffolds do not have adverse effects on the cells; our release studies in the hydrogel with the highest PVP content also showed 80% release after 30 days. Based on these results we were able to predict and control some of the mechanical properties, including the microstructure of the scaffolds, as well as the drug release, by optimizing the polymers - microparticle concentration, plus their resulting interactions. This optimized hydrogel can become part of a suitable alternative for treatment of allergic rhinitis and chronic sinusitis.

The sustained release of dexamethasone from TiO2 nanotubes reinforced by chitosan to enhance osteoblast function and anti-inflammation activity

Controlling macrophage response to biomaterials is critical for the reduction of inflammation after implantation. Here we designed a sustained release system from TiO₂ nanotubes (TNTs) to improve osteogenesis on titanium implants with anti-inflammatory properties. TNTs (around 70 nm diameter) were first fabricated on titanium surfaces by anodization, directly filled with the anti-inflammatory drug, dexamethasone (DEX) and then covered by chitosan (CHI) multilayer films. Primary osteoblast and macrophage (RAW 264.7) cells were cultured on untreated and treated titanium surfaces in vitro. Osteoblasts grown on CHI-coated Dex-filled TNTs surfaces displayed higher alkaline phosphatase (ALP) and mineralization, which was consistent with qRT-PCR analysis of osteoblastic genes including collagen type I (Col I), osteocalcin (OCN), osteopontin (OPN) and runt related transcription factor 2 (Runx2). In contrast, protein levels of nitric oxide (NO) and proinflammatory cytokines (TNF-α and IL-1β) from macrophages on Dex-filled TNTs, CHI-coated TNTs and CHI-coated Dex-filled TNTs were significantly lower, especially on CHI-coated Dex-filled TNTs surfaces compared to levels on titanium and TNTs. These results indicate that CHI-coated Dex-filled TNTs enhanced osteoblast differentiation and decreased the inflammatory response of macrophages. The approach presented here provides new insight into the modification of TNTs for the development of titanium-based implants.

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.

An efficient functionalization of dexamethasone-loaded polymeric scaffold with [3-(2,3-epoxypropoxy)-propyl]-trimethoxysilane coupling agent for bone regeneration: Synthesis, characterization, and in vitro evaluation

In this study, dexamethasone-loaded gelatin–starch scaffolds were fabricated by the freeze-drying technique under different cooling temperatures and polymeric compositions. The constructs were modified via [3-(2,3-epoxypropoxy)-propyl]-trimethoxysilane coupling agent in order to produce a bioactive network structure for bone tissue engineering applications. Herein, the synergistic effect of [3-(2,3-epoxypropoxy)-propyl]-trimethoxysilane and dexamethasone was examined on the bioactivity and osteogenic behavior of scaffolds. Based on scanning electron microscopy micrographs, more fine pores were formed at higher freezing temperatures. The prepared microstructure at a rapid freezing rate resulted in diminished mechanical properties and a greater level of swelling and durability compared with a slow freezing rate. According to the acquired results, the mechanical strength decreased, while both absorption capacity and mass loss rate increased as a function of starch addition. Furthermore, the enhancement of hydrophilicity and reduction of mechanical stability enhanced the dexamethasone release levels. In addition, the synthesized constructs confirmed the positive effect of [3-(2,3-epoxypropoxy)-propyl]-trimethoxysilane and dexamethasone on biomimetic mineralization of the scaffolds. Supporting the cellular adhesion and proliferation alongside the expression of alkaline phosphatase, especially in the presence of dexamethasone, was the other advantage of synthetic scaffolds as a bone reconstructive substitute. Accordingly, drug-loaded hybrid constructs seem to be promising for further preclinical and clinical investigations in bone tissue engineering.

Smart Hydrogel-Based DVDMS/bFGF Nanohybrids for Antibacterial Phototherapy with Multiple Damaging Sites and Accelerated Wound Healing

Burn infection is one of the commonest causes of death in severely burned patients. Developing multifunctional biological nanomaterials has a great significance for the comprehensive treatment of burn infection. In this paper, we developed a hydrogel-based nanodelivery system with antibacterial activity and skin regeneration function, which was used for photodynamic antimicrobial chemotherapy (PACT) in the treatment of burns. The treatment system is mainly composed of porphyrin photosensitizer sinoporphyrin sodium (DVDMS) and poly(lactic-co-glycolic acid) (PLGA)-encapsulated basic fibroblast growth factor (bFGF) nanospheres that are embedded in carboxymethyl chitosan (CMCS)-sodium alginate to form CSDP hybrid hydrogel. We systematically evaluated the inherent antibacterial performance, rheological properties, fluorescence imaging, and biocompatibility of the CSDP nanosystem. Under mild photoirradiation (30 J/cm², 5 min), 10 μg/mL CSDP showed excellent antibacterial and anti-biofilm activities, which eradicated almost 99.99% of Staphylococcus aureus and multidrug-resistant (MDR) S. aureus in vitro. KEGG analysis identified that multiple signaling pathways were changed in MDR S. aureus after PACT. In the burn-infection model, CSDP-PACT successfully inhibited bacteria growth and concurrently promoted wound healing. Moreover, several regenerative factors were increased and some proinflammatory factors were reduced in the burn wounds of CSDP hydrogel treatment. These results suggest that the multifunctional CSDP hydrogel is a portable, light-triggered, antibacterial theranostic-platform and CSDP-PACT provides a promising strategy or the mechanically based synergistic treatment of burn infections.

Novel optimized biopolymer-based nanoparticles for nose-to-brain delivery in the treatment of depressive diseases

A valid option to bypass the obstacle represented by the blood–brain barrier (BBB) in brain delivery is the use of the unconventional intranasal route of administration. The treatment of depressive diseases, resulting from the depletion of a neurotransmitter in the inter-synaptic space, such as serotonin, is indirectly treated using molecules that can permeate the BBB unlike the latter. In the present article, a set of nanovectors were produced using a mucoadhesive biopolymer, i.e. alginate (Alg). Optimizing the reaction, polymeric nanoparticles having diameter of 30–70 nm were produced, and water stable multi-walled carbon nanotubes functionalized (MWCNT-COOH)/Alg complexes were obtained. These nanovectors were loaded with serotonin, evaluating drug loading/release. By means of Raman microscopy, the cellular internalization of the (MWCNT-COOH)/Alg complex was demonstrated. A complete biocompatibility on neuronal cells was proved for the whole set of nanovectors. Finally, a method of self-administration was tested, which involves the use of a household apparatus, such as an aerosol machine, observing a fine particulate, able to deliver the nanovectors through the nose.

A valid option to bypass the obstacle represented by the blood–brain barrier (BBB) in brain delivery is the use of the unconventional intranasal route of administration.

Curcumin-loaded zeolite as anticancer drug carrier: effect of curcumin adsorption on zeolite structure

In this work we used a combination of different techniques to investigate the adsorption properties of curcumin by zeolite type A for potential use as an anticancer drug carrier. Curcumin is a natural water-insoluble drug that has attracted great attention in recent years due to its potential anticancer effect in suppressing many types of cancers, while showing a synergistic antitumor effect with other anticancer agents. However, curcumin is poorly soluble in aqueous solutions leading to the application of high drug dosage in oral formulations. Zeolites, inorganic crystalline aluminosilicates with porous structure on the nano- and micro-scale and high internal surface area, can be useful as pharmaceutical carrier systems to encapsulate drugs with intrinsic low aqueous solubility and improve their dissolution. Here, we explore the use of zeolite type A for encapsulation of curcumin, and we investigate its surface properties and morphology, before and after loading of the anticancer agent, using scanning electron microscopy (SEM), powder X-ray diffraction (XRD), differential scanning calorimetry (DSC), and UV-vis spectroscopy. Results are used to assess the loading efficiency of zeolite type A towards curcumin and its structural stability after loading.

Dexamethasone Degradation in Aqueous Medium and Implications for Correction of In Vitro Release from Sustained Release Delivery Systems

The in vitro drug release in an aqueous medium is a critical performance metric for a sustained release drug product. During long-term release studies, drugs may degrade in the release medium, and such degradation can lead to errors in drug release quantitation. Using dexamethasone as a model drug and LC-MS/MS methods employing dexamethasone-d₄ as an internal standard, this study identified that dexamethasone can degrade into 13 major degradation products in phosphate buffered saline (PBS) as a function of time, temperature (25, 37, and 45°C), and light exposure. A putative scheme for dexamethasone degradation pathways in PBS has been proposed. In proof-of-concept studies, the analytical method was used to quantitate dexamethasone and its degradation products during in vitro release studies with sustained release dexamethasone-poly(D,L-lactide-co-glycolide) (PLGA) implants incubated in phosphate buffer saline (PBS). Further, mathematical approaches were developed to estimate drug release from implants after accounting for drug degradation in PBS. The LC-MS/MS analytical method and the mathematical approaches developed could be used for assessing the stability and/or release of dexamethasone during manufacturing, storage, and use of various dosage forms.

Optimising poly(lactic-co-glycolic acid) microparticle fabrication using a Taguchi orthogonal array design-of-experiment approach

The objective of this study was to identify, understand and generate a Taguchi orthogonal array model for the formation of 10-50 μm microparticles with applications in topical/ocular controlled drug delivery. Poly(lactic-co-glycolic acid) (PLGA) microparticles were fabricated by the single emulsion oil-in-water method and the particle size was characterized using laser diffraction and scanning electronic microscopy (SEM). Sequential Taguchi L12 and L18 orthogonal array (OA) designs were employed to study the influence of ten and eight parameters, respectively, on microparticle size (response). The first optimization step using the L12 design showed that all parameters significantly influenced the particle size of the prepared PLGA microparticles with exception of the concentration of poly(vinyl alcohol) (PVA) in the hardening bath. The smallest mean particle size obtained from the L12 design was 54.39 μm. A subsequent L18 design showed that the molecular weight of PLGA does not significantly affect the particle size. An experimental run comprising of defined parameters including molecular weight of PLGA (89 kDa), concentration of PLGA (20% w/v), concentration of PVA in the emulsion (0.8% w/v), solvent type (ethyl acetate), organic/aqeuous phase ratio (1:1 v/v), vortexing speed (9), vortexing duration (60 seconds), concentration of PVA in hardening bath (0.8% w/v), stirring speed of hardening bath (1200 rpm) and solvent evaporation duration (24 hours) resulted in the lowest mean particle size of 23.51 μm which was predicted and confirmed by the L18 array. A comparable size was demonstrated during the fabrication of BSA-incorporated microparticles. Taguchi OA design proved to be a valuable tool in determining the combination of process parameters that can provide the optimal condition for microparticle formulation. Taguchi OA design can be used to correctly predict the size of microparticles fabricated by the single emulsion process and can therefore, ultimately, save time and costs during the manufacturing process of drug delivery formulations by minimising experimental runs.

Nanoparticle-based model of anti-inflammatory drug releasing LbL coatings for uncemented prosthesis aseptic loosening prevention

Introduction

The only treatment for aseptic loosening is the replacement of the prosthesis through revision surgery. A preventive approach, achieved through anti-inflammatory drugs released from the device, has shown to be a viable strategy; however, the performance of these devices is not yet satisfactory thus further improvements are necessary.

Methods

We used titanium nanoparticles as a model for implant surfaces and developed a coating containing dexamethasone (DEX) using layer-by-layer deposition.

Results

The amount of deposited drug depended on the number of layers and the release was sustained for months. The efficiency of the released DEX in reducing inflammation markers (tumor necrosis factor alpha and IL-6) produced by human monocytes and macrophages was similar to the pure drug at the same concentration without negative impacts on the viability and morphology of these cells.

Conclusion

These coatings were not inferior to medical grade titanium (the standard material used in uncemented devices) regarding their ability to sustain osteoblasts and fibroblasts growth.

Modeling a pH-sensitive Zein-co-acrylic acid hybrid hydrogels loaded 5-fluorouracil and rutin for enhanced anticancer efficacy by oral delivery

The combination of natural and synthetic polymeric materials grafted hydrogels offer great potential as oral therapeutic systems because of its intrinsic biocompatibility, biodegradability, protect labile drugs from metabolism and controlled release properties. Hence, in the present study, we aimed to prepare and optimize oral delivered pH-responsive Zein-co-acrylic acid hydrogels incorporated with 5-fluorouracil (5-Fu) and rutin (Ru) for effective anticancer activity with less toxicity. In this study, graft polymerization technique is adopted to formulate hydrogels with various ratios of Zein, acrylic acid, N, N-methylene bisacrylamide, and ammonium persulphate as an initiator. The optimized formulation was identified based on the cross-linking, chemical interactions, intrinsic viscosity (η), dynamic swelling (Q) at pH 1.2, diffusion coefficient (D), sol-gel fraction (%), and porosity (%). The selected optimized formulation has shown significant improvement in drugs loading and encapsulation efficiency, releasing at pH 1.2 and pH 7.4. Drug release kinetics studies confirmed the controlled release properties of hydrogels. Hydrogels were porous and the drug loading of 5-Fu and Ru was found to be 12.13% and 10.86%, respectively, whereas encapsulation efficiency of 5-Fu and Ru was 89.35% and 81.47%, respectively. Furthermore, form the in vitro cytotoxic screening, it was found that 52.5 µg mL-1 5-Fu and Ru-loaded hydrogel impacted 50% of cell death at 24 h, there by significantly arresting the proliferation of MDA-MB-231 and MCF-7 breast cancer cell lines. Altogether, the optimized pH-responsive hydrogels make them favorable carrier for anticancer drugs for oral delivery.

Anti-IL-6 eluting immunomodulatory biomaterials prolong skin allograft survival

A primary goal in the management of burn wounds is early wound closure. The use of skin allografts represents a lifesaving strategy for severe burn patients, but their ultimate rejection limits their potential efficacy and utility. IL-6 is a major pleiotropic cytokine which critically links innate and adaptive immune responses. Here, we devised anti-IL-6 receptor eluting gelatin methacryloyl (GelMA) biomaterials (GelMA/anti-IL-6), which were implanted at the interface between the wound beds and skin allografts. Our visible light crosslinked GelMA/anti-IL-6 immunomodulatory biomaterial (IMB) demonstrated a stable kinetic release profile of anti-IL-6. In addition, the incorporation of anti-IL-6 within the GelMA hydrogel had no effect on the mechanical properties of the hydrogels. Using a highly stringent skin transplant model, the GelMA/anti-IL-6 IMB almost doubled the survival of skin allografts. The use of GelMA/anti-IL-6 IMB was far superior to systemic anti-IL-6 receptor treatment in prolonging skin allograft survival. As compared to the untreated control group, skin from the GelMA/anti-IL-6 IMB group contained significantly fewer alloreactive T cells and macrophages. Interestingly, the environmental milieu of the draining lymph nodes (DLNs) of the mice implanted with the GelMA/anti-IL-6 IMB was also considerably less pro-inflammatory. The percentage of CD4⁺ IFNγ⁺ cells was much lower in the DLNs of the GelMA/anti-IL-6 IMB group in comparison to the GelMA group. These data highlight the importance of localized immune delivery in prolonging skin allograft survival and its potential utility in treating patients with severe burns.

Development and Characterization of Olanzapine Loaded Poly(lactide-co-glycolide) Microspheres for Depot Injection: In vitro and In vivo Release Profiles

Purpose:

The purpose of this study was to develop a new PLGA based microsphere formulation aimed to release the olanzapine for the period of one month which will result in increased compliance.

Methods:

Microspheres loaded with olanzapine were prepared using oil in water emulsion and solvent evaporation technique. The microspheres were characterized by surface morphology, shape, size, bulk density, encapsulation efficiency, and Fourier transform infrared spectrometry. In vitro release studies were performed in phosphate buffer at 37°C and in vivo studies were conducted on male Sprague- Dawley rats.

Results:

The morphological results indicated that microspheres produced were having a smooth surface, spherical shape and the size in the range from 9.71 to 19.90 μm mean diameter. Encapsulation efficiency of olanzapine loaded microspheres was in the range of 78.53 to 96.12% and was affected by changing the ratio of lactic to glycolic acid in copolymer PLGA. The properties of PLGA and other formulation parameters had a significant impact on in vitro and in vivo release of drug from microspheres. In vitro release kinetics revealed that release of drug from microspheres is by both non-Fickian diffusion and erosion of PLGA polymer. In vivo data indicated an initial burst release and then sustained release depending on properties of PLGA, microsphere size, and bulk density.

Conclusion:

This study indicates that microsphere formulations developed with PLGA (75:25) and PLGA (85:15) have provided a sufficient steady release of drug for at least 30 days and can be potential candidates for 30-day depot injection drug delivery of olanzapine.

Controlled release of dexamethasone from poly(vinyl alcohol) hydrogel

This study investigated a chemically crosslinked poly(vinyl alcohol) (PVA) hydrogel controlled drug delivery system to deliver the anti-inflammatory drug dexamethasone (DEX). The PVA hydrogels, with different crosslinking densities, were characterized by swelling studies, electron scanning microscopy, viscosity, Fourier transform infrared spectroscopy (FTIR) and in vitro release assessment. Increasing crosslinking density slowed and decreased swelling and water absorption. FTIR analysis suggested DEX has possible interactions with the crosslinker and the PVA polymer. In vitro release of DEX from PVA hydrogels was sustained for 33 days and appeared to fit the Higuchi and Korsmeyer-Peppas models. This work indicates the likelihood of PVA hydrogel as a controlled drug release system for DEX for anti-inflammatory uses.

Anti-inflammatory drug-eluting implant model system to prevent wear particle-induced periprosthetic osteolysis

BACKGROUND

Aseptic loosening, as a consequence of an extended inflammatory reaction induced by wear particles, has been classified as one of the most common complications of total joint replacement (TJR). Despite its high incidence, no therapeutical approach has yet been found to prevent aseptic loosening, leaving revision as only effective treatment. The local delivery of anti-inflammatory drugs to modulate wear-induced inflammation has been regarded as a potential therapeutical approach to prevent aseptic-loosening.

METHODS

In this context, we developed and characterized anti-inflammatory drug-eluting TiO2 surfaces, using nanoparticles as a model for larger surfaces. The eluting surfaces were obtained by conjugating dexamethasone to carboxyl-functionalized TiO2 particles, obtained by using either silane agents with amino or mercapto moieties.

RESULTS

Zeta potential measurements, thermogravimetric analysis (TGA) and drug release results suggest that dexamethasone was successfully loaded onto the TiO2 particles. Release was pH dependent and greater amounts of drug were observed from amino route functionalized surfaces. The model-system was then tested for its cytotoxic and anti-inflammatory properties in LPS-stimulated macrophages. Dexamethasone released from amino route functionalized surfaces TiO2 particles was able to decrease LPS-induced nitric oxide (NO) and TNF-a production similarly to pure DEX at the same concentration; DEX released from mercapto route functionalized surfaces was at a too low concentration to be effective.

CONCLUSION

Dexamethasone released from amino functionalized titanium can offer the possibility of preventing asepting loosening of joint replacement devices.