A modified double-emulsion method for the preparation of daunorubicin-loaded polymeric nanoparticle with enhancedin vitroanti-tumor activity

Toward the scale-up production of polymeric nanotherapeutics for cancer clinical trials

Nanotherapeutics have gained significant attention for the treatment of numerous cancers, primarily because they can accumulate in and/or selectively target tumors leading to improved pharmacodynamics of encapsulated drugs. The flexibility to engineer the nanotherapeutic characteristics including size, morphology, drug release profiles, and surface properties make nanotherapeutics a unique platform for cancer drug formulation. Polymeric nanotherapeutics including micelles and dendrimers represent a large number of formulation strategies developed over the last decade. However, compared to liposomes and lipid-based nanotherapeutics, polymeric nanotherapeutics have had limited clinical translation from the laboratory. One of the key limitations of polymeric nanotherapeutics formulations for clinical translation has been the reproducibility in preparing consistent and homogeneous large-scale batches. In this review, we describe polymeric nanotherapeutics and discuss the most common laboratory and scale-up formulation methods, specifically those proposed for clinical cancer therapies. We also provide an overview of the major challenges and opportunities for scaling polymeric nanotherapeutics to clinical-grade formulations. Finally, we will review the regulatory requirements and challenges in advancing nanotherapeutics to the clinic.

Melanin Nanoparticles Obtained from Preformed Recombinant Melanin by Bottom-Up and Top-Down Approaches

Melanin is an insoluble, amorphous polymer that forms planar sheets that aggregate naturally to create colloidal particles with several biological functions. Based on this, here, a preformed recombinant melanin (PRM) was utilized as the polymeric raw material to generate recombinant melanin nanoparticles (RMNPs). These nanoparticles were prepared using bottom-up (nanocrystallization-NC, and double emulsion-solvent evaporation-DE) and top-down (high-pressure homogenization-HP) manufacturing approaches. The particle size, Z-potential, identity, stability, morphology, and solid-state properties were evaluated. RMNP biocompatibility was determined in human embryogenic kidney (HEK293) and human epidermal keratinocyte (HEKn) cell lines. RMNPs prepared by NC reached a particle size of 245.9 ± 31.5 nm and a Z-potential of -20.2 ± 1.56 mV; 253.1 ± 30.6 nm and -39.2 ± 0.56 mV compared to that obtained by DE, as well as RMNPs of 302.2 ± 69.9 nm and -38.6 ± 2.25 mV using HP. Spherical and solid nanostructures in the bottom-up approaches were observed; however, they were an irregular shape with a wide size distribution when the HP method was applied. Infrared (IR) spectra showed no changes in the chemical structure of the melanin after the manufacturing process but did exhibit an amorphous crystal rearrangement according to calorimetric and PXRD analysis. All RMNPs presented long stability in an aqueous suspension and resistance to being sterilized by wet steam and ultraviolet (UV) radiation. Finally, cytotoxicity assays showed that RMNPs are safe up to 100 μg/mL. These findings open new possibilities for obtaining melanin nanoparticles with potential applications in drug delivery, tissue engineering, diagnosis, and sun protection, among others.

A novel combination for the treatment of small cell lung cancer: Active targeted irinotecan and stattic co-loaded PLGA nanoparticles

Polymeric nanoparticles are widely used drug delivery systems for cancer treatment due to their properties such as ease of passing through biological membranes, opportunity to modify drug release, specifically targeting drugs to diseased areas, and potential of reducing side effects. Here, we formulated irinotecan and Stattic co-loaded PLGA nanoparticles targeted to small cell lung cancer. Nanoparticles were successfully conjugated with CD56 antibody with a conjugation efficiency of 84.39 ± 1.01%, and characterization of formulated nanoparticles was conducted with in-vitro and in-vivo studies. Formulated particles had sizes in the range of 130-180 nm with PDI values smaller than 0.3. Encapsulation and active targeting of irinotecan and Stattic resulted in increased cytotoxicity and anti-cancer efficiency in-vitro. Furthermore, it was shown with ex-vivo biodistribution studies that conjugated nanoparticles were successfully targeted to CD56-expressing SCLC cells and distributed mainly to tumor tissue and lungs. Compliant with our hypothesis and literature, the STAT3 pathway was successfully inhibited with Stattic solution and Stattic loaded nanoparticles. Additionally, intravenous injection of conjugated co-loaded nanoparticles resulted in decreased side effects and better anti-tumor activity than individual solutions of drugs in SCLC tumor-bearing mice. These results may indicate a new treatment option for clinically aggressive small cell lung cancer.

Evaluation of Nanoparticles with 5-Fluorouracil and Chloroquine on Acanthamoeba castellanii activity

Acanthamoeba is opportunistic pathogens that cause vision-threatening Acanthamoeba keratitis (AK). Previous studies proposed the use of chloroquine (CQ) and 5-fluorouracil (5FU) as anti-Acanthamoeba agents. The objective of this study was to determine the benefit of using 5FU and CQ nanoparticles (NP) formulations against A. castellanii that belonging to the T4 genotype and evaluate their anti-Acanthamoebic characteristic. Triplicate batches of 5FU nanoparticles (5FU-NP) were synthesized by using a modified nanoprecipitation method, while CQ anoparticles (CQ-NP) synthesized using a modified double emulsion method. The synthesized nanoparticles were subjected to biological assays to investigate their amoebicidal, amoebistatic, anti-encystation, and anti-excystation effects against A. castellanii, as well as cell cytotoxicity. Cytotoxicity assays were performed using human keratinocyte cells (HaCat) to determine the effect of CQ and 5FU nanoformulations on host cells. 5FU-NP with a concentration of 60µM showed significant inhibition to amoeba binding into human cell lines and remarkable prevention mainly during the encystation stage. Moreover, 5FU-NP resulted in less cytotoxicity and pathogenicity when compared with the free 5FU. On the other hand, CQ and CQ-NP, at the same concentration, showed poor inhibition to amoeba binding into human cells and insignificant prevention to encystation stage. Moderate human cells damage was resulted following their treatment with CQ and CQ-NP. In conclusion, 5FU may have the potential as an antiamoebic agent against Acanthamoeba spp. preferably as a nanoformulation to enhance its activity and reduce its cytoxicity.

Formulation of drug-loaded oligodepsipeptide particles with submicron size

The size of particulate carriers is key to their transport and distribution in biological systems, and needs to be tailored in the higher submicron range to enable follicular uptake for dermal treatment. Oligodepsipeptides are promising nanoparticulate carrier systems as they can be designed to exhibit enhanced interaction with drug molecules. Here, a fabrication scheme for drug-loaded submicron particles from oligo[3-(S)-sec-butylmorpholine-2,5-dione]diol (OBMD) is presented based on an emulsion solvent evaporation method with cosolvent, surfactant, and polymer concentration as variable process parameters. The particle size (300-950 nm) increased with lower surfactant concentration and higher oligomer concentration. The addition of acetone increased the particle size at low surfactant concentration. Particle size remained stable upon the encapsulation of models compounds dexamethasone (DXM) and Nile red (NR), having different physicochemical properties. DXM was released faster compared to NR due to its higher water solubility. Overall, the results indicated that both drug-loading and size control of OBMD submicron particles can be achieved. When applied on porcine ear skin samples, the NR-loaded particles have been shown to allow NR penetration into the hair follicle and the depth reached with the 300 nm particles was comparable to the one reached with the cream formulation. A potential benefit of the particles compared to a cream is their sustained release profile.

Polymer Nanoparticles and Nanomotors Modified by DNA/RNA Aptamers and Antibodies in Targeted Therapy of Cancer

Polymer nanoparticles and nano/micromotors are novel nanostructures that are of increased interest especially in the diagnosis and therapy of cancer. These structures are modified by antibodies or nucleic acid aptamers and can recognize the cancer markers at the membrane of the cancer cells or in the intracellular side. They can serve as a cargo for targeted transport of drugs or nucleic acids in chemo- immuno- or gene therapy. The various mechanisms, such as enzyme, ultrasound, magnetic, electrical, or light, served as a driving force for nano/micromotors, allowing their transport into the cells. This review is focused on the recent achievements in the development of polymer nanoparticles and nano/micromotors modified by antibodies and nucleic acid aptamers. The methods of preparation of polymer nanoparticles, their structure and properties are provided together with those for synthesis and the application of nano/micromotors. The various mechanisms of the driving of nano/micromotors such as chemical, light, ultrasound, electric and magnetic fields are explained. The targeting drug delivery is based on the modification of nanostructures by receptors such as nucleic acid aptamers and antibodies. Special focus is therefore on the method of selection aptamers for recognition cancer markers as well as on the comparison of the properties of nucleic acid aptamers and antibodies. The methods of immobilization of aptamers at the nanoparticles and nano/micromotors are provided. Examples of applications of polymer nanoparticles and nano/micromotors in targeted delivery and in controlled drug release are presented. The future perspectives of biomimetic nanostructures in personalized nanomedicine are also discussed.

Functionalized Polycaprolactone/Hydroxyapatite Composite Microspheres for Promoting Bone Consolidation in a Rat Distraction Osteogenesis Model

Distraction osteogenesis (DO) is an ideal model to study bone regeneration. The major limitation is the relatively long period required for new bone consolidation. Here, we investigated whether the application of polycaprolactone (PCL) and hydroxyapatite (HA) composite microspheres could enhance bone formation in DO. Pure PCL microspheres and composite PCL and 10% HA microspheres were synthesized. Bone mesenchymal stem cells isolated from green fluorescent protein rats (GFP-rBMSCs) were cultured with microspheres in a rotary bioreactor system. Scanning electron microscopy was used to examine the microstructures. Osteogenic differentiation of rBMSCs was confirmed. Moreover, PCL/HA (20 mg) and PCL (20 mg) were locally administered into the distraction gap in the rat DO model toward the end of the distraction period. Imaging detection, mechanical and histological examinations were performed to assess the quality of the 4-week regenerates. Results showed that the microspheres were of uniform size and monodisperse. After incubation with rBMSCs in culture, PCL/HA microspheres showed a better ability for cell adhesion and osteogenic differentiation compared with PCL microspheres. In vivo, bone volume/total tissue volume, bone mineral density, and mechanical properties of the new callus were significantly higher in the PCL/HA group compared with the PCL group. Histological analyses confirmed improved bone formation and vascularization in PCL/HA group. We presented an effective protocol for the generation of functionalized microspheres and demonstrated implantation of PCL/HA microspheres into the distraction regenerate could significantly enhance bone consolidation. Thus, the application of PCL/HA composite microspheres may be a novel approach for promoting bone regeneration. This article is protected by copyright. All rights reserved © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:961-971, 2020.

Comparative study of cilnidipine loaded PLGA nanoparticles: process optimization by DoE, physico-chemical characterization and in vivo evaluation

Cilnidipine (CND) is known to have low oral bioavailability due to its poor aqueous solubility, low dissolution rate, and high gut wall metabolism. In the present study, CND-loaded PLGA nanoparticles (CND-PLGA-NPs) were prepared with two different grades of PLGA (50:50 and 75:25) by design of experiment. Critical factors affecting particle size and entrapment efficiency (EE%) were assessed by mixed design approach, comprising of Plackett-Burman design followed by rotatable central composite design. Particle size, PDI, zeta potential, and EE% of optimized formulations of CND-PLGA(50:50)-NPs and CND-PLGA(75:25)-NPs were 211.6 ± 1.8 nm, 0.21 ± 0.05, - 15.1 ± 1.6 mV, and 85.9 ± 1.5% and 243.5 ± 2.4 nm, 0.23 ± 0.06, -19.6 ± 1.3 mV, and 92.0 ± 1.2% respectively. No significant changes were observed in physical stability of NPs when stored at 25 °C/60% RH over a period of 3 months. Pharmacokinetic studies revealed that F_abs of CND-PLGA(50:50)-NPs (1.15) and CND-PLGA(75:25)-NPs (2.23) were significantly higher than the free CND (0.26). The C_max and AUC_0-∞ of CND-PLGA(50:50)-NPs (787.42 ± 27.38 ng/mL and 9339.37 ± 252.38 ng/ml × h) and CND-PLGA(75:25)-NPs (803.49 ± 19.63 ng/mL and 18,153.34 ± 543.05 ng/ml × h) were significantly higher (p ˂ 0.0001) compared with free CND (367.69 ± 47.22 ng/mL and 2107.95 ± 136.40 ng/ml × h). MRT_Oral of CND-PLGA(50:50)-NPs (33.36 ± 0.48 h) and CND-PLGA(75:25)-NPs (48.37 ± 0.61 h) were significantly higher (p ˂ 0.0001) compared with free CND (4.69 ± 0.58 h). CND-PLGA-NPs can provide higher and sustained plasma drug levels of CND and be effective in antihypertensive therapy. Graphical abstract.

Improved therapeutic efficacy of quercetin-loaded polymeric nanoparticles on triple-negative breast cancer by inhibiting uPA

Triple negative breast cancer (TNBC) is one kind of breast cancer that demonstrates highly aggressive tumor biology. The high heterogeneity of TNBC makes its individual clinical treatment extremely blind and limited, which also introduces more challenges into the diagnosis and treatment of diseases. Urokinase-type plasminogen activator (uPA) is a high level marker for breast cancer, which mediates tumor growth and metastasis. Quercetin is a plant-derived flavonoid in many plants, which inhibits uPA and has low bioavailability and mediocre pharmaceutical efficacy. Thus, we herein developed polymeric nanoparticulate systems from PLGA-TPGS (Qu-NPs) for quercetin oral delivery and evaluated the anticancer effect of this formulation on TNBC in vitro and in vivo. Qu-NPs have a uniform spherical morphology with a mean diameter of 198.4 ± 7.8 nm and good drug loading capacity (8.1 ± 0.4%). Moreover, Qu-NPs exhibited significantly improved inhibition on the growth and metastasis in TNBC cells. Following oral gavage, a remarkable antitumor effect of Qu-NPs on 4T1-bearing mice was observed with a tumor inhibition ratio of 67.88% and fewer lung metastatic colonies. Furthermore, the inhibitory effect of quercetin on the migration of uPA knockdown MDA-MB231 cells was greatly attenuated. Together, Qu-NPs improved the significant antitumor and antimetastatic effects by inhibiting uPA, which provides a new strategy for the treatment of TNBC.

Triple negative breast cancer (TNBC) is one kind of breast cancer that demonstrates highly aggressive tumor biology.

Interferon-gamma carrying nanoemulsion with immunomodulatory and anti-tumor activities

The therapeutic administration of cytokines has been introduced aiming to modulate the immune response system, seeking for different approaches to face pathologies such as cancer, auto immune and infectious diseases. The objective of this study was to investigate the effects of a stable oil-in-water (O/W) nanoemulsion system carrying the cytokine Interferon gamma (IFN-γ) on the activity of phagocytes and MCF-7 human breast cancer cells. Nanoemulsions were prepared through ultra-homogenization, and they consisted of distilled water, triglycerides of capric acid/caprylic, sorbitan-oleate, polysorbate 80, and 1-butanol. IFN-γ (100 ng ml^-1 ) was incorporated into two O/W nanoemulsion formulations, and these formulations were characterized in terms of their preliminary and accelerated physicochemical stability, rheological properties, droplet size, polydispersity and surface charge. We identified the most optimal IFN-γ nanoemulsion (IFN-γNE2), which remained stable under extreme temperature variations for 90 days, contained an average dose of 97 ng ml^-1 of IFN-γ and exhibited a biocompatible pH and a relative stable rheological profile. Cell viability and intracellular Ca²⁺ release assays conducted showed that IFN-γNE2 reduced the cell viability of MCF-7 cells without affecting the cell viability of phagocytes. Furthermore, IFN-γNE2 was able to induce cellular activity of phagocytes as evidenced by increased intracellular Ca²⁺ release in these cells. Our findings on this IFN-γ nanoemulsion suggest that it can be a promising therapeutic agent for immunostimulation and cancer treatment.

Design of Poly(lactic-co-glycolic Acid) (PLGA) Nanoparticles for Vaginal Co-Delivery of Griffithsin and Dapivirine and Their Synergistic Effect for HIV Prophylaxis

Long-acting topical products for pre-exposure prophylaxis (PrEP) that combine antiretrovirals (ARVs) inhibiting initial stages of infection are highly promising for prevention of HIV sexual transmission. We fabricated core-shell poly(lactide-co-glycolide) (PLGA) nanoparticles, loaded with two potent ARVs, griffithsin (GRFT) and dapivirine (DPV), having different physicochemical properties and specifically targeting the fusion and reverse transcription steps of HIV replication, as a potential long-acting microbicide product. The nanoparticles were evaluated for particle size and zeta potential, drug release, cytotoxicity, cellular uptake and in vitro bioactivity. PLGA nanoparticles, with diameter around 180–200 nm, successfully encapsulated GRFT (45% of initially added) and DPV (70%). Both drugs showed a biphasic release with initial burst phase followed by a sustained release phase. GRFT and DPV nanoparticles were non-toxic and maintained bioactivity (IC₅₀ values of 0.5 nM and 4.7 nM, respectively) in a cell-based assay. The combination of drugs in both unformulated and encapsulated in nanoparticles showed strong synergistic drug activity at 1:1 ratio of IC₅₀ values. This is the first study to co-deliver a protein (GRFT) and a hydrophobic small molecule (DPV) in PLGA nanoparticles as microbicides. Our findings demonstrate that the combination of GRFT and DPV in nanoparticles is highly potent and possess properties critical to the design of a sustained release microbicide.

Daunorubicin oral bioavailability enhancement by surface coated natural biodegradable macromolecule chitosan based polymeric nanoparticles

BACKGROUND

Daunorubicin hydrochloride (DAUN·HCl), due to low oral bioavailability poses the hindrance to be marketed as an oral formulation.

AIM OF THE STUDY

To develop a natural biodegradable macromolecule i.e. Chitosan (CS)-coated-DAUN-PLGA-poly(lactic-co-glycolic acid)-Nanoparticles (NPs) with an aim to improve oral-DAUN bioavailability and to develop as well as validate UHPLC-MS/MS (ESI/Q-TOF) method for plasma quantification and pharmacokinetic analysis (PK) of DAUN.

RESULTS

A particle size (198.3 ± 9.21 nm), drug content (47.06 ± 1.16 mg/mg) and zeta potential (11.3 ± 0.98 mV), consisting of smooth and spherical shape was observed for developed formulation. Cytotoxicity studies for CS-DAUN-PLGA-NPs revealed; a comparative superiority over free DAUN-S (i.v.) in human breast adenocarcinoma cell lines (MCF-7) and a higher permeability i.e. 3.89 folds across rat ileum, as compared to DAUN-PLGA-NPs (p < 0.01) inhuman colon adenocarcinoma cell line (Caco-2). For PK, CS-DAUN-PLGA-NPs as compared to DAUN-S, exhibited a 10.0 fold higher bioavailability in Wister rat's plasma due to presence of a natural biodegradable macromolecule i.e. CS coated on the PLGA-NPs. With regard to bioanalytical method, easy as well as a rapid method for DAUN-plasma quantification was developed as; 2.75 min and 528.49/321.54 m/z for DAUN along with 1.94 min and 544.36/397.41 m/z for IS i.e. Doxorubicin, for elution time and transition, respectively.

CONCLUSION

A novel natural biodegradable approach used in the preparation of CS coated DAUN-NPs for oral administration of DAUN is reported in this study which is can be utilized as an alternate for intravenous therapy.

Therapeutic nanoplatforms and delivery strategies for neurological disorders

The major neurological disorders found in a central nervous system (CNS), such as brain tumors, Alzheimer's diseases, Parkinson's diseases, and Huntington's disease, have led to devastating outcomes on the human public health. Of these disorders, early diagnostics remains poor, and no treatment has been successfully discovered; therefore, they become the most life-threatening medical burdens worldwide compared to other major diseases. The major obstacles for the drug discovery are the presence of a restrictive blood-brain barrier (BBB), limiting drug entry into brains and undesired neuroimmune activities caused by untargeted drugs, leading to irreversible neuronal damages. Recent advances in nanotechnology have contributed to the development of novel nanoplatforms and effective delivering strategies to improve the CNS disorder treatment while less disturbing brain systems. The nanoscale drug carriers, including liposomes, dendrimers, viral capsids, polymeric nanoparticles, silicon nanoparticles, and magnetic/metallic nanoparticles, enable the effective drug delivery penetrating across the BBB, the aforementioned challenges in the CNS. Moreover, drugs encapsulated by the nanocarriers can reach further deeper into targeting regions while preventing the degradation. In this review, we classify novel disease hallmarks incorporated with emerging nanoplatforms, describe promising approaches for improving drug delivery to the disordered CNS, and discuss their implications for clinical practice.

Poly(lactic-co-glycolic acid)(PLGA)/TiO2 nanotube bioactive composite as a novel scaffold for bone tissue engineering: In vitro and in vivo studies

The aim of this study was to synthesize and characterize novel three-dimensional porous scaffolds made of poly (lactic-co-glycolic acid)/TiO₂ nanotube (TNT) composite microspheres for bone tissue engineering applications. The incorporation of TNT greatly increases mechanical properties of PLGA/TNT microsphere-sintered scaffold. The experimental results exhibit that the PLGA/0.5 wt% TNT scaffold sintered at 100 °C for 3 h showed the best mechanical properties and a proper pore structure for tissue engineering. Biodegradation test ascertained that the weight of both PLGA and PLGA/PLGA/0.5 wt% TiO₂ nanotube composites slightly reduced during the first 4 weeks following immersion in SBF solution. Moreover, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay and alkaline phosphatase activity (ALP activity) results represent increased cell viability for PLGA/0.5%TNT composite scaffold in comparison to the control group. In vivo studies show the amount of bone formation for PLGA/TNT was approximately twice of pure PLGA. Vivid histologic images of the newly generated bone on the implants further supported our test results. Eventually, a mathematical model showed that both PLGA and PLGA/TNT scaffolds' mechanical properties follow an exponential trend with time as their degradation occurs. By a three-dimensional finite element model, a more monotonous distribution of stress was present in the scaffold due to the presence of TNT with a reduction in maximum stress on bone.

Comparative Evaluation of U.S. Brand and Generic Intravenous Sodium Ferric Gluconate Complex in Sucrose Injection: In Vitro Cellular Uptake

Iron deficiency anemia is a common clinical consequence for people who suffer from chronic kidney disease, especially those requiring dialysis. Intravenous (IV) iron therapy is a widely accepted safe and efficacious treatment for iron deficiency anemia. Numerous IV iron drugs have been approved by U.S. Food and Drug Administration (FDA), including a single generic product, sodium ferric gluconate complex in sucrose. In this study, we compared the cellular iron uptake profiles of the brand (Ferrlecit®) and generic sodium ferric gluconate (SFG) products. We used a colorimetric assay to examine the amount of iron uptake by three human macrophage cell lines. This is the first published study to provide a parallel evaluation of the cellular uptake of a brand and a generic IV iron drug in a mononuclear phagocyte system. The results showed no difference in iron uptake across all cell lines, tested doses, and time points. The matching iron uptake profiles of Ferrlecit® and its generic product support the FDA's present position detailed in the draft guidance on development of SFG complex products that bioequivalence can be based on qualitative (Q1) and quantitative (Q2) formulation sameness, similar physiochemical characterization, and pharmacokinetic bioequivalence studies.

PLGA Nanoparticles as Subconjunctival Injection for Management of Glaucoma

Nanoparticles fabricated from the biodegradable and biocompatible polymer, polylactic-co-glycolic acid (PLGA), could be a promising system for targeting ocular drug delivery. The objective of this work was to investigate the possibility of encapsulating brinzolamide in PLGA nanoparticles in order to be applied as a subconjunctival injection that could represent a starting point for developing new therapeutic strategies against increase in ocular pressure. The brinzolamide-loaded PLGA nanoparticles were fabricated using emulsion-diffusion-evaporation method with varying concentrations of Tween 80 or poloxamer 188 (Plx) in aqueous and organic phases. The nanoparticles were characterized in terms of particle size and size distribution, entrapment efficiency and in-vitro drug release pattern as well as DSC and X-ray analysis. Nanoparticles prepared using Tween 80 in the aqueous phase showed higher encapsulation efficiency and smaller particle size-values compared to those prepared using Plx. Furthermore, the addition of Plx 188 or Brij 97 to the organic phase in the formulation containing Tween 80 in the aqueous phase led to an increase in the particle diameter-values of the obtained nanoparticles. The nanoparticles had the capacity to release the brinzolamide in a biphasic release profile. The nanoparticles were spherical in shape and the drug was entraped in the nanoparticles in an amorphous form. Selected nanoparticles, injected subconjunctivally in normotensive Albino rabbits, were able to reduce the IOP for up to 10 days. Nanoparticles loaded with brinzolamide with lower particle size were able to reduce the IOP for longer period compared to those with higher particle size. Histopathological studies for the anterior cross sections of the rabbits' eyes revealed that the tested nanoparticles were compatible with the ocular tissue. The overall results support that PLGA nanoparticles, applied as subconjunctival injection, can be considered as a promising carrier for ocular brinzolamide delivery with targeting delivery of the drug to the eye tissues.

Selective laser sintering scaffold with hierarchical architecture and gradient composition for osteochondral repair in rabbits

Osteochondral defects cannot be adequately self-repaired due to the presence of the sophisticated hierarchical structure and the lack of blood supply in cartilage. Thus, one of the major challenges remaining in this field is the structural design of a biomimetic scaffold that satisfies the specific requirements for osteochondral repair. To address this hurdle, a bio-inspired multilayer osteochondral scaffold that consisted of the poly(ε-caprolactone) (PCL) and the hydroxyapatite (HA)/PCL microspheres, was constructed via selective laser sintering (SLS) technique. The SLS-derived scaffolds exhibited an excellent biocompatibility to support cell adhesion and proliferation in vitro. The repair effect was evaluated by implanting the acellular multilayer scaffolds into osteochondral defects of a rabbit model. Our findings demonstrated that the multilayer scaffolds were able to induce articular cartilage formation by accelerating the early subchondral bone regeneration, and the newly formed tissues could well integrate with the native tissues. Consequently, the current study not only achieves osteochondral repair, but also suggests a promising strategy for the fabrication of bio-inspired multilayer scaffolds with well-designed architecture and gradient composition via SLS technique.

Biodegradable nitric oxide precursor-loaded micro- and nanoparticles for the treatment of Staphylococcus aureus biofilms

Bacteria in biofilms are more difficult to eradicate than planktonic bacteria and result in treatment challenges for many chronic infectious diseases. Nitric oxide (NO) is an endogenous molecule that offers potential as an alternative to conventional antibiotics; however its sustained topical delivery to biofilms is not readily achieved. With this in mind, we report the development of biodegradable poly(lactide-co-glycolide) (PLGA) based microparticles (MP) and nanoparticles (NP) for encapsulation of the NO precursor isosorbide mononitrate (ISMN) and the controlled delivery to Staphylococcus aureus (S. aureus) biofilms. Firstly, water-in-oil-in-water (w/o/w) emulsification/solvent evaporation methods for PLGA NP and MP syntheses were experimentally optimised with respect to particle size and ISMN loading/encapsulation efficiency. The influence of various experiment parameters, such as the volume of inner aqueous phase, concentration of surfactants, mixing time on the particle size, drug loading and encapsulation efficiency were investigated systematically. Both PLGA MP and NP formulations enabled sustained ISMN release in physiological media over 3 to 5 days. PLGA MP with diameters of ∼3 μm and ISMN loading of 2.2% (w/w) were identified as the optimum delivery system and demonstrated significant antibacterial activity in S. aureus biofilms. This behaviour is considered to be due to targeted biofilm delivery through a combination of effective penetration and sustained release of ISMN.

Study of Effect of Different Factors in Formulation of Micro and Nanospheres with Solvent Evaporation Technique

Background:

There are various methods of formulation of micro and nanospheres such as solvent evaporation, solvent removal, polymerization, hot-melt encapsulation, coacervation, phase/wet inversion, spray drying, spray congealing etc. Amongst these all, solvent evaporation is one of the most widely used, researched, easy, accessible methods and for which many patents have been applied. It is thus imperative to understand the basics of effect of formulation variables and design of solvent evaporation method which will be covered in this review article.

Objective:

To discuss the various formulation factors while designing the robust micro and nanospherical systems with better morphology, entrapment and release of the drugs.

Method:

Systematic analysis of the relevant literature, bibliographies, and interactions with investigators.

Results:

From the investigation of different literatures, it was found that various factors of solvent evaporation technique may be controlled in order to design the micro and nanospheres of suitable morphology, entrapment and release characters.

Conclusion:

Various factors like type of polymer used, weight, viscosity, hydrophilicity, concentration, polymer ratio, stirring speed, emulsifier concentration, concentration of cross-linking agents, type of solvent used, rate of addition of solvent etc. Affect the yield, morphology, release and entrapment of the drug inside the system. Hence, these factors play crucial role in the design of a robust micro and nanospherical system.

Effects of borneol on the pharmacokinetics of 9-nitrocamptothecin encapsulated in PLGA nanoparticles with different size via oral administration

CONTEXT

Although nanocarriers provide promising potential for oral drug delivery, the delivery efficiency remains unsatisfactory and needs to be improved. Size is considered to be the most important characteristic of nanoparticles related to their oral absorption. Borneol has been proved to have the ability to enhance the penetration and transport of many drugs through various physical barriers.

OBJECTIVE

To investigate the effect of the particle size and coadministration of borneol on the pharmacokinetics and bioavailability of entrapped drug in different size poly(lactic-co-glycolic acid) (PLGA) nanoparticles.

MATERIALS AND METHODS

9-Nitrocamptothecin (9-NC)-loaded PLGA nanoparticles with three different range of size (50-100 nm, 100-200 nm, 200-300 nm) were prepared by emulsion solvent-evaporation method. The pharmacokinetic study in rats of these nanoparticles with borneol was carried out.

RESULTS

The experiments showed that the encapsulation drug in nanoparticles with size below 200 nm could improve the oral bioavailability of 9-NC. The small size nanoparticles (50-100 nm) had a better improvement efficacy. As for borneol, it played a significant promotion effect only on the small nanoparticles. Moreover, there was no significant influence on the nanoparticles with size more than 100 nm.

DISCUSSION AND CONCLUSION

The study indicated that both entrapping drug in nanoparticles with the size below 100 nm and coadministrating with borneol could enhance the gastrointestinal absorption of water insoluble drug. The combination of the two strategies provides a potential approach to improve the oral bioavailability of drug.

One-Step Method to Prepare PLLA Porous Microspheres in a High-Voltage Electrostatic Anti-Solvent Process

A one-step method using a high-voltage electrostatic anti-solvent process was employed to fabricate poly-l-lactide (PLLA) porous microspheres (PMs). To address the simplification and control of the preparation process, a 2⁴ full factorial experiment was performed to optimize the operating process and analyze the effect of the factors on the morphology and aerodynamic properties of the PLLA PMs, and various characterization tests were also performed. The resulting PLLA PMs exhibited an even and porous morphology with a density less than 0.4 g/cm³, a geometric mean diameter (Dg) of 10-30 μm, an aerodynamic diameter (Da) of 1-5 μm, a fine particle fraction (FPF) of 56.3%, and a porosity of 76.2%, meeting the requirements for pulmonary drug delivery. The physicochemical characterizations reveal that no significant chemical change occurred in the PLLA during the process. An investigation of its in vitro cytotoxicity and pulmonary toxicity shows no obvious toxic response, indicating good biosafety. This study indicates that the one-step method using a high-voltage electrostatic anti-solvent process has great potential in developing an inhalable drug carrier for pulmonary drug delivery.

Synthesis and characterization of tumor-targeted copolymer nanocarrier modified by transferrin

To increase the encapsulation of hydrophilic antitumor agent daunorubicin (DNR) and multidrug resistance reversal agent tetrandrine (Tet) in the drug delivery system of nano-particles (NPs), a functional copolymer NP composed of poly(lactic-co-glycolic acid) (PLGA), poly-L-lysine (PLL), and polyethylene glycol (PEG) was synthesized and then loaded with DNR and Tet simultaneously to construct DNR/Tet–PLGA–PLL–PEG-NPs using a modified double-emulsion solvent evaporation/diffusion method. And to increase the targeted antitumor effect, DNR/Tet–PLGA–PLL–PEG-NPs were further modified with transferrin (Tf) due to its specific binding to Tf receptors (TfR), which is highly expressed on the surface of tumor cells. In this study, the influence of the diversity of formulation parameters was investigated systematically, such as drug loading, mean particle size, molecular weight, the concentration of PLGA–PLL–PEG–Tf, volume ratio of acetone to dichloromethane, the concentration of polyvinyl alcohol (PVA) in the external aqueous phase, the volume ratio of the internal aqueous phase to the external aqueous phase, and the type of surfactants in the internal aqueous phase. Meanwhile, its possible effect on cell viability was evaluated. Our results showed that the regular spherical DNR/Tet–PLGA–PLL–PEG–Tf-NPs with a smooth surface, a relatively low polydispersity index, and a diameter of 213.0±12.0 nm could be produced. The encapsulation efficiency was 70.23%±1.91% for DNR and 86.5%±0.70% for Tet, the moderate drug loading was 3.63%±0.15% for DNR and 4.27%±0.13% for Tet. Notably, the accumulated release of DNR and Tet could be sustained over 1 week, and the Tf content was 2.18%±0.04%. In cell viability tests, DNR/Tet–PLGA–PLL–PEG–Tf-NPs could inhibit the proliferation of K562/ADR cells in a dose-dependent manner, and the half maximal inhibitory concentration value (total drug) of DNR/Tet–PLGA–PLL–PEG–Tf-NPs was lower than that of DNR, a mixture of DNR and Tet, and DNR/Tet–PLGA–PLL–PEG-NPs. These results clearly indicate that the PLGA–PLL–PEG formulation is a potential drug delivery system for hydrophilic and hydrophobic drugs, and that Tf modification may increase its targeting properties.

PLGA-PLL-PEG-Tf-based targeted nanoparticles drug delivery system enhance antitumor efficacy via intrinsic apoptosis pathway

Chemotherapy offers a systemic cancer treatment; however, it is limited in clinical administration due to its serious side effects. In cancer medicine, the use of nanoparticles (NPs) drug delivery system (DDS) can sustainedly release anticancer drug at the specific site and reduce the incidence of toxicity in normal tissues. In the present study, we aimed to evaluate the benefit of a novel chemotherapeutic DDS and its underlying mechanisms. Daunorubicin (DNR) was loaded into poly (lactic-co-glycolic acid) (PLGA)-poly-L-lysine (PLL)-polyethylene glycol (PEG)-transferrin (Tf) NPs to construct DNR-PLGA-PLL-PEG-Tf-NPs (DNR-loaded NPs) as a DDS. After incubating with PLGA-PLL-PEG-Tf-NPs, DNR, and DNR-loaded NPs, the leukemia K562 cells were collected and the intracellular concentration of DNR was detected by flow cytometry, respectively. Furthermore, the effect of drugs on the growth of tumors in K562 xenografts was observed and the relevant toxicity of therapeutic drugs on organs was investigated in vivo. Meanwhile, cell apoptosis in the excised xenografts was measured by transferase-mediated dUTP nick-end labeling assay, and the expression of apoptosis-related proteins, including Bcl-2, Bax, Caspase-9, Caspase-3, and cleaved-PARP, was determined by Western blotting analysis. Results showed that DNR-loaded NPs increased intracellular concentration of DNR in K562 cells in vitro and induced a remarkable improvement in anticancer activity in the xenografts in vivo. The expression of Bcl-2 protein was downregulated and that of Bax, Caspase-9, Caspase-3, and cleaved-PARP proteins were obviously upregulated in the DNR-loaded NPs group than that in other ones. Interestingly, pathological assessment showed no apparent damage to the main organs. In summary, the results obtained from this study showed that the novel NPs DDS could improve the efficacy of DNR in the treatment of leukemia and induce apoptosis via intrinsic pathway. Thus, it can be inferred that the new drug delivery may be a useful clinical tool.

Poly(sebacic anhydride) nanocapsules as carriers: effects of preparation parameters on properties and release of doxorubicin

Poly(sebacic anhydride) (PSA) is a promising polymer for the production of drug delivery vehicles. The aim of this work is to study the effect of preparation parameters on the quality of the nanoparticles. In this study, doxorubicin (DOX)-loaded PSA nanocapsules were prepared by an emulsion method. Effects of factors such as type of organic solvent, co-solute (surfactant) and its concentration on drug-loading efficiency, particle size and size distribution, morphology and release profile were examined to gain insight in the preparation and stability of nanostructures. Particles with sizes in the range of 218-1198 nm were prepared. The smallest particles with a narrow size distribution were prepared by using polyvinyl alcohol as a co-solute and dichloromethane as a solvent. Efficiency and intracellular release of doxorubicin from the formulated particles were studied on MDA-MB-231 cells. It was observed that DOX-loaded PSA particles can diffuse into the cells and intracellular antitumour activity is directly related to the released amount of drug from the PSA nanocapsules.

pH-responsive nano carriers for doxorubicin delivery

PURPOSE

The aim of this study was to design stimuli-responsive nanocarriers for anti-cancer drug delivery. For this purpose, doxorubicin (DOX)-loaded, polysebacic anhydride (PSA) based nanocapsules (NC) were combined with pH-sensitive poly (L-histidine) (PLH).

METHOD

PSA nano-carriers were first loaded with DOX and were coated with poly L-histidine to introduce pH sensitivity. The PLH-coated NCs were then covered with polyethylene glycol (PEG) to reduce macrophage uptake. The drug release profile from this system was examined in two different buffer solutions prepared as acidic (pH5) and physiological (pH 7.4) media. The physical and chemical properties of the nanocapsules were characterized by Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), ultraviolet and visible absorption spectroscopy (UV-VIS), and scanning electron microscopy (SEM). In vitro studies of the prepared nanocapsules were conducted in MDA-MB-231 breast cancer cells.

RESULTS

The results obtained by SEM and DLS revealed that nanocapsules have spherical morphology with an average size of 230 nm. Prepared pH sensitive nanocapsules exhibited pH-dependent drug release profile and promising intracellular release of drug. PEGylation of nanoparticles significantly prevented macrophage uptake compared to non-PEGylated particles.

Porous silicon oxide-PLGA composite microspheres for sustained ocular delivery of daunorubicin

A water-soluble anthracycline antibiotic drug (daunorubicin, DNR) was loaded into oxidized porous silicon (pSiO2) microparticles and then encapsulated with a layer of polymer (poly lactide-co-glycolide, PLGA) to investigate their synergistic effects in control of DNR release. Similarly fabricated PLGA-DNR microspheres without pSiO2, and pSiO2 microparticles without PLGA were used as control particles. The composite microparticles synthesized by a solid-in-oil-in-water emulsion method have mean diameters of 52.33±16.37μm for PLGA-pSiO2_21/40-DNR and the mean diameter of 49.31±8.87μm for PLGA-pSiO2_6/20-DNR. The mean size, 26.00±8μm, of PLGA-DNR was significantly smaller, compared with the other two (P<0.0001). Optical microscopy revealed that PLGA-pSiO2-DNR microspheres contained multiple pSiO2 particles. In vitro release experiments determined that control PLGA-DNR microspheres completely released DNR within 38days and control pSiO2-DNR microparticles (with no PLGA coating) released DNR within 14days, while the PLGA-pSiO2-DNR microspheres released DNR for 74days. Temporal release profiles of DNR from PLGA-pSiO2 composite particles indicated that both PLGA and pSiO2 contribute to the sustained release of the payload. The PLGA-pSiO2 composite displayed a more constant rate of DNR release than the pSiO2 control formulation, and displayed a significantly slower release of DNR than either the PLGA or pSiO2 formulations. We conclude that this system may be useful in managing unwanted ocular proliferation when formulated with antiproliferation compounds such as DNR.

Dorzolamide-loaded PLGA/vitamin E TPGS nanoparticles for glaucoma therapy: Pharmacoscintigraphy study and evaluation of extended ocular hypotensive effect in rabbits

Poor drug penetration and rapid clearance after topical instillation of a drug formulation into the eyes are the major causes for the lower ocular bioavailability from conventional eye drops. Along with this, poor encapsulation efficiency of hydrophilic drug in polymeric nanoparticles remains a major formulation challenge. Taking this perspective into consideration, dorzolamide (DZ)-loaded PLGA nanoparticles were developed employing two different emulsifiers (PVA and vitamin E TPGS) and the effects of various formulation and process variables on particle size and encapsulation efficiency were assessed. Nanoparticles emulsified with vitamin E TPGS (DZ-T-NPs) were found to possess enhanced drug encapsulation (59.8±6.1%) as compared to those developed with PVA as emulsifier (DZ-P-NPs). Transcorneal permeation study revealed a significant enhancement in permeation (1.8-2.5 fold) as compared to solution. In addition, ex vivo biodistribution study showed a higher concentration of drug in the aqueous humour (1.5-2.3 fold). Histological and IR-camera studies proved the non-irritant potential of the formulations. Pharmacoscintigraphic studies revealed the reduced corneal clearance, as well as naso-lachrymal drainage in comparison to drug solution. Furthermore, efficacy study revealed that DZ-P-NPs and DZ-T-NPs significantly reduced the intraocular pressure by 22.81% and 29.12%, respectively, after a single topical instillation into the eye.

Nanosized sustained-release pyridostigmine bromide microcapsules: process optimization and evaluation of characteristics

Background

Pyridostigmine bromide (3-[[(dimethylamino)-carbonyl]oxy]-1-methylpyridinium bromide), a reversible inhibitor of cholinesterase, is given orally in tablet form, and a treatment schedule of multiple daily doses is recommended for adult patients. Nanotechnology was used in this study to develop an alternative sustained-release delivery system for pyridostigmine, a synthetic drug with high solubility and poor oral bioavailability, hence a Class III drug according to the Biopharmaceutics Classification System. Novel nanosized pyridostigmine-poly(lactic acid) microcapsules (PPNMCs) were expected to have a longer duration of action than free pyridostigmine and previously reported sustained-release formulations of pyridostigmine.

Methods

The PPNMCs were prepared using a double emulsion-solvent evaporation method to achieve sustained-release characteristics for pyridostigmine. The preparation process for the PPNMCs was optimized by single-factor experiments. The size distribution, zeta potential, and sustained-release behavior were evaluated in different types of release medium.

Results

The optimal volume ratio of inner phase to external phase, poly(lactic acid) concentration, polyvinyl alcohol concentration, and amount of pyridostigmine were 1:10, 6%, 3% and 40 mg, respectively. The negatively charged PPNMCs had an average particle size of 937.9 nm. Compared with free pyridostigmine, PPNMCs showed an initial burst release and a subsequent very slow release in vitro. The release profiles for the PPNMCs in four different types of dissolution medium were fitted to the Ritger-Peppas and Weibull models. The similarity between pairs of dissolution profiles for the PPNMCs in different types of medium was statistically significant, and the difference between the release curves for PPNMCs and free pyridostigmine was also statistically significant.

Conclusion

PPNMCs prepared by the optimized protocol described here were in the nanometer range and had good uniformity, with significantly slower pyridostigmine release than from free pyridostigmine. This novel sustained-release delivery nanosystem for pyridostigmine might alleviate the need to identify new acetylcholinesterase inhibitors.

Surface-modified solid lipid nanoparticulate formulation for ifosfamide: development and characterization

Aims: The present research focuses on the development of the surface modified solid lipid nanoparticulate (SLN) system for enhancing the stability and sustaining the release of a model hydrophilic drug ifosfamide. Materials & Methods: SLNs consisting of glyceryl monooleate (GMO) and chitosan were prepared by double emulsion technique, crosslinked with sodium tripolyphosphate, followed by lyophilization under two different vacuum conditions. The physicochemical characterization of SLNs included evaluation of surface morphology, particle size and surface charge, moisture content and physical state of the drug in the delivery system. The in vitro drug release and the stability were evaluated using high-performance liquid chromatography and liquid chromatography/mass spectrometry, respectively. Cellular permeability and subcellular localization studies were performed using Caco-2 cells. Results: Different chamber pressures during lyophilization produced SLNs with different morphologies and moisture contents. SLNs demonstrated high encapsulation efficiency, sustained release, and enhanced stability of ifosfamide with a high cellular uptake and permeability for Caco-2 cells. Conclusion: GMO and chitosan SLNs could be successfully used for enhancing the stability, sustaining the release, enhancing the targeting and permeability characteristics of ifosfamide.

Preparation and in vitro evaluation of poly(D,L-lactide-co-glycolide) air-filled nanocapsules as a contrast agent for ultrasound imaging

The aim of this study was to prepare air-filled nanocapsules intended ultrasound contrast agents (UCAs) with a biodegradable polymeric shell composed of poly(d,l-lactide-co-glycolide) (PLGA). Because of their size, current commercial UCAs are not capable of penetrating the irregular vasculature that feeds growing tumors. The new generation of UCAs should be designed on the nanoscale to enhance tumor detection, in addition, the polymeric shell in contrast with monomolecular stabilized UCAs improves the mechanical properties against ultrasound pressure and lack of stability. The preparation method of air-filled nanocapsules was based on a modification of the double-emulsion solvent evaporation technique. Air-filled nanocapsules with a mean diameter of 370±96nm were obtained. Electronic microscopies revealed spherical-shaped particles with smooth surfaces and a capsular morphology, with a shell thickness of ∼50nm. Air-filled nanocapsules showed echogenic power in vitro, providing an enhancement of up to 15dB at a concentration of 0.045mg/mL at a frequency of 10MHz. Loss of signal for air-filled nanocapsules was 2dB after 30min, suggesting high stability. The prepared contrast agent in this work has the potential to be used in ultrasound imaging.

Biomedical Applications of Biodegradable Polymers

Utilization of polymers as biomaterials has greatly impacted the advancement of modern medicine. Specifically, polymeric biomaterials that are biodegradable provide the significant advantage of being able to be broken down and removed after they have served their function. Applications are wide ranging with degradable polymers being used clinically as surgical sutures and implants. In order to fit functional demand, materials with desired physical, chemical, biological, biomechanical and degradation properties must be selected. Fortunately, a wide range of natural and synthetic degradable polymers has been investigated for biomedical applications with novel materials constantly being developed to meet new challenges. This review summarizes the most recent advances in the field over the past 4 years, specifically highlighting new and interesting discoveries in tissue engineering and drug delivery applications.