Biomedical subjects

Mansoor Amiji

Publications and source records attributed to Mansoor Amiji.

18 recordsLinked to original sources

PubMed2007

Biodistribution and pharmacokinetic analysis of long-circulating thiolated gelatin nanoparticles following systemic administration in breast cancer-bearing mice.

The objective of the present study was to modify thiolated gelatin nanoparticles with poly(ethylene glycol) (PEG) chains and examine their long circulating and tumor-targeting properties in vivo in an orthotopic a human breast adenocarcinoma xenograft model. The crosslinked nanoparticle systems were characterized to have a size of 150-250 nm with rapid payload release properties in a highly reducing environment. Upon PEG modification, the nanoparticle size increased to 300-350 nm in diameter. The presence of PEG chains on the surface was confirmed by characterization with electron spectroscopy for chemical analysis. The in vivo long-circulating potential, biodistribution and passive tumor targeting of the controls, and PEG-modified thiolated gelatin nanoparticles were evaluated by injecting indium-111 (111In)-labeled nanoparticles into breast tumor (MDA-MB-435)-bearing nude mice. Upon modification with PEG, the nanoparticles were found to have longer circulation times, with the plasma and tumor half-lives of 15.3 and 37.8 h, respectively. The results also showed preferential localization of thiolated nanoparticles in the tumor mass. The resulting nanoparticulate systems with long circulation properties could be used to target encapsulated drugs and genes to tumors passively by utilizing the enhanced permeability and retention effect of the tumor vasculature.

Animals↗

PubMed2006

Poly(ethylene oxide)-modified poly(beta-amino ester) nanoparticles as a pH-sensitive system for tumor-targeted delivery of hydrophobic drugs: part 3. Therapeutic efficacy and safety studies in ovarian cancer xenograft model.

PURPOSE: The objective of this study was to evaluate the anti-tumor efficacy and lack of systemic toxicity of paclitaxel when administered in pH-sensitive poly(ethylene oxide) (PEO)-modified poly(beta-amino ester) (PbAE) nanoparticles in mice bearing human ovarian adenocarcinoma (SKOV-3) xenograft. METHODS: Paclitaxel-encapsulated PEO-modified PbAE (PEO-PbAE) nanoparticles were prepared by the solvent displacement method. PEO-modified poly(epsilon-caprolactone) (PCL) (PEO-PCL) nanoparticles were used as a non pH-responsive control formulation. Efficacy studies were conducted in SKOV-3 tumor-bearing athymic (Nu/Nu) mice at an equivalent paclitaxel dose of 20 mg/kg with the control and nanoparticle formulations. Safety of the drug when administered in the control and nanoparticle formulation was determined from blood cell counts and changes in body weight of the animals. RESULTS: The formulated paclitaxel-containing PEO-PbAE and PEO-PCL nanoparticles had a particle size in the range of 100-200 nm and a surface charge of + 39.0 and - 30.8 mV, respectively. After intravenous administration of paclitaxel in these formulations, the tumor growth was inhibited significantly. Both of the formulated nanoparticles tested have shown improved therapeutic efficacy as compared to the paclitaxel aqueous solution. Additionally, significantly lower toxicity profile of paclitaxel was observed with PEO-modified nanoparticles as compared to the aqueous solution formulation CONCLUSION: PEO-modified PbAE nanoparticles are a unique pH-sensitive drug delivery system that elicits enhanced efficacy and safety profile in solid tumor therapy.

Animals↗

PubMed2006

Surface functionalization of gold nanoparticles using hetero-bifunctional poly(ethylene glycol) spacer for intracellular tracking and delivery.

For the development of surface-functionalized gold nanoparticles as cellular probes and delivery agents, we have synthesized hetero-bifunctional poly(ethylene glycol) (PEG, MW 1500) having a thiol group on one terminus and a reactive functional group on the other for use as a flexible spacer. Coumarin, a model fluorescent dye, was conjugated to one end of the PEG spacer and gold nanoparticles were modified with coumarin-PEG-thiol. Surface attachment of coumarin through the PEG spacer decreased the fluorescence quenching effect of gold nanoparticles. The results of cellular cytotoxicity and fluorescence confocal analyses showed that the PEG spacer-modified nanoparticles were essentially non-toxic and could be efficiently internalized in the cells within 1 hour of incubation. Intracellular particle tracking using a Keck 3-D Fusion Microscope System showed that the functionalized gold nanoparticles were rapidly internalized in the cells and localized in the peri-nuclear region. Using the PEG spacer, the gold nano-platform can be conjugated with a variety of biologically relevant ligands such as fluorescent dyes, antibodies, etc in order to target, probe, and induce a stimulus at the target site.

Breast Neoplasms↗

PubMed2005

Poly(ethylene oxide)-modified poly(beta-amino ester) nanoparticles as a pH-sensitive system for tumor-targeted delivery of hydrophobic drugs: part 2. In vivo distribution and tumor localization studies.

PURPOSE: This study was carried out to determine the biodistribution profiles and tumor localization potential of poly(ethylene oxide) (PEO)-modified poly(beta-amino ester) (PbAE) as a novel, pH-sensitive biodegradable polymeric nanoparticulate system for tumor-targeted drug delivery. METHODS: The biodistribution studies of PEO-modified PbAE and PEO-modified poly(epsilon-caprolactone) (PCL), a non-pH-sensitive polymer, nanoparticle systems were carried out in normal mice using 111indium-oxine [111In] as a lipophilic radiolabel encapsulated within the polymeric matrix, and the distribution of the nanoparticles was studied in plasma and all the vital organs following intravenous administration. Solid tumors were developed on nude mice using human ovarian carcinoma xenograft (SKOV-3) and the change in concentrations of tritium [3H]-labeled paclitaxel encapsulated in polymeric nanoparticles was examined in blood, tumor mass, and liver. RESULTS: Study in normal mice with a gamma-emitting isotope [111In] provided a thorough biodistribution analysis of the PEO-modified nanoparticulate carrier systems, whereas 3H-paclitaxel was useful to understand the change in concentration and tumor localization of anticancer compound directly in major sites of distribution. Both PEO-PbAE and PEO-PCL nanoparticles showed long systemic circulating properties by virtue of surface modification with PEO-containing triblock block copolymer (Pluronic stabilizer. Although the PCL nanoparticles showed higher uptake by the reticuloendothelial system, the PbAE nanoparticles effectively delivered the encapsulated payload into the tumor mass. CONCLUSIONS: PEO-modified PbAE nanoparticles showed considerable passive tumor targeting potential in early stages of biodistribution via the enhanced permeation and retention (EPR) mechanism. This prompts a detailed biodistribution profiling of the nanocarrier for prolonged periods to provide conclusive evidence for superiority of the delivery system.

Amino Acids↗

PubMed2005

An approach to heterobifunctional poly(ethyleneglycol) bioconjugates.

A family of differentially substituted poly(ethyleneglycol) building blocks has been assembled from commercially available material. Their utility is demonstrated by formation of amino acid conjugates, image contrast agents, gold nanoparticles, and functional antibody conjugates. Application in the cellular trafficking of antitumoral agent conjugates is expected.

Amino Acids↗

PubMed2005

Tumor-targeted gene delivery using poly(ethylene glycol)-modified gelatin nanoparticles: in vitro and in vivo studies.

PURPOSE: To develop safe and effective systemically administered nonviral gene therapy vectors for solid tumors, DNA-containing poly(ethylene glycol)-modified (PEGylated) gelatin nanoparticles were fabricated and evaluated in vitro and in vivo. METHODS: Reporter plasmid DNA encoding for beta-galactosidase (pCMV-beta) was encapsulated in gelatin and PEGylated gelatin nanoparticles using a water-ethanol solvent displacement method under controlled pH and temperature. Lewis lung carcinoma (LLC) cells in culture were transfected with the pCMV-beta in the control and nanoparticle formulations. Periodically, the expression of beta-galactosidase in the cells was measured quantitatively using an enzymatic assay for the conversion of o-nitrophenyl-beta-D: -galactopyranoside (ONPG) to o-nitrophenol (ONP). Qualitative expression of beta-galactosidase in LLC cells was observed by staining with 5-bromo-4-chloro-3-indolyl-beta-D: -galactopyranoside (X-gal). Additionally, the plasmid DNA-encapsulated gelatin and PEGylated gelatin nanoparticles were administered intravenously (i.v.) and intratumorally (i.t.) to LLC-bearing female C57BL/6J mice. At various time points postadministration, the animals were sacrificed and transgene expression in the tumor and liver was determined quantitatively by the ONPG to ONP enzymatic conversion assay and qualitatively by X-gal staining. RESULTS: Almost 100% of the pCMV-beta was encapsulated in gelatin and PEGylated gelatin nanoparticles (mean diameter 200 nm) at 0.5% (w/w) concentration. PEGylated gelatin nanoparticles efficiently transfected the LLC cells and the beta-galactosidase expression, as measured by the ONPG to ONP enzymatic conversion assay at 420 nm absorbance, increased starting from 12 h until 96 h post-transfection. The efficient expression of LLC cells was also evident by the X-gal staining method that shows blue color formation. The in vivo studies showed significant expression of beta-galactosidase in the tumor following administration of DNA-containing PEGylated gelatin nanoparticles to LLC-bearing mice by both i.v. and i.t. routes. Following i.v. administration of pCMV-beta in PEGylated gelatin nanoparticles, for instance, the absorbance at 420 nm per gram of tumor increased from 0.60 after 12 h to 0.85 after 96 h of transfection. After i.t. administration, the absorbance values increased from 0.90 after 12 h to almost 1.4 after 96 h. CONCLUSIONS: The in vitro and in vivo results of this study clearly show that a long-circulating, biocompatible and biodegradable, DNA-encapsulating nanoparticulate system would be highly desirable for systemic delivery of genetic constructs to solid tumors.

Animals↗

PubMed2005

Cellular interactions and in vitro DNA transfection studies with poly(ethylene glycol)-modified gelatin nanoparticles.

In order to develop a systemically administered safe and effective nonviral gene delivery system, cellular interactions and plasmid DNA transfection with poly(ethylene glycol)-modified (PEGylated) gelatin nanoparticles were examined. The DNA-containing nanoparticles were prepared by a controlled water-ethanol solvent displacement method. The nanoparticles were characterized for particle size, surface charge, and DNA loading, release, and stability. For cellular interaction studies, the control and PEGylated gelatin nanoparticles, complexed either with colloidal gold for transmission electron microscopy or loaded with rhodamine-dextran for fluorescence confocal microscopy, were incubated with NIH-3T3 fibroblast cells. At different time points, the location of the nanoparticles in the cellular environment was investigated. Furthermore, a reporter plasmid expressing the enhanced green fluorescent protein was encapsulated in the control gelatin and PEGylated gelatin nanoparticles for in vitro transfection studies. DNA-containing nanoparticles were prepared in the size range of 100-500 nm, with an average of 200 nm. PEGylated gelatin nanoparticles, with a slight negative surface charge, could stably and efficiently encapsulate plasmid DNA. Both transmission electron microscopy and confocal microscopy images showed that the gelatin and PEGylated gelatin nanoparticles rapidly entered the cell through nonspecific endocytosis followed by vesicular transport in the cytosol. Almost 100% of the administered gelatin and PEGylated gelatin nanoparticles were internalized in NIH-3T3 cells within the first 6 h of incubation. A large fraction of the administered nanoparticles was found to be concentrated in the perinuclear region of the cells after 12 h. Green fluorescent protein expression was observed after 12 h of nanoparticle incubation and remained stable for up to 96 h. Flow cytometry results showed that the DNA transfection efficiency with gelatin and PEGylated gelatin nanoparticles was 43% and 61%, respectively, after 96 h. The results of this study illustrate that PEGylated gelatin nanoparticles were rapidly internalized by the cells through nonspecific endocytosis and remained intact in the cytosol for up to 12 h. In addition, the DNA-encapsulated PEGylated gelatin nanoparticles were found to efficiently transfect cells in culture.

3T3 Cells↗

PubMed2004

Stomach-specific anti-H. pylori therapy; part III: effect of chitosan microspheres crosslinking on the gastric residence and local tetracycline concentrations in fasted gerbils.

The main objective of the present study was to examine the effect of chemical crosslinking of chitosan microspheres on the gastric residence and local tetracycline concentrations following oral administration in fasted gerbils. Radioiodinated [125I] glyoxal-crosslinked chitosan microsphere suspension in deionized distilled water was administered for the gastric residence studies. At different time points, the animals were sacrificed and the radioactivity in tissues and fluids was measured. Stomach tetracycline concentrations were determined using tritiated-[3H]-tetracycline-loaded crosslinked chitosan microspheres. The radioactivity, measured with a liquid scintillation analyzer, was used to determine the microgram of drug per gram of tissues or fluids. After 2 h in the fasted stomach, approximately 10% of the non-crosslinked chitosan microspheres remained. On the other hand, 17% of the crosslinked chitosan microspheres remained in the fasted stomach after the same time period. The microspheres were predominantly found in the colon after 6 h of administration. There was no detectable radioactivity in the plasma, urine, small intestine, liver, and kidneys. Tetracycline concentration profile in the stomach from the crosslinked microsphere formulation was higher than that of the aqueous solution and the non-crosslinked microsphere formulation. While the area-under-the-curve (AUC(0.5-->10 h)) for tetracycline solution and non-crosslinked chitosan microspheres was 447.3 and 358.2 microg h/g of tissue, respectively, the AUC(0.5-->10 h) for the crosslinked chitosan microspheres was 868.9 microg h/g of tissue. The drug was predominantly found in the colon and urine after 6 h of administration. Results of this study show that chitosan microspheres prepared by chemical crosslinking provide a longer residence time in the fasted gerbil stomach than either tetracycline solution or microspheres prepared by ionic precipitation.

Administration, Oral↗

PubMed2004

Enzyme immobilization in novel alginate-chitosan core-shell microcapsules.

Alginate-chitosan core-shell microcapsules were prepared in order to develop a biocompatible matrix for enzyme immobilization, where the protein is retained either in a liquid or solid core and the shell allows permeability control over substrates and products. The permeability coefficients of different molecular weight compounds (vitamin B2, vitamin B12, and myoglobin) were determined through sodium tripolyphosphate (Na-TPP)-crosslinked chitosan membrane. The microcapsule core was formed by crosslinking sodium alginate with either calcium or barium ions. The crosslinked alginate core was uniformly coated with a chitosan layer and crosslinked with Na-TPP. In the case of calcium alginate, the phosphate ions of Na-TPP were able to extract the calcium ions from alginate and liquefy the core. A model enzyme, beta-galactosidase, was immobilized in the alginate core and the catalytic activity was measured with o-nitrophenyl-beta-D-galactopyranoside (ONPG). Change in the activity of free and immobilized enzyme was determined at three different temperatures. Na-TPP crosslinked chitosan membranes were found to be permeable to solutes of up to 17,000Da molecular weight. The enzyme loading efficiency was higher in the barium alginate core (100%) as compared to the calcium alginate core (60%). The rate of ONPG conversion to o-nitrophenol was faster in the case of calcium alginate-chitosan microcapsules as compared to barium alginate-chitosan microcapsules. Barium alginate-chitosan microcapsules, however, did improve the stability of the enzyme at 37 degrees C relative to calcium alginate-chitosan microcapsules or free enzyme. This study illustrates a new method of enzyme immobilization for biotechnology applications using liquid or solid core and shell microcapsule technology.

Alginates↗

PubMed2004

Biodistribution and targeting potential of poly(ethylene glycol)-modified gelatin nanoparticles in subcutaneous murine tumor model.

PURPOSE: In order to develop a safe and effective systemically-administered biodegradable nanoparticle delivery system for solid tumors, the comparative biodistribution profiles of gelatin and poly(ethylene-glycol)(PEG)-modified (PEGylated) gelatin nanoparticles was examined in subcutaneous Lewis lung carcinoma (LLC)-bearing female C57BL/6J mice. METHODS: Type-B gelatin and PEGylated gelatin nanoparticles were radiolabeled ((125)I) for the in vivo biodistribution studies after intravenous (i.v.) administration through the tail vein in LLC-bearing mice. At various time intervals, the mice were sacrificed and blood, tumor, and major organs harvested for analysis of radioactivity corresponding to the localization of the nanoparticles. Percent recovered dose was determined and normalized to the weight of the fluid or tissue sample. Non-compartmental pharmacokinetic analysis was performed to determine the long-circulating property and preferential tumor targeting potential of PEGylated gelatin nanoparticles in vivo. RESULTS: From the radioactivity in plasma and various organs collected, it was evident that the majority of PEGylated nanoparticles were present either in the blood pool or taken up by the tumor mass and liver. For instance, after 3 h, the concentrations of PEGylated gelatin nanoparticles was almost 2-fold higher in the blood pool than the control gelatin nanoparticles. PEGylated gelatin nanoparticles remained in the blood pool for a longer period of time due to the steric repulsion effect of the PEG chains as compared to the gelatin nanoparticles. In addition, approximately 4-5% of the recovered dose of PEGylated gelatin nanoparticles was present in the tumor mass for up to 12 h. The plasma and the tumor half-lives, the mean residence time, and the area-under-the-curve of the PEGylated gelatin nanoparticles were significantly higher than those for the gelatin nanoparticles. CONCLUSIONS: The results of this study show that PEGylated gelatin nanoparticles do possess long circulating properties and can preferentially distribute in the tumor mass after systemic delivery.

Animals↗

PubMed2004

Poly-N-acetyl glucosamine-mediated red blood cell interactions.

BACKGROUND: Investigations were performed to assess the effect of poly-N-acetyl glucosamine (p-GlcNAc) fiber slurry-mediated hemostasis by interactions with red blood cells. METHODS: Red blood cell aggregation studies were performed using test material-coated microscope slides and multiphoton microscopic measurements. Enzymatic removal of red blood cell surface proteins was achieved using trypsin and neuraminidase treatment. Zeta-potential measurements (surface charge) were performed. RESULTS: Red blood cells interact directly with poly-N-acetyl glucosamine polymers through ionic interactions and cell-surface proteins. The effective concentration of poly-N-acetyl glucosamine fiber material for 50% red blood cell aggregation was 0.28 mg/mL. The p-GlcNAc beta-configuration fibers and an alpha-configuration structural modification of the fibers both produced maximal responses because of their zeta-potentials, whereas other chemically modified p-GlcNAcs and chitosans were ineffective. CONCLUSION: Poly-N-acetyl glucosamine-induced red blood cell aggregation is mediated by interactions with red blood cell surface charges.

Acetylglucosamine↗

PubMed2003

Chitosan-based gastrointestinal delivery systems.

Chitosan, a natural polymer obtained by alkaline deacetylation of chitin, is non-toxic, biocompatible, and biodegradable. These properties make chitosan a good candidate for the development of conventional and novel gastrointestinal (GI) drug and gene delivery systems. The objective of this review is to summarize the recent applications of chitosan in oral and/or buccal delivery, stomach-specific drug delivery, intestinal delivery, and colon-specific drug delivery. The use of chitosan for targeting of drugs to each of these sites in the GI tract is illustrated by examples supported by in vivo studies. Chitosan appears to be a promising material for GI drug and gene delivery applications as many derivatives and formulations are being examined.

Animals↗

PubMed2003

Stomach-specific anti-H. pylori therapy. II. Gastric residence studies of tetracycline-loaded chitosan microspheres in gerbils.

This study examines the gastric residence of chitosan microspheres and the local tetracycline concentrations following oral administration in gerbils. Chitosan microspheres were prepared by ionic cross-linking and precipitation with sodium sulfate. Gastric retention studies were performed by administering radioiodinated [125I] chitosan microsphere suspension in the nonacid-suppressed and acid-suppressed states. At different time points, animals were sacrificed, and the radioactivity in tissues and fluids was measured with a gamma counter. Local tetracycline concentrations were measured using chitosan microspheres loaded with tritiated-[3H]-tetracycline. The radioactivity, measured with a liquid scintillation analyzer, was used to determine the microg of drug per gram of tissues or fluids under nonacid-suppressed and acid-suppressed states. Microspheres with a spherical shape and an average diameter of 2.0-3.0 microm were formed. After 2 hr in the fasted stomach, approximately 10% of the administered dose remained. The microspheres were predominantly found in the colon after 6 hr of administration. There was no detectable radioactivity in the small intestine, plasma, urine, liver, and kidneys. Additionally, acid suppression with ranitidine did not influence the gastric residence time of chitosan microspheres. To our disappointment, tetracycline concentration profile in the stomach from microsphere formulation was similar to the aqueous solution. Also, there was no significant difference between the stomach tetracycline concentrations in the nonacid-suppressed and acid-suppressed states. The drug was predominantly found in the colon and urine samples after 6 hr. Tetracycline could not be detected in the plasma, small intestine, liver, or kidneys. Results of this study show that chitosan microspheres prepared by ionic cross-linking do not provide a longer residence time in the fasted gerbil stomach. The tetracycline concentration profile in the stomach, following administration in microsphere formulation, was similar to that of aqueous solution. Lastly, acid suppression did not influence the gastric residence time of chitosan microspheres or tetracycline concentration profiles.

Animals↗

PubMed2002

Stomach-specific anti-H. pylori therapy. I: Preparation and characterization of tetracyline-loaded chitosan microspheres.

The main objective of the study was to develop a stomach-specific drug delivery system to increase the efficacy of tetracycline against Helicobacter pylori. Chitosan microspheres were prepared by ionic cross-linking and precipitation with sodium sulfate. Two different methods were used for drug loading. In method I, tetracycline was mixed with chitosan solution before the simultaneous cross-linking and precipitation. In method II, the drug was incubated with pre-formed microspheres for 48 h. The cumulative amount of tetracycline that was released from chitosan microspheres and the stability of the drug was examined in different pH medium at 37 degrees C. Microspheres with a spherical shape and an average diameter of 2.0-3.0 microm were formed. When the drug was added to the polymer solution before cross-linking and precipitation only 8% (w/w) was optimally incorporated in the final microsphere formulation. When the drug was incubated with the pre-formed microspheres, on the other hand, a maximum of 69% (w/w) could be loaded. Thirty percent of tetracycline either in solution or when released from microspheres was found to degrade at pH 1.2 in 12 h. The preliminary results from this study suggest that chitosan microspheres can be used to incorporate antibiotic drugs and may be effective when administered locally in the stomach against H. pylori.

Anti-Bacterial Agents↗

PubMed2002

Localized delivery of paclitaxel in solid tumors from biodegradable chitin microparticle formulations.

Paclitaxel (Taxol)-containing chitin and chitin-Pluronic F-108 microparticles were formulated as biodegradable systems for localized administration in solid tumors. The microparticles were characterized by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and swelling studies in phosphate-buffered saline (PBS, pH 7.4). Lysozyme-induced degradation and in vitro release of paclitaxel was examined in PBS at 37 degrees C. The percent change in tumor volume was used to assess efficacy of the Formulations after local administration in murine Lewis lung carcinoma model. FT-IR confirmed higher degree of acetylation in chitin microparticles from the starting chitosan sample and the SEM showed that the chitin-Pluronic F-108 microparticles were significantly more porous than chitin microparticles. Due to higher porosity, chitin-Pluronic microparticles were able to imbibe higher swelling medium and degraded much faster in the presence of lysozyme than chitin microparticles. After 48 h. 51% of incorporated paclitaxel was released from chitin-Pluronic microparticles as compared to 28% from chitin microparticles. In vivo studies in Lewis lung carcinoma-bearing mice showed that the tumor volumes after 6 days using paclitaxel-loaded chitin and chitin-Pluronic F-108 microparticles was 458 and 307 mm3, respectively. In contrast, the tumor volume was 997 mm3 for the untreated control. The results of this study show that chitin and chitin-Pluronic F-108 microparticles are biodegradable drug delivery systems that can be useful for localized delivery of paclitaxel in solid tumors.

Acetylglucosamine↗

PubMed2002

Long-circulating poly(ethylene glycol)-modified gelatin nanoparticles for intracellular delivery.

PURPOSE: The objective of this study was to develop and characterize long-circulating, biodegradable, and biocompatible nanoparticulate formulation as an intracellular delivery vehicle. METHODS: Poly(ethylene glycol) (PEG)-modified gelatin was synthesized by reacting Type-B gelatin with PEG-epoxide. The nanoparticles, prepared by pH and temperature controlled ethanol-water solvent displacement technique, were characterized for mean size, size distribution, and surface morphology. Electron spectroscopy for chemical analysis (ESCA) was used to confirm the surface presence of PEG chains. In vitro release of tetramethylrhodamine-labeled dextran (TMR-dextran, Mol. wt. 10,000 daltons) from the nanoparticle formulations was examined in PBS, with and without 0.2-mg/ml protease, at 37 degrees C. Relative cytotoxicity profile of control and PEGylated gelatin was evaluated in BT-20 a human breast cancer cell line. The nanoparticles were incubated with BT-20 cells to determine uptake and cellular distribution using confocal microscopy. RESULTS: Gelatin and PEGylated gelatin nanoparticles were found to be spherical in shape with a smooth surface in a size range of 200-500 nm and a unimodal size distribution. ESCA results showed an increase in the ether carbon (-C-O-) peak in the PEGylated gelatin nanoparticles due to the presence of PEG chains. The presence of PEG chains decreased the percent release of TMR-dextran in the presence of proteolytic enzyme due to steric repulsion. Cytotoxicity assays indicated that both gelatin and PEGylated gelatin were completely non-toxic to the cells. A large fraction of the administered control gelatin and PEGylated gelatin nanoparticles were found to be concentrated in the perinuclear region of the BT-20 cells after 12 hours indicating possible vesicular transport through initial uptake by endocytosis and endosomal processing. CONCLUSION: The results of this study show that PEGylation of gelatin may prove beneficial as long-circulating delivery system in vivo. Additionally, the nanoparticles could encapsulate hydrophilic macromolecules and are internalized by tumor cells.

Delayed-Action Preparations↗

PubMedDate not supplied

Preparation and evaluation of thiol-modified gelatin nanoparticles for intracellular DNA delivery in response to glutathione.

To enhance the intracellular delivery potential of plasmid DNA using nonviral vectors, we have developed thiolated gelatin nanoparticles that can release the payload in the highly reducing environment, such as in response to glutathione. Thiolated gelatin was synthesized by covalent modification of the primary amino groups of Type B gelatin using 2-iminothiolane (Traut's reagent). The degree of thiolation of the polymers ranged from 0 to 43.71 mmol of reduced sulfhydryl (SH) groups when the amount of 2-iminothiolane was increased up to 100 mg per gram of the biopolymer. Cytotoxicity evaluations carried out by the formazan (MTS) assay showed that the thiolated gelatin prepared with 20 mg and 40 mg of 2-iminothiolane (SHGel-20 and SHGel-40) per gram of gelatin had comparable cell viability profile to that of the unmodified gelatin. In vitro release studies of fluorescein isothiocyanate (FITC)-labeled dextran (mol wt. 70 000 Da), when encapsulated in gelatin and thiolated gelatin nanoparticles (150-250 nm in diameter), was found to be affected by the presence of glutathione (GSH) in the medium. The presence of GSH was found to enhance the release by about 40% in case of thiolated gelatin and about 20% in gelatin nanoparticles under similar conditions of temperature and GSH concentrations. Qualitative and quantitative analysis of transfection in NIH-3T3 murine fibroblast cells by the nanoparticles carrying plasmid DNA encoding for enhanced green fluorescent protein (EGFP-N1) was done by fluorescence confocal microscopy and fluorescence-activated cell sorting (FACS). Qualitative results showed highly efficient expression of GFP that remained stable for up to 96 h. Quantitative results from FACS showed that the thiolated gelatin nanoparticles (SHGel-20) were significantly more effective in transfecting NIH-3T3 cells than other carrier systems examined. The results of this study show that thiolated gelatin nanoparticles would serve as a biocompatible intracellular delivery system that can release the payload in a highly reducing environment.

3T3 Cells↗

PubMedDate not supplied

Poly(ethylene oxide)-modified poly(beta-amino ester) nanoparticles as a pH-sensitive system for tumor-targeted delivery of hydrophobic drugs. 1. In vitro evaluations.

A representative poly(beta-amino ester) (PbAE) with biodegradable and pH-sensitive properties was used to formulate a nanoparticle-based dosage form for tumor-targeted paclitaxel delivery. The polymer undergoes rapid dissolution when the pH of the medium is less than 6.5 and hence is expected to release its contents at once within the acidic tumor microenvironment and endo/lysosome compartments of cells. PbAE nanoparticles were prepared by solvent displacement method and characterized for particle size, charge, and surface morphology. Pluronic F-108, a triblock copolymer of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO), was blended with PbAE to induce surface modification of the nanoparticles. In vitro cellular uptake of tritiated [(3)H]-paclitaxel in solution form and as a nanoparticulate formulation was studied in MDA-MB-231 human breast adenocarcinoma cells grown in 12-well plates. We also examined the intracellular degradation pattern of the formulations within the cells by estimating the drug release profile. Cytotoxicity assay was performed on the formulations at different doses and time intervals. Nanoparticles prepared from poly(epsilon-caprolactone) (PCL) that do not display pH-sensitive release behavior were used as control. Spherical nanoparticles having positive zeta potential ( approximately 40 mV) were obtained in the size range of 150-200 nm with PbAE. The PEO chains of the Pluronic were well-anchored within the nanomatrix as determined by electron spectroscopy for chemical analysis (ESCA). The intracellular accumulation of paclitaxel within tumor cells was significantly higher when administered in the nanoparticle formulations as compared to aqueous solution. Qualitative fluorescent microscopy confirmed the rapid release of the payload into the cytosol in the case of PbAE nanoparticles, while the integrity of the PCL nanoparticles remained intact. The cytotoxicity assay results showed significantly higher tumoricidal activity of paclitaxel when administered in the nanoparticle formulations. The cell-kill effect was maximal for paclitaxel-loaded PbAE nanoparticles when normalized with respect to intracellular drug concentrations. Thus, PEO-modified PbAE nanoparticles show tremendous potential as novel carriers of cytotoxic agents for achieving improved drug disposition and enhanced efficacy.

Cell Line, Tumor↗