PLGA Encapsulation Research Articles

Development of an Injectable DNA Vaccine Against Aeromonas hydrophila Infection Nanoencapsulated With Poly(Lactic‐Co‐Glycolic) Acid (PLGA) in Common Carp

In this study, we developed an injectable DNA vaccine targeting the aopB gene of Aeromonas hydrophila, encapsulated within poly(lactic‐co‐glycolic acid) (PLGA) nanoparticles, for use in common carp. Juvenile common carp were divided into six groups with three replicates each. Groups A and B received intramuscular injections of the plasmid containing the target gene (pCDNA3.1‐aopB) with or without encapsulation, respectively. Groups C and D received the plasmid lacking the target gene via the same route. Group E received PLGA, while Group F (control) received phosphate‐buffered saline. Sampling occurred on days 0, 30, and 60, and hematological and immunological indices were compared among the groups. On day 60, all groups were challenged with Aeromonas hydrophila, and cumulative mortality rates were assessed. Our results indicated successful detection of the target gene in various tissues of vaccinated fish. Notably, vaccinated groups exhibited a significant decrease in cumulative mortality (p < 0.05). Immunological indices, such as serum antibody titer and nonspecific immune responses, significantly improved in vaccinated groups, particularly those receiving the DNA vaccine with PLGA encapsulation (p < 0.05). Overall, the DNA vaccine, especially when nanoencapsulated with PLGA, demonstrated efficacy and immunogenicity against A. Hydrophila in common carp, suggesting its potential as a vaccination strategy against this infection. Further research could optimize its effectiveness and applicability.

Anti-Pyretic, Analgesic, and Anti-Inflammatory Activities of Meloxicam and Curcumin Co-Encapsulated PLGA Nanoparticles in Acute Experimental Models.

Herein, we evaluated the in vivo effects of meloxicam and curcumin co-encapsulated PLGA nanoparticles in experimental acute models of pyrexia, nociception, and inflammation. Seven groups (n = 6) were designed for each investigation and pretreated intraperitoneally (i.p.): the control group, meloxicam (4 mg/kg b.w.), curcumin (15 mg/kg b.w.), and equivalent content containing PLGA capped nanoparticles of meloxicam (Mlx-NP) and curcumin (Cur-NP) alone and in combination (Mlx-Cur-NP; at two doses). The results showed that PLGA encapsulation significantly (p ≤ 0.05) improved the in vivo activities of each compound. Furthermore, co-encapsulation of meloxicam and curcumin potentiated the anti-pyretic effect on yeast-induced pyretic rats, anti-nociceptive effect on nociception induced in rats by formalin and heat, and anti-edematogenic activity in xylene-induced ear edema in rats in a dose-dependent manner. In carrageenan-induced paw inflammation in rats, meloxicam and curcumin co-loading (Mlx-Cur-NP) resulted in significant (p ≤ 0.05) inhibition of paw inflammation, reduction in TNF-α and PGE2 levels, downregulation of expressions of pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6), as well as a decrease in histopathological changes and TNF-α immunoexpression in paw tissues. Moreover, Mlx-Cur-NP demonstrated noteworthy potentiation in pharmacological effects compared to free compounds and mono-compound-loaded nanoparticles. Thus, the association of meloxicam with curcumin in a biodegradable nanocarrier system could provide a promising anti-pyretic, anti-nociceptive, and anti-inflammatory therapeutic approach for acute conditions.

The potency of PLGA-Encapsulated Epigallocatechin Gallate (EGCG) as adjuvant therapy for chronic kidney disease

Chronic kidney disease (CKD) prevalence keeps increasing worldwide and being particular concern due to its morbidity and mortality. However, current CKD therapy are known to be economically costly and not necessarily provide better outcomes. Epigallocatechin gallate (EGCG) is one of the substances that widely studied as perspective therapeutic agents of CKD due to its anti-inflammatory, antioxidant, and enhancing mitochondrial function ability. However, the use of EGCG is limited to low bioavailability and poor pharmacokinetic profile. Encapsulation of EGCG with PLGA is expected to increase the efficacy of EGCG especially for its use as the kidney protective agent and optimize therapy of CKD. Thus, this study aims to analyze the potency of PLGA-encapsulated EGCG as the adjuvant therapy for CKD. This study was a narrative review summarizes studies related to current adjuvant therapy of CKD. EGCG has beneficial effects in reducing pro-inflammatory cytokines among chronic kidney disease. EGCG also can increase scavenging of free radicals to decrease reactive oxygen species. EGCG is known to enhance mitochondrial function and increase mitochondrial protection to prevent apoptosis in various kidney diseases. Combination of PLGA encapsulation with EGCG has a beneficial effect in improving the delivery, bioavailability, stability, and the pharmacokinetic profile of EGCG. PLGA-encapsulated EGCG also provides a better therapeutic effect on preventing and decreasing progression of kidney damage. Finally, this study concluded that combination of PLGA-encapsulated EGCG has a potency as the adjuvant therapy of CKD.

Combined Application of Prototype Ultrasound and BSA-Loaded PLGA Particles for Protein Delivery.

To develop an in vitro culture system for tissue engineering to mimic the in vivo environment and evaluate the applicability of ultrasound and PLGA particle system. For tissue engineering, large molecules such as growth factors for cell differentiation should be supplied in a controlled manner into the culture system, and the in vivo microenvironment need to be reproduced in the system for the regulation of cellular function. In this study, portable prototype ultrasound with low intensity was devised and tested for protein release from bovine serum albumin (BSA)-loaded poly(lactic-co-glycolic acid) (PLGA) particles. BSA-loaded PLGA particles were prepared using various types of PLGA reagents and their physicochemical properties were characterized including particle size, shape, or aqueous wetting profiles. The BSA-loaded formulation showed nano-ranged size distribution with optimal physical stability during storage period, and protein release behaviors in a controlled manner. Notably, the application of prototype ultrasound with low intensity influenced protein release patterns in the culture system containing the BSA-loaded PLGA formulation. The results revealed that the portable ultrasound set controlled by the computer could contribute for the protein delivery in the culture medium. This study suggests that combined application with ultrasound and protein-loaded PLGA encapsulation system could be utilized to improve culture system for tissue engineering or cell regeneration therapy.

Targeted Delivery of Curcumin Rescues Endoplasmic Reticulum-Retained Mutant NOX2 Protein and Avoids Leukocyte Apoptosis.

Chronic granulomatous disease (CGD) is a primary immunodeficiency disease caused by defects in the leukocyte NADP oxidase. We previously reported that sarcoplasmic/endoplasmic reticulum calcium pump (SERCA) inhibitors could be used to rescue mutant H338Y-gp91phox protein of a particular type of CGD with a CybbC1024T mutation, leading to endoplasmic reticulum (ER) retention of the mutant protein. In this study, we developed a novel mouse model with the CybbC1024T mutation on a Cybb knockout background and investigated the therapeutic effects of ER-targeted delivery of the SERCA inhibitor, curcumin, with poly(lactic-coglycolic acid) (PLGA) nanoparticles (NPs). We found that PLGA encapsulation improved the efficacy of curcumin as a SERCA inhibitor to induce ER calcium release. ER-targeting curcumin-loaded PLGA NPs reduced and delayed extracellular calcium entry and protected the cells from mitochondrial damage and apoptosis. In vivo studies showed that ER-targeting curcumin-loaded PLGA NPs treatment enhanced neutrophil gp91phox expression, ROS production and peritoneal bacterial clearance ability of the CybbC1024T transgenic Cybb -/- mice. Our findings indicate that ER-targeted delivery of curcumin not only rescues ER-retained H338Y-gp91phox protein, and hence leukocyte function, but also enhances the bioavailability and reduces cytotoxicity. Modulation of ER function by using organelle-targeted NPs may be a promising strategy to improve the therapeutic potential of curcumin as a treatment for CGD.

Effect of nanoencapsulation using poly (lactide-co-glycolide) (PLGA) on anti-angiogenic activity of bevacizumab for ocular angiogenesis therapy

Antibody-based therapy is an effective strategy for treating ocular angiogenesis. However, short-acting efficacy and poor treatment compliance usually occurs in clinical practices. Thus, it is required to develop a drug delivery system to improve the bioavailability and decrease the toxicity of anti-angiogenic antibody. Bevacizumab is a recombinant humanized monoclonal antibody against vascular endothelial growth factor (VEGF). In this study, bevacizumab was encapsulated into poly (lactide-co-glycolide) (PLGA) nanoparticles. PLGA encapsulation could prolong the residency of bevacizumab in the vitreous and aqueous humor and produce long-lasting drug concentrations. Bevacizumab-encapsulated PLGA had no significant cytotoxicity and tissue toxicity effect in vitro and in vivo. In vitro studies showed that bevacizumab-encapsulated PLGA was more effective than bevacizumab in inhibiting VEGF-mediated endothelial cell proliferation, migration and tube formation. In vivo studies showed that bevacizumab-encapsulated PLGA enhanced the anti-angiogenic efficiency of bevacizumab for treating corneal neovascularization and retinal neovascularization. Thus, bevacizumab-encapsulated PLGA could increase the bioavailability and decrease the toxicity of bevacizumab during ocular angiogenesis therapy.

Abstract 1975: Disulfiram targets hypoxia-induced cancer stem cells and reverses chemoresistance in non-small cell lung cancer

Abstract Background: This study aims to repurpose disulfiram (DS), a drug used to treat alcohol dependence, into an effective treatment for non-small cell lung cancer (NSCLC). NSCLC is the leading cause of cancer related death worldwide because of early metastasis and chemoresistance. Cancer stem cells (CSCs) play a key role in resistance and metastasis. Our previous studies indicate that tumor hypoxia induced activation of the nuclear factor-κB (NF-κB) pathway, a pivotal regulator of CSCs. Therefore, development of an NF-κB and CSCs targeting drug will improve NSCLC therapeutic outcomes. New drug development is an expensive and time-consuming procedure. Cytotoxicity of DS is copper (II) (Cu)-dependent. DS/Cu induces reactive oxygen species, inhibits NF-κB activity and demonstrates excellent in vitro anti-CSCs activity in a wide range of cancers. The clinical application of DS as an anticancer drug is impeded by its very short half-life in the bloodstream. To improve the drug delivery efficiency, we developed a poly lactic-co-glycolic-DS (PLGA-DS), which demonstrates strong anti-cancer efficacy in mouse NSCLC models. Methods: NSCLC cell line A549 and H23 cultured as spheroids, hypoxia and PCDNA-3.1 NF-κB p65 transfect A659 cell lines. The cytotoxic effect of DS/Cu analyzed using sphere reformation, clonogenic and MTT assays. Flow cytometric analysis to detect CSC markers ALDH and CD44, and analysis of apoptosis by Annexin V. Western blot analysis to determine expression of embryonic stem cell markers Nanog and OCT4, and identify the importance of the NF-κB pathway together with HIF and including expression of associated apoptotic proteins Bax and Bcl2. Results: CSC and hypoxic cultured cells expressed high levels of CSC markers and were resistant to first and second line NSCLC anticancer drugs (doxorubicin, oxaliplatin, paclitaxel and gemcitabine). High NF-κB expression was detected in CSCs and hypoxia-cultured NSCLC cell lines. After transfection with p65 subunit of NF-κB, A549 cells expressed CSC markers and became resistant to a wide range of anticancer drugs. DS (5-10 nM) supplemented with Cu (10 μM) induced cytotoxicity to hypoxic cultured NSCLC cells, DS (1 μM) in combination with Cu inhibited sphere reformation. DS/Cu effectively inhibited NF-κB activity, abolished the CSC population and synergistically enhanced the cytotoxicity of the above conventional anticancer drugs. Our study also shows that PLGA-DS extends the half-life of free DS in the blood stream from 30 seconds to 7 hours. Intravenous injection of PLG-DS in combination with oral Cu can effectively inhibit the growth of subcutaneous and lung NSCLC xenografts. Conclusion: DS/Cu specifically inhibits NF-κB pathway and targets CSC in NSCLC cell lines. PLGA encapsulation improves delivery of DS which demonstrated very strong anticancer activity in NSCLC xenografts in vivo. Citation Format: Kate Butcher, Vinodh Kannappan, Karim Azar, Rajagopal Kilari, Ogechi Nkeonye, Mark R. Morris, Christopher McConville, Yaohe Wang, Weiguang Wang. Disulfiram targets hypoxia-induced cancer stem cells and reverses chemoresistance in non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1975.

PLGA encapsulation and radioiodination of indole-3-carbinol: investigation of anticancerogenic effects against MCF7, Caco2 and PC3 cells by in vitro assays

Encapsulation with PLGA of I3C and radioiodination have been performed. Anticancerogenic effects of I3C and I3C-PLGA have been investigated utilizing in vitro methods on breast adenocarcinoma epithelial (MCF7), colon adenocarcinoma epithelial (Caco2), prostate carcinoma epithelial (PC3) cells. Characterization of I3C-PLGA have been performed with DLS method and SEM analysis. I3C and I3C-PLGA compounds have been radiolabeled in high yields with 131I which is widely used for diagnosis and treatment in Nuclear Medicine. All experimental results demonstrated that radioiodinated compounds are promising in order to be used in Nuclear Medicine as well as present study contributed previously reported studies.

Characterization of Immune Responses to an Inactivated Avian Influenza Virus Vaccine Adjuvanted with Nanoparticles Containing CpG ODN.

Avian influenza virus (AIV), a mucosal pathogen, gains entry into host chickens through respiratory and gastrointestinal routes. Most commercial AIV vaccines for poultry consist of inactivated, whole virus with adjuvant, delivered by parenteral administration. Recent advances in vaccine development have led to the application of nanoparticle emulsion delivery systems, such as poly (d,l-lactic-co-glycolic acid) (PLGA) nanoparticles to enhance antigen-specific immune responses. In chickens, the Toll-like receptor 21 ligand, CpG oligodeoxynucleotides (ODNs), have been demonstrated to be immunostimulatory. The objective of this study was to compare the adjuvant potential of CpG ODN 2007 encapsulated in PLGA nanoparticles with nonencapsulated CpG ODN 2007 when combined with a formalin-inactivated H9N2 virus, through intramuscular and aerosol delivery routes. Chickens were vaccinated at days 7 and 21 posthatch for the intramuscular route and at days 7, 21, and 35 for the aerosol route. Antibody-mediated responses were evaluated weekly in sera and lacrimal secretions in specific pathogen-free chickens. The results indicate that nonencapsulated CpG ODN 2007 in inactivated AIV vaccines administered by the intramuscular route generated higher antibody responses compared to the encapsulated CpG ODN 2007 formulation by the same route. Additionally, encapsulated CpG ODN 2007 in AIV vaccines administered by the aerosol route elicited higher mucosal responses compared to nonencapsulated CpG ODN 2007. Future studies may be aimed at evaluating protective immune responses induced with PLGA encapsulation of AIV and adjuvants.

PLGA encapsulation effect on Bioquin-HMPAO: radiolabeling and in vitro behaviour on brain and lung cancer cells

Bioquin-HMPAO (BH) was previously investigated as a novel brain imaging agent by in vivo biodistribution studies. Present studies are carried out to explore radiolabeling and in vitro behaviour evaluation of poly (lactic-co-glycolic acid) (PLGA) encapsulated BH nanocapsules (BH-PLGA NCs). BH-PLGA NCs were characterized utilizing dynamic light scattering and scanning electron microscope. Encapsulation effect on radiolabeling with 99mTc was examined by stability and lipophilicity studies and effect on in vitro behaviour of 99mTc-BH was evaluated by incorporation studies on DAOY, U87-MG and A549 cells. It is observed that PLGA encapsulation has a positive and reinforcement effect.

Biocompatible PLGA-oil hybrid nanoparticles for high loading and controlled delivery of resveratrol

The art of hybridization has recently emerged as promising strategy to alleviate the limitations associated with PLGA nanoparticles (NPs). The present study reports the development of a hybrid nanosystem by integrating the mechanical advantages of PLGA and high drug encapsulation property of oil into a single system. This hybrid system exhibited core-shell architecture where the oil formed core while PLGA created the outer shell. Several critical factors affecting the formulation of polymer-oil nanohybrids (PONHs) were optimized. The narrow sized (144 nm) PONHs showed remarkable loading capacity (29.2% w/w) and, also showed an improvement in control release capability, antioxidant activity and stability as compared to standard PLGA NPs. Core-shell nature of the PONHs was found a key factor responsible for the improved efficacy. The developed formulations exhibited excellent biocompatibility with normal monkey kidney (Vero) cell lines. The promising results support that PONHs would be a next generation drug delivery system and their strong clinical impact in near future is anticipated.

99mTc labeled plumbagin: estrogen receptor dependent examination against breast cancer cells and comparison with PLGA encapsulated form

Plant origin products having anticancer properties come into prominence due to widespread of cancer. Plumbagin has various biological activities like anticancer activity. Estrogen receptor (ER) specificity of plumbagin (PL) and radiolabeled PL investigated by in vitro studies on ER+ and ER− adenocarcinoma cells. Additionally, PLGA encapsulation was carried out to reduce toxicity of plumbagin and encapsulation effect was investigated. Plumbagin radiolabeled with 100 % in yields and had ER specificity. Furthermore, PLGA encapsulation effected positively on properties of plumbagin; reduced toxicity, increased stability and ER specificity. A promising agent for the diagnosis of ER+ breast cancer is suggested.

Abstract 581: Surfactant-free PLGA encapsulation facilitates delivery of LY294002 to endoplasmic reticulum and enhances its cytotoxicity.

Abstract LY294002 (LY) is a potent inhibitor of phosphatidylinositol 3-kinases (PI3Ks); however, bio-applications of LY are limited by its poor solubility and pharmacokinetic profile. Poly(lactic-co-glycolic acid) (PLGA) is a biodegradable nanomaterial that can be used as a carrier for drug delivery. Although LY-loaded polyvinyl alcohol (PVA)-containing PLGA nanoparticles (PVA-LY NPs) have been developed to improve LY solubility, the ratio of NP internalization is unsatisfactory and the cytotoxicity of PVA-LY NPs is inferior to that of free LY. LY-loaded surfactant-free PLGA nanoparticles (SF-LY NPs) were developed to improve the therapeutic efficacy of LY. The size of SF-LY NPs was in the range of 80-100 nm, the shape was spherical and the NPs were monodispersed. The loading capacity of LY in SF NPs was 7.4μg/mg with a sustained-released pattern. In four lung cancer cell lines, SF-LY NPs showed a stronger growth inhibitory effect, sustained suppression of the serine/threonine kinase AKT activation, and increased intracellular uptake of LY compared with PVA-LY NPs or free LY. In addition, it was observed that SF NPs tend to accumulate in the endoplasmic reticulum (ER) and subsequently induce pronounced ER stress. After injection into tumors, SF-LY NPs exhibited a stronger antitumor effect than free LY. These findings indicated that the surfactant-free formulation of PLGA is an ideal vector to carry LY and that SF-LY NPs possess promising anticancer activity. Citation Format: Chia-Cheng Hou. Surfactant-free PLGA encapsulation facilitates delivery of LY294002 to endoplasmic reticulum and enhances its cytotoxicity. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 581. doi:10.1158/1538-7445.AM2013-581

Antimicrobial Efficacy of Poly (DL‐lactide‐co‐glycolide) (PLGA) Nanoparticles with Entrapped Cinnamon Bark Extract against Listeria monocytogenes and Salmonella typhimurium

Nanoencapsulation of active compounds using poly-(d,l-lactide-co-glycolide) (PLGA) is commonly used in the pharmaceutical industry for drug delivery and may have important applications in the food industry. Control of growth of foodborne bacteria with the goals of reducing the number of foodborne illness outbreaks, assuring consumers a safer food supply remains a priority in the food industry. Natural antimicrobials are an excellent way to eliminate pathogens without introducing chemical preservatives that consumers may find undesirable. Cinnamon bark extract (CBE) is an effective pathogen inhibitor isolated from cinnamon spice. PLGA nanoparticles containing CBE were produced using an emulsion-solvent evaporation method and characterized for size, polydispersity, morphology, entrapment efficiency, in vitro release and pathogen inhibition. PLGA with 2 different ratios of lactide to glycolide (65:35 and 50:50) were used to determine how polymer composition affected nanoparticle characteristics and antimicrobial potency. The size of the nanoparticles ranged from 144.77 to 166.65 nm and the entrapment efficiencies of CBE in 65:35 PLGA and 50:50 PLGA were 38.90% and 47.60%, respectively. The in vitro release profile at 35 °C showed an initial burst effect for both types of PLGA followed by a more gradual release of CBE from the polymer matrix. Both types of PLGA nanoparticles loaded with CBE were effective inhibitors of Salmonella enterica serovar Typhimurium and Listeria monocytogenes after 24 and 72 h at concentrations ranging from 224.42 to 549.23 μg/mL. The PLGA encapsulation improved delivery of hydrophobic antimicrobial to the pathogens in aqueous media.

Intracellular Drug Release from Curcumin-Loaded PLGA Nanoparticles Induces G2/M Block in Breast Cancer Cells

PLGA nanoparticles are among the most studied polymer nanoformulations for several drugs against different kinds of malignant diseases, thanks to their in vivo stability and tumor localization exploiting the well-documented "enhanced permeation and retention" (EPR) effect. In this paper, we have developed uniform curcumin-bearing PLGA nanoparticles by a single-emulsion process, which exhibited a curcumin release following a Fickian-law diffusion over 10 days in vitro. PLGA nanoparticles were about 120 nm in size, as determined by dynamic light scattering, with a surface negative charge of -30 mV. The loading ratio of encapsulated drug in our PLGA nanoformulation was 8 wt%. PLGA encapsulation provided efficient protection of curcumin from environment, as determined by fluorescence emission experiments. Next, we have investigated the possibility to study the intracellular degradation of nanoparticles associated with a specific G2/M blocking effect on MCF7 breast cancer cells caused by curcumin release in the cytoplasm, which provided direct evidence on the mechanism of action of our nanocomplex. This study was carried out using Annexin V-based cell death analysis, MTT assessment of proliferation, flow cytometry, and confocal laser scanning microscopy. PLGA nanoparticles proved to be completely safe, suggesting a potential utilization of this nanocomplex to improve the intrinsically poor bioavailability of curcumin for the treatment of severe malignant breast cancer.

Prolonged Antibiotic Release by PLGA Encapsulation on Titanium Alloy

Deep infection after artificial joint arthroplasty is a devastating complication. Local antibiotic delivery in revision surgery is useful in preventing the recurrence of infection. The present study investigates whether encapsulated antibiotic-loaded plasma-sprayed titanium alloy hip prosthesis materials that use biodegradable poly (lactic-co-glycolic acid) (PLGA) copolymer extend the duration of steady antibiotic release without a burst release. Two kinds of antibiotic (vancomycin and cefuroxime) and various concentrations and number of layers of PLGA encapsulation are investigated to determine the optimal antibiotic release. The antibiotic release is quantified with an elution test. The extracts were collected at 1, 6, and 12 hours and daily after 24 hours for antibiotic concentration analysis using a spectrophotometer. The degradation of PLGA correlated with the antibiotic release rate is characterized by weight change, pH value, and morphology observation. The effective antibiotic release durations for single-layer 15% PLGA in the vancomycin group, single-layer 15% PLGA in the cefuroxime group, double-layer 15% PLGA in the cefuroxime group, and one layer of 30% PLGA over one layer of 15% PLGA are 5, 7, 10, and 17 days, respectively. PLGA encapsulation can provide an extended antibiotic release of up to 2.5 weeks without a burst release. The release can be further extended in vivo to reach clinical effectiveness.

Fabrication of novel niclosamide-suspension using an electrospray system to improve its therapeutic effects in ovarian cancer cells in vitro

This work describes the feasibility of using a single- or dual-capillary electrospray (ES) system to produce a series of novel niclosamide suspensions. Analytical results indicate that the ES system generates a homogeneous suspension of pure niclosamide or niclosamide-encapsulated poly(D,L-lactic-co-glycolide) (PLGA) particles in phosphate buffer saline (PBS). Also, the suspension solution remains stable for several months. SEM images reveal that the pure niclosamide particles all have a rod-like shape (transversal length: 105±21nm, longitudinal length: 493±151nm) and the niclosamide-encapsulated PLGA particles are spherical with a diameter of approximately 584–662nm. Additionally, qualitative and quantitative analyses are performed using UV–vis spectroscopy, which yields two characteristic absorption peaks that are attributed to niclosamide (336nm and 376nm, in PBS medium). Based on use of this information as an index, a standard curve is established for quantification. Raman spectra analysis indicates that the generated pure niclosamide or niclosamide-encapsulated PLGA particles are all composed of niclosamide monohydrate instead of an anhydrous form of niclosamide. According to in vitro cell studies, this novel suspension of niclosamide with or without PLGA encapsulation exhibits a better anti-proliferative ability against CP70 and SKOV-3 ovarian cancer cells than that of conventional formulation. In particular, the anti-proliferative ability of niclosamide-encapsulated PLGA particles against CP70 cells is better than that of pure niclosamide suspension, which is likely caused by the more efficient intracellular delivery.

Therapeutic effect of chitosan modification on salmon-calcitonin-loaded PLGA nanoparticles

Although salmon-calcitonin (sCT) has been known as a potent drug for the treatment of osteoporosis, its oral dosage form products have not been commercially available primarily due to a poor oral bioavailability. Chitosan has been extensively examined as a potential oral absorption enhancer, whereas encapsulation with PLGA has been widely studied to address the delivery problems of typical peptide drug molecules. We investigated the mechanism and therapeutic effect of chitosan modification on the sCT-loaded PLGA nanoparticles. Chitosan was added onto these particles in two ways: by incorporation during W/O/W emulsification and by solid dipping. Particles were characterized by particle size analyzer, Zeta potential analyzer, scanning electron microscopy, and so forth. Nano-sized particles of 430–590 nm in fairly spherical shape with a narrow size distribution were produced. The PLGA encapsulation efficiency greater than 50% of added sCT was achieved regardless of chitosan modification. It turned out that sCT-loaded PLGA particles with chitosan modified during W/O/W emulsification (referred to as sCT-PLGA-CHT1) showed better therapeutic behavior in terms of sustained release effects as well as short-period hypocalcemic effects than the others. It was concluded that the beneficial effect was greatly associated with the formation of embedded structure of chitosan molecules when particles were modified with chitosan.

PLGA and PHBV Microsphere Formulations and Solid-State Characterization: Possible Implications for Local Delivery of Fusidic Acid for the Treatment and Prevention of Orthopaedic Infections

To develop and characterize the solid-state properties of poly(DL-lactic-co-glycolic acid) (PLGA) and poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid) (PHBV) microspheres for the localized and controlled release of fusidic acid (FA). The effects of FA loading and polymer composition on the mean diameter, encapsulation efficiency and FA released from the microspheres were determined. The solid-state and phase separation properties of the microspheres were characterized using DSC, XRPD, Raman spectroscopy, SEM, laser confocal and real time recording of single microspheres formation. Above a loading of 1% (w/w) FA phase separated from PLGA polymer and formed distinct spherical FA-rich amorphous microdomains throughout the PLGA microsphere. For FA-loaded PLGA microspheres, encapsulation efficiency and cumulative release increased with initial drug loading. Similarly, cumulative release from FA-loaded PHBV microspheres was increased by FA loading. After the initial burst release, FA was released from PLGA microspheres much slower compared to PHBV microspheres. A unique phase separation phenomenon of FA in PLGA but not in PHBV polymers was observed, driven by coalescence of liquid microdroplets of a DCM-FA-rich phase in the forming microsphere.

Preparation and characterization of PE38KDEL-loaded anti-HER2 nanoparticles for targeted cancer therapy

The clinical use of immunotoxins is severely limited by nonspecific toxicity. To overcome this limitation, PE38KDEL was used as a model protein toxin to prepare PE38KDEL-loaded poly(lactic-co-glycolic acid) (PLGA) antibody modified nanoparticles (NPs), which were covalently conjugated with Fab' fragments of a humanized anti-HER2 monoclonal antibody (rhuMAbHER2) by a two-step carbodiimide method. The characterization of the PE38KDEL-loaded nanoparticles-anti-Fab' bioconjugates (PE-NPs-HER), such as particle size, zeta potential and morphology, were evaluated by dynamic light-scattering detector and transmission electron microscope (TEM). Micro BCA assay was used to determine the drug encapsulation efficiency and the quantity of Fab' conjugated with NPs. The binding affinity and internalization efficiency of PE-NPs-HER were demonstrated by flow cytometry and laser-scanning confocal microscopy. In comparison with PE38KDEL-loaded nanoparticles (PE-NPs) that lack anti-HER2 Fab', PE-NPs-HER had superior in vitro cytotoxicity against HER2-overexpressing breast cancer cell lines. Progressively, PE-NPs-HER has superior protective antitumor activity in HER2-overexpressing tumor-bearing mice than the control immunotoxin PE-HER constructed by chemically coupling PE38KDEL to rhuMAbHER2. Most strikingly, in developed HER2-overexpressing tumor xenograft model, administration of PE-NPs-HER (0.9 mg/kg) showed a much better therapeutic efficacy in inhibiting tumor growth compared with PE-HER and other controls: final mean tumor load was 13 ± 6 mm 3 (mean ± SD; n = 8, significantly smaller than all other groups by ANOVA at 95% confidence interval). In addition, PE-NPs-HER were well tolerated in mice with a much higher MTD (maximally tolerated dose) than PE-HER (2.92 mg/kg vs. 0.92 mg/kg), indicating the systemic toxicity of PE38KDEL was dramatically reduced by PLGA encapsulation. Thus, the bioconjugates PE-NPs-HER may represent a potentially useful strategy for cancer therapy.