Enzyme Responsive Delivery of Anti-Retroviral Peptide via Smart Hydrogel.

In response to an urgent need for advanced formulations for the delivery of anti-retrovirals, a stimuli-sensitive hydrogel formulation that intravaginally delivers HIV-1 entry inhibitor upon being exposed to a specific protease was developed. The hydrogel formulation consists of PEG-azide and PEG-DBCO covalently linked to the entry inhibitor peptide, enfuvirtide, via substrate linker that is designed to undergo proteolysis by prostate specific antigen (PSA) present in seminal fluid and release innate enfuvirtide. Of the tested PSA substrate linkers (HSSKLQYY, GISSFYSSK, AYLMYY, and AYLMGRR), HSSKLQ was found to be an optimal candidate for PEG-based hydrogel with kcat/KM of 2.2 M-1 s-1. The PEG-based hydrogel displayed a pseudoplastic, thixotropic behavior with overall viscosity varying between 1516 and 2.2 Pa.s, within the biologically relevant shear rates of 0.01-100 s-1. It also exhibited viscoelastic properties appropriate for uniform spreading and being retained in vagina. PEG-based hydrogels were loaded with N3-HSSKLQ-enfuvirtide (HF42) that is customarily synthesized enfuvirtide prodrug with its N-terminus connected to HSSKLQ linker. The stimuli-sensitive PEG-based hydrogel formulations upon being exposed to PSA released 36.5 ± 4.8% of enfuvirtide over 24 h in human ejaculate mimic of vaginal simulant fluid and seminal simulant fluid mixed in 1:3 ratio, which is significantly greater than its IC50. The PEG-based hydrogel was non-cytotoxic to both vaginal epithelial cells (VK2/E6E7) and murine macrophages (RAW 264.7) and did not significantly induce the production of nitric oxide, an inflammatory mediator. The PEG-based hydrogel is found to have suitable physicochemical properties for an intravaginal formulation of the PSA substrate-linked anti-retrovirals and is safe towards vaginal epithelium. It is capable of delivering enfuvirtide with effective concentrations to prevent women from HIV-1 infection.

Parametric Optimization of 3D Printed Hydrogel-Based Cardiovascular Stent.

PURPOSE: This study aimed to develop personalized biodegradable stent (BDS) for the treatment of coronary heart disease. Three-dimensional (3D) printing technique has offered easy and fast fabrication of BDS with enhanced reproducibility and efficacy. METHODS: A variety of BDS were printed with 3 types of hydrogel (~5 ml) resources (10%w/v sodium alginate (SA), 10%w/v cysteine-sodium alginate (SA-CYS), and 10%w/v cysteine-sodium alginate with 0.4%w/v PLA-nanofibers (SA-CYS-NF)) dispersed from an 22G print head nozzle attached to the BD-syringe. The printability of hydrogels into 3D structures was examined based on such variables as hydrogel's viscosity, printing distance, printing speed and the nozzle size. RESULTS: It was demonstrated that alginate composition (10%w/v) offered BDS with sufficient viscosity that defined the thickness and swelling ratio of the stent struts. The thickness of the strut was found to be 338.7 ± 29.3 µm, 262.5 ± 14.7 µm and 237.1 ± 14.7 µm for stents made of SA, SA-CYS and SA-CYS-NF, respectively. SA-CYS-NF stent displayed the highest swelling ratio of 38.8 ± 2.9% at the initial 30 min, whereas stents made of SA and SA-CYS had 23.1 ± 2.4% and 22.0 ± 2.4%, respectively. CONCLUSION: The printed stents had sufficient mechanical strength and were stable against pseudo-physiological wall shear stress. An addition of nanofibers to alginate hydrogel significantly enhanced the biodegradation rates of the stents. In vitro cell culture studies revealed that stents had no cytotoxic effects on human umbilical vein endothelial cells (HUVECs) and Raw 264.7 cells (i.e., Monocyte/macrophage-like cells), supporting that stents are biocompatible and can be explored for future clinical applications.

Development of Man-rGO for Targeted Eradication of Macrophage Ablation.

This study was aimed to develop and evaluate a smart nanosystem that targeted photothermal ablation of inflammatory macrophages in atherosclerotic plaque. Mannosylated-reduced graphene oxide (Man-rGO) was synthesized using three step procedures: (1) preparation of ox-GOs, (2) microwave-assisted synthesis of PEI-rGOs, and (3) mannosylation of PEI-rGO using reductive amination reaction (Man-rGOs). The ζ-potential of Man-rGO that signifies electrophoretic mobility of the charged surface was examined using Zetasizer Nano ZS. The effects of Man-rGO on the cell viability was evaluated using LDH assay and AlamarBlue assay. The targeting efficacy of Man-rGO was assessed using the cellular uptake rate by M2-polarized (i.e., which is induced by IL-4) macrophage. The effects of NOMela loaded in Man-rGO on the enhancement of phagocytosis were evaluated by examining the phagocytic clearance rate of zymosan-FITC particles. The microwave-assisted reduction of GOs was adapted for a facile synthesis of polyethylenimine-reduced GO (PEI-rGO). The mannose functionalization (Man-rGO) of PEI-rGO produced a greater number of amide linkages formed by reductive amination reaction between PEI-rGO and mannose. The ζ-potential of PEI-rGO was +30.6 ± 3.3 mV, whereas that of Man-rGO was down to +13.1 ± 3.8 mV upon interaction with mannose mainly due to the conjugation of mannose on the PEI-rGO surface. Near-infrared (NIR) irradiation increased the temperature of Man-rGO solution to around 45 °C, suggesting that Man-rGO is more potent than ox-GO or rGO in photothermal ablation activity triggered by NIR laser irradiation (808 nm). All testing formulations at the concentrations up to 10 µg/mL exerted less than 10% of membrane disintegration. For AlamarBlue study, more than 90% of cell viability were maintained at the concentrations (up to 10 µg/mL) of all tested formulations. The fluorescent microscopy images of cells after 1 h incubation demonstrated that Man-rGO were mainly accumulated at the subcellular level where the mannose receptors were overexpressed. The cell viability of macrophages significantly decreased upon exposure to Man-rGO irradiated with NIR, but no changes were observed from that of mast cells (for mast cells, 98.3 ± 0.3%; for macrophages, 67.8 ± 1.3%, p < 0.01), indicating that Man-rGO achieved enhanced targetability toward mannose receptor mediated cellular uptake. N-Nitrosomelatonin (NOMela) loaded in macrophage exerted enhanced phagocytic activity. It was concluded that the enhanced photothermal ablation activity of Man-rGO triggered by NIR laser irradiation was mediated through their targetability toward overexpressed mannose receptor, a marker of M2-phenotype of macrophage. The results of this study supported that Man-rGO can serve as an efficient platform for the targeted therapy against atherosclerosis.

Biomimicking Robust Hydrogel for the Mesenchymal Stem Cell Carrier.

PURPOSE: This study was aimed to develop a hydrogel-nanofiber as an advanced carrier for adipose derived human mesenchymal stem cells (AD-MSCs) and evaluate its potential for immunomodulatory therapies applicable to surface coating of drug eluting stent (DES) against coronary artery diseases (CAD). METHODS: A mixture of dispersing-nanofibers (dNFs) and poly (ethylene glycol)-diacrylate (PEGDA) were blended with sodium alginate to achieve robust mechanical strength. The effects of stem cell niche on cell viability and proliferation rates were evaluated using LDH assay and alamar blue assay, respectively. The amount of Nile-red microparticles (NR-MPs) remained in the hydrogel scaffolds was examined as an index for the physical strength of hydrogels. To evaluate the immunomodulatory activity of AD-MSCs as well as their influence by ROS, the level of L-Kynurenine was determined as tryptophan replacement compounds in parallel with IDO secreted from AD-MSCs using a colorimetric assay of L-amino acid. RESULTS: Both SA-cys-PEG and SA-cys-dNF-PEG upon being coated on stents using electrophoretic deposition technique displayed superior mechanical properties against the perfused flow. d-NFs had a significant impact on the stability of SA-cys-dNF-PEG, as evidenced by the substantial amount of NR-MPs remained in them. An enhanced subcellular level of ROS by spheroidal cluster yielded the high concentrations of L-Kynurenine (1.67 ± 0.6 µM without H2O2, 5.2 ± 1.14 µM with 50 µM of H2O2 and 8.8 ± 0.51 µM with 100 µM of H2O2), supporting the IDO-mediated tryptophan replacement process. CONCLUSION: The "mud-and-straw" hydrogels are robust in mechanical property and can serve as an ideal niche for AD-MSCs with immunomodulatory effects.

Advanced cardiovascular stent coated with nanofiber.

Nanofiber was explored as a stent surface coating substance for the treatment of coronary artery diseases (CAD). Nanofibers loaded with nanoparticles containing ß-estradiol were developed and exploited to prevent stent-induced restenosis through regulation of the reactive oxygen species (ROS). Eudragit S-100 (ES), a versatile polymer, was used as a nanoparticle (NP) base, and the mixtures of hexafluoro-2-propanol (HFIP), PLGA and PLA at varying ratios were used as a nanofiber base. ß-Estradiol was used as a primary compound to alleviate the ROS activity at the subcellular level. Nile-Red was used as a visual marker. Stent was coated with nanofibers produced by electrospinning technique comprising the two-step process. Eudragit nanoparticles (ES-NP) as well as 4 modified types of NP-W (ES-NP were dispersed in H2O, which was mixed with HFIP (1:1 (v/v) and then subsequently added with 15% PLGA), NP-HW (ES-NP were dispersed in H2O, which was mixed with HFIP (1:1 (v/v)) already containing 15% PLGA), NP-CHA (ES-NP with a chitosan layer were added in H2O, which was mixed with HFIP (1:1 (v/v)) containing 15% PLGA), and NP-CHB (ES-NP with a chitosan layer were added in H2O, which was mixed with HFIP (1:1 (v/v)) containing the mixture of PLGA and PLA at a ratio of 4:1) were developed, and their properties, such as the loading capacity of ß-estradiol, the release profiles of ß-estradiol, cell cytotoxicity and antioxidant responses to ROS, were characterized and compared. Among composite nanofibers loaded with nanoparticles, NP-CHB had the maximal yield and drug-loading amount of 66.5 ± 3.7% and 147.9 ± 10.1 µg, respectively. The nanofibers of NP-CHB coated on metallic mandrel offered the most sustained release profile of ß-estradiol. In the confocal microscopy study, NP-W exhibited a low fluorescent intensity of Nile-Red as compared with NP-HW, indicating that the stability of nanoparticles decreased, as the percentage volume of the organic solvent increased. Nanofibers incorporated with ß-estradiol yielded a high endothelial proliferation rate, which was about 3-fold greater than the control (without ß-estradiol). The cells treated with the enhanced level of H2O2 (>1 mM: as ROS source) were mostly nonviable (81.1 ± 12.4%, p < 0.01), indicating that ROS induce cell apoptosis and trigger the rupture of atheroma thin layer in a concentration dependent manner. Nanofibers containing ß-estradiol (0.5 mM) lowered cellular cytotoxicity from 25.2 ± 4.9% to 8.1 ± 1.4% in the presence of 600 µM H2O2, and from 86.8 ± 8.4% to 59.4 ± 8.7% in the presence of 1.0 mM H2O2, suggesting that ß-estradiol efficiently protected hPCECs from ROS induced cytotoxicity. The level of NO production in hPCECs in the presence of ß-estradiol after 6 days of incubation was much greater than that of the control without ß-estradiol. In summary, nanofibers loaded with nanoparticles containing ß-estradiol could be used as a suitable platform for the surface coating of a cardiovascular stent, achieving enhanced endothelialization at the implanted sites of blood vessels.

Demonstration of balanced coherent detection using polymer optical waveguide integrated distributed traveling-wave photodetectors.

We have demonstrated balanced coherent detection using distributed balanced traveling-wave photodetectors integrated with single mode polymer optical waveguides. Balanced distributed traveling-wave photodetectors having 3 dB bandwidth of 20 GHz exhibited 20 dB signal to noise ratio improvement measured at 15 GHz modulation frequency in a balanced coherent detection demonstration.

Hormone Therapy and Delivery Strategies against Cardiovascular Diseases.

This review article is aimed to delineate the potential role of hormones in the treatment and diagnosis of cardiovascular diseases with special emphasis on the nitric oxide (NO) involved mechanisms. This review will also offer an overview on current and future hormone usages, pathophysiology, clinical features, absorption mechanisms and adverse effects. The hormone therapies against cardiovascular diseases as well as their treatment strategies, delivery routes and carriers were thoroughly discussed. Ongoing and future basic and clinical research with hormone will provide important insights into efficient treatment strategies against cardiovascular diseases. It was necessary to explore advanced delivery systems, such as drug eluting stent, microneedles, nanotechnology and stem cell preconditioning, for an efficient delivery of hormones against cardiovascular diseases. The future is enlightened with the advent of novel, safer and more effective carriers for hormone delivery as well as learning how to maximize the therapeutic efficacy against cardiovascular diseases.

The physicodynamic properties of mucoadhesive polymeric films developed as female controlled drug delivery system.

To develop an efficient female controlled drug delivery system (FcDDS) against sexually transmitted diseases (STDs), the polymeric films containing sodium dodecyl sulfate (SDS) were prepared with various compositions of Carbopol 934P, hydroxypropyl methylcellulose (HPMC) and polyethylene glycol (PEG). The physicochemical properties of mucoadhesive polymeric films, such as tensile strength, contact angle, swelling ratio and erosion rate in a vaginal fluid stimulant (VFS), were characterized. In addition, the drug release profile of SDS from the films and mucosal residence time were evaluated using a simulated dynamic vaginal system. It was demonstrated that the films made of Carbopol, HPMC and PEG were colorless, thin and soft and had proper physicodynamic properties for FcDDS. An increase in Carbopol content elevated tensile strength and swelling ratio but decreased the contact angle, erosion rate and the SDS release rate from the films. The films containing 0.25% (w/v) PEG as well as 0.75% (w/v) of combining Carbopol and HPMC remained on the vaginal tissue for up to 6h. The films containing the ratio of Carbopol:HPMC:PEG=1.5:1.5:1 and 1:2:1 seem to be optimal compositions for FcDDS, as they showed good peelability, relatively high swelling index and moderate tensile strength, and achieved the target release rate of SDS for 6h.

Inhibition of CEM calcification by the sequential pretreatment with ethanol and EDTA.

The major object of the present study is to optimize the anticalcification activity of ethanol on bioprosthetic heart valve (BHV) calcification. We hypothesize that the chelating agent, in combination with ethanol, will synergistically prevent aortic wall calcification. Collagen-elastin matrix (CEM) was developed as a calcifiable matrix for simulating the calcification process of implantable biomaterials. The efficacy of the combination effects of ethanol and EDTA on the calcification process of CEMs was investigated by implanting them after pretreatment with various conditions of ethanol and EDTA in the rat subdermal model. The relationship between calcium concentrations and pretreatment conditions (a series vs. simultaneous, i.e., first ethanol and then EDTA in water solution, the reverse, or EDTA in ethanol) was established and the optimal condition for prevention of BHV calcification was determined. The mechanistic studies on anticalcification effects exerted by particular pretreatment sequences were also conducted using FTIR and differential scanning calorimetry (DSC). The sequential pretreatment of CEM first with ethanol and then EDTA in water solution significantly decreased the calcification rate of CEM compared the control. The percentage of prevention of calcification by the serial treatment of ethanol (80% v/v) and then EDTA in water solutions decreased, as the concentration of elastin in the CEM increased. The percentage of preventing calcification was 42%, 28.6%, and 22.9% for CEM containing collagen and elastin ratios of 90:10, 50:50, 20:80, respectively. These results indicate that elastin is the major regulatory component of BHV calcification, and preventive effects on calcification increased only when CEM were pretreated with first ethanol and then EDTA in water solution. Moreover, the sequential effect is more apparent in the matrix of less elastin content, which is close to the physiological range. The sequential inhibitory effects of ethanol and EDTA could occur due to the distinct separate actions of each agent, thereby achieving a relatively greater inhibition of calcification.

Biocompatibility of components of a female controlled drug delivery system.

A female controlled drug delivery system (FcDDS) containing sodium dodecyl sulfate as a microbicide, ethylenediaminetetraacetic acid (EDTA) as a synergistic microbicide, and lactic acid as a pH modulator was developed as an intravaginal barrier device against sexually transmitted diseases. The host response of the vagina to the FcDDS was evaluated through biocompatibility tests including cell viability, estrogenicity, and cytotoxicity assays on HeLa cervical cells and NIH:Ovcar-3 ovarian cells. Gel electrophoresis and reverse transcriptase polymerase chain reaction assays on HeLa cervical cell lines were also performed to elucidate the effects of EDTA on the expression of particular proteins of interest. The results of the cell viability test showed no significant difference in viability of cells upon exposure to EDTA at concentrations less than 0.035% that was reported to exert spermicidal activity. EDTA at concentrations less than 0.035% did not cause any cytotoxicity. The results of reverse transcriptase polymerase chain reaction analysis revealed that EDTA induced the expression of a 67-kDa protein in HeLa cells, which was identified as elastin binding protein (a part of the elastin receptor complex). This work has demonstrated that FcDDS containing EDTA is biocompatible and safe to be used as an intravaginal barrier device.

Characterization of a female controlled drug delivery system for microbicides.

In this study, the feasibility of a carbopol 934P-HPMC-based gel formulation as a vaginal drug delivery system was evaluated. A vaginal fluid simulant (VFS) was utilized to simulate human vaginal mucus. The viscosity of the carbopol-HPMC gel system and VFS was examined using a cone and plate viscometer. The surface tension of VFS was measured using a capillary rising method. Differential scanning calorimetry (DSC) was employed to investigate the effect of carbopol gel on the conformational changes of rat vaginal membrane. The viscosity of carbopol gel increased as the pH of the system increased from 4.0 to 6.0. The viscosity of HPMC gel remained the same irrespective of pH of the system. The viscosity of the carbopol gel significantly increased, when HPMC (0.5-1.5%) was added to the system. The optimal viscosity value (1.5-2.0 poises) was achieved at 1.0-1.5% carbopol (pH 4.0) with the presence of 1.0-1.5% HPMC. There were mucin concentration dependent changes in viscosity and surface tension of VFS. The results of DSC analysis of rat vaginal membrane showed that the profiles of thermal stability for both carbopol-treated and the untreated control at the temperature ranging from 40 to 90 degrees C were almost identical. The thermal denaturation temperatures (Td) of the carbopol-treated membrane and the untreated control were not significantly different from each other. The combination of carbopol and HPMC seems to be an ideal formulation as a vaginal delivery system. Mucin played an important role in the regulation of viscosity and surface tension of VFS. DSC study demonstrated that carbopol gel showed good biocompatibility and did not cause any conformational changes in rat vaginal membrane.

Effects of chelating agents on the rheological property of cervical mucus.

As an ongoing effort to elucidate the mechanisms involved in the calcium-dependent fertility regulation process, the viscoelastic properties of the mucus obtained from lamb cervix and human semen, as well as their water and total protein contents after exposure to EDTA, a chelating agent, or Nonoxynol-9 (N-9), a spermicidal agent, were examined. The viscosity was measured using a Cone Plate Digital Viscometer, while the water and total protein contents were determined by the lyophilization process and the Lowry method, respectively. The significant changes in the rheological properties of mucus, such as its viscosity and the water content, upon exposure to EDTA were demonstrated. The viscosity of cervical mucus and human semen were significantly increased by EDTA treatment (as compared to the controls): lamb cervical mucus (2.9 +/- 0.3 vs. 2.2 +/- 0.3 cps) and human semen (5.0 +/- 0.3 vs. 4.3 +/- 0.3 cps), respectively. The hydration rate was decreased by EDTA treatment as compared with the control (93.6 +/- 0.7 vs. 96.8 +/- 0.8%). Among tested samples, the reduction in the percentage of sperm penetration through the cervical mucus was the highest in the mucus containing EDTA, which had the lowest water content (93.6 +/- 0.7%), indicating that there is a positive relationship between the hydration rate of the cervical mucus and its ability to permit the penetration of spermatozoa. This result indicates that spermicidal activity exerted by high concentrations of EDTA is in part due to its effect on the rheological properties of cervical mucus or semen.

Effects of intrinsic variables on release of sodium dodecyl sulfate from a female controlled drug delivery system.

The release profile of sodium dodecyl sulfate (SDS), a potent microbicide, from a female controlled drug delivery system (FcDDS) made of Carbopol 934P and hydroxypropyl methylcellulose (HPMC) was evaluated using a newly developed in vitro Simulant Vaginal System (SVS). The major parameters involved in the release profiles of SDS were categorized as: (1) formulation variables (total loading weight of intravaginal delivery systems, SDS loading doses in intravaginal delivery systems); (2) intrinsic variables (vaginal fluid secretion rate, vaginal fluid pH); and (3) extrinsic variables (inserting position). In most conditions, about 70% of the loading dose of SDS was released from FcDDS within 6h of application. The release profile showed that concentrations needed for complete human papilloma virus (HPV) inactivation could be obtained within 10 min after the application. It was demonstrated that intrinsic variables (i.e., the rate and pH of vaginal fluid) played an integral role in determining the release profile of SDS, while loading dose of SDS in FcDDS did not significantly affect the percentage of the total amount of SDS released. It can be concluded that FcDDS can be exploited as a controlled delivery device for prevention against sexually transmitted diseases.

Preparation and evaluation of bioadhesive benzocaine gels for enhanced local anesthetic effects.

This study was performed to develop new enhanced anesthetic benzocaine gels with a suitable bioadhesive property for local anesthetic effects. As the concentration of benzocaine in the HPMC gels increased up to 15%, the permeation of drug increased, thereafter slightly increased. The activation energy of drug permeation was 11.29 kcal/mol. Bioadhesive forces were also measured. The permeation rate of drug through the skin was studied using various enhancers, such as glycols, non-ionic surfactants or fatty acids. Among the enhancers used, diethylene glycol showed the most enhancing effects. Analgesic activity was examined using a tail-flick analgesimeter. According to the rat tail-flick test, the value of AUEC (0 - 360min) of 15% benzocaine gels containing diethylene glycol was 4662 +/- 200 s min, while that of gels without diethylene glycol was 3353 +/- 132 s min, showing about 1.39-fold increase in analgesic activity. Fifteen percentage of benzocaine gels containing diethylene glycol showed the most enhanced, prolonged analgesic effects, showing the maximum anesthetic effects at 240 min, while the gels without diethylene glycol showed maximum effect at 180 min.

Optimization of cardiovascular stent against restenosis: factorial design-based statistical analysis of polymer coating conditions.

The objective of this study was to optimize the physicodynamic conditions of polymeric system as a coating substrate for drug eluting stents against restenosis. As Nitric Oxide (NO) has multifunctional activities, such as regulating blood flow and pressure, and influencing thrombus formation, a continuous and spatiotemporal delivery of NO loaded in the polymer based nanoparticles could be a viable option to reduce and prevent restenosis. To identify the most suitable carrier for S-Nitrosoglutathione (GSNO), a NO prodrug, stents were coated with various polymers, such as poly (lactic-co-glycolic acid) (PLGA), polyethylene glycol (PEG) and polycaprolactone (PCL), using solvent evaporation technique. Full factorial design was used to evaluate the effects of the formulation variables in polymer-based stent coatings on the GSNO release rate and weight loss rate. The least square regression model was used for data analysis in the optimization process. The polymer-coated stents were further assessed with Differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy analysis (FTIR), Scanning electron microscopy (SEM) images and platelet adhesion studies. Stents coated with PCL matrix displayed more sustained and controlled drug release profiles than those coated with PLGA and PEG. Stents coated with PCL matrix showed the least platelet adhesion rate. Subsequently, stents coated with PCL matrix were subjected to the further optimization processes for improvement of surface morphology and enhancement of the drug release duration. The results of this study demonstrated that PCL matrix containing GSNO is a promising system for stent surface coating against restenosis.

Advanced polymeric matrix for valvular complications.

Poly(L-lactic acid) (PLLA) matrix systems incorporated with poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) containing nitric oxide (NO) donors (DETA NONOate) were developed for prevention of heart valve complications through sustained and controlled release of NO. PLLA matrices were prepared using the salt leaching method and the properties and drug release profiles were characterized. For assessment of the effects of PLLA systems on the pharmacological responses and cytotoxicity, various factors, such as calcium content, alkaline phosphatase (ALP) activity, cyclic guanosine monophosphate (cGMP) expression, intercellular adhesion molecule (ICAM-1) expression and cell viability of porcine aortic valve interstitial cells (PAVICs), were evaluated. PLLA matrices embedded with PLGA- NPs demonstrated its usefulness in alleviating the calcification rate of the VICs. The cGMP levels under osteoblastic conditions significantly increased, supporting that anticalcification activity of NO is mediated through NO-cGMP signaling pathway. The level of ICAM-1 expression in cells exposed to NO was lowered, suggesting that NO has an inhibitory activity against tissue inflammation. NO releases from PLLA matrix embedded with PLGA NPs prevented valvular calcification and inflammation without causing any cytotoxic activities. PLLA matrix system loaded with NPs containing NO donors could provide a new platform for sustained and controlled delivery of NO, significantly reducing valvular complications.

Characterization of nitric oxide delivery systems produced by various nanotechnologies.

Advanced formulations having the capability of long-term protection and preserving the integrity of the nitric oxide molecule were developed for the efficient delivery of nitric oxide. The methods for the production and delivery of nitric oxide produced from diethylenetriamine diazeniumdiolate or S-nitrosoglutathione as a nitric oxide donor to desired target sites in a controlled and sustained release manner are described. The pharmacological assessments of advanced formulations using in vitro and in vivo tests are also described in detail. These systems can be used for the treatment of cardiovascular diseases and sexual dysfunctions.

pH-sensitive Eudragit nanoparticles for mucosal drug delivery.

Drug delivery via vaginal epithelium has suffered from lack of stability due to acidic and enzymatic environments. The biocompatible pH-sensitive nanoparticles composed of Eudragit S-100 (ES) were developed to protect loaded compounds from being degraded under the rigorous vaginal conditions and achieve their therapeutically effective concentrations in the mucosal epithelium. ES nanoparticles containing a model compound (sodium fluorescein (FNa) or nile red (NR)) were prepared by the modified quasi-emulsion solvent diffusion method. Loading efficiencies were found to be 26% and 71% for a hydrophilic and a hydrophobic compound, respectively. Both hydrophilic and hydrophobic model drugs remained stable in nanoparticles at acidic pH, whereas they are quickly released from nanoparticles upon exposure at physiological pH. The confocal study revealed that ES nanoparticles were taken up by vaginal cells, followed by pH-responsive drug release, with no cytotoxic activities. The pH-sensitive nanoparticles would be a promising carrier for the vaginal-specific delivery of various therapeutic drugs including microbicides and peptides/proteins.

Characterization of nitric oxide-releasing microparticles for the mucosal delivery.

For the treatment of female sexual arousal disorder (FSAD), we developed microparticles made of PLGA containing nitric oxide (NO) donor (DETA NONOate) to efficiently deliver NO to vaginal mucosa. The NO-releasing microparticles were prepared by various emulsion methods. SEM and DSC studies were performed to examine the microparticles. The release studies were conducted under various conditions to optimize the loading dose in the microparticles. NO diffusivity through vaginal epithelial cells was evaluated and pharmacological activity of NO-releasing microparticles was examined by assessment of intracellular cGMP level in vaginal cells. Through the modified double emulsion solvent evaporation method (w/o/w(a)), the acid labile DETA NONOate was stabilized during the fabrication process and homogenous morphology and high entrapment efficiency were achieved. DETA NONOate was protected under the acidic conditions of the vagina and NO was released from the microparticles in a controlled manner. A significant amount of NO produced from DETA NONOate penetrated through the vaginal epithelial cells. The intracellular cGMP level increased with the treatment of NO-releasing microparticles in vaginal cells. These findings suggest that NO-releasing microparticles could improve the vaginal blood perfusion and open up the possibilities of novel treatment of FSAD.