Biomedical subjects

Vinod Labhasetwar

Publications and source records attributed to Vinod Labhasetwar.

At least 19 recordsLinked to original sources

PubMed2006

Polymeric nanoparticles for gene delivery.

Since the evolution of the concept of gene therapy, delivering therapeutic genes to the diseased cells has been a major challenge. Although viral vectors have been shown to be efficient in delivering genes, the issue of their safety is still to be solved. Meanwhile, the field of developing nonviral expression vectors has seen considerable progress. As compared with viruses, these are relatively safe but are confronted with the problem of poor transfection efficiency. With the growing understanding of the biology of gene transfection, and the continued efforts at enhancing the efficiency of nonviral expression vectors, it could soon become a preferred option for human gene therapy. In this review, the potential of polymeric nanoparticles as a gene expression vector is discussed. Furthermore, the importance of understanding the pathophysiology of disease conditions in developing gene expression vectors is discussed in Section 6.

Animals↗

PubMed2005

Nanotechnology for drug and gene therapy: the importance of understanding molecular mechanisms of delivery.

Nanotechnology, although not a new concept, has gained significant momentum in recent years. This stems partly from the realization that nanosystems have significantly different biological properties from large-sized systems (e.g. implants or microparticles) that could be used effectively to overcome problems in drug and gene therapy. In drug therapy, we face the problems of inefficacy or nonspecific effects; hence, nanosystems are being developed for targeted drug therapy. In gene therapy using non-viral systems, the main issues are relatively transient gene expression and lower efficiency than viral vectors. Research efforts have focused on understanding the barriers in gene delivery so that non-viral systems can be developed that are as effective as viral systems in gene transfection. Understanding the molecular mechanisms that underlie the interactions of nanosystems with the cell, their uptake properties and retention will be crucial for the successful development of these systems.

Animals↗

PubMed2005

Targeted drug delivery in cancer therapy.

Chemotherapy has been the main modality of treatment for cancer patients; however, its success rate remains low, primarily due to limited accessibility of drugs to the tumor tissue, their intolerable toxicity, development of multi-drug resistance, and the dynamic heterogeneous biology of the growing tumors. Better understanding of tumor biology in recent years and new targeted drug delivery approaches that are being explored using different nanosystems and bioconjugates provide optimism in developing successful cancer therapy. This article reviews the possibilities and challenges for targeted drug delivery in cancer therapy.

Animals↗

PubMed2004

Efficacy of transferrin-conjugated paclitaxel-loaded nanoparticles in a murine model of prostate cancer.

Chemotherapy remains the preferred choice of treatment for prostate cancer but modest drug response and significant toxicity by conventional methods of administration limit their efficacy. In our study, we determined the efficacy of paclitaxel (Tx)-loaded biodegradable nanoparticles (NPs) on tumor inhibition. We hypothesized that NPs following conjugation to transferrin (Tf) ligand (NPs-Tf) would enhance the therapeutic efficacy of the encapsulated drug. The antiproliferative activity of NPs was determined in human prostate cancer cell line (PC3) and their effect on tumor inhibition in a murine model of prostate cancer. NPs (approximately 220 nm in diameter, 5.4% w/w drug loading) under in vitro conditions exhibited sustained release of the encapsulated drug (60% release in 60 days). The IC50 (concentration of drug for 50% inhibition of cell growth) of the drug with Tf-conjugated NPs (Tx-NPs-Tf) was about 5-fold lower than that with unconjugated NPs (Tx-NPs) or drug in solution. Animals that received a single-dose intratumoral injection of Tx-NPs-Tf (Tx dose= 4 mg/kg) demonstrated complete tumor regression and greater survival rate than those that received either Tx-NPs or Tx-Cremophor EL formulation. In conclusion, sustained release NPs demonstrated greater antitumor activity following their conjugation to Tf ligand.

Animals↗

PubMed2004

Sustained cytoplasmic delivery of drugs with intracellular receptors using biodegradable nanoparticles.

Efficient cytoplasmic delivery of therapeutic agents is especially important for drugs with an intracellular site of action for elicitation of a maximal therapeutic effect. In this study, we demonstrate the efficacy of biodegradable nanoparticles for cytoplasmic delivery of dexamethasone, a glucocorticoid, whose site of action is intracellular. Equal doses of two formulations of drug-loaded nanoparticles releasing different doses of the encapsulated drug were tested for antiproliferative activity in vascular smooth muscle cells. The antiproliferative activity of the drug was significantly greater and sustained with nanoparticles that released a higher dose of the drug than with nanoparticles which released a lower dose of the drug. The greater antiproliferative activity of the nanoparticles that released a higher dose of the drug correlated with sustained and higher intracellular drug levels. The antiproliferative activity of the drug in solution was lower and relatively transient compared to that with drug-loaded nanoparticles. The mechanism of inhibition of cell proliferation was mediated through inhibition of cell-cycle progression with a relatively higher percentage of cells in the G0/G1 arrest phase in the group that was treated with drug-loaded nanoparticles compared to that treated with the drug in solution. Results of the study thus suggest that the dose and duration of a drug's availability at the intracellular site of action determine its therapeutic efficacy. In conclusion, biodegradable nanoparticles could be used as an effective delivery mechanism for sustained intracellular delivery of different therapeutic agents.

Apoptosis↗

PubMed2004

Solid-state solubility influences encapsulation and release of hydrophobic drugs from PLGA/PLA nanoparticles.

Biodegradable nanoparticles formulated from poly(D,L-lactide-co-glycolide) (PLGA) and polylactide (PLA) polymers are being extensively investigated for various drug delivery applications. In this study, we hypothesize that the solid-state solubility of hydrophobic drugs in polymers could influence their encapsulation and release from nanoparticles. Dexamethasone and flutamide were used as model hydrophobic drugs. A simple, semiquantitative method based on drug-polymer phase separation was developed to determine the solid-state drug-polymer solubility. Nanoparticles using PLGA/PLA polymers were formulated using an emulsion-solvent evaporation technique, and were characterized for size, drug loading, and in vitro release. X-ray powder diffraction (XRD) and differential scanning calorimetry (DSC) were used to determine the physical state of the encapsulated drug. Results demonstrated that the solid-state drug-polymer solubility depends on the polymer composition, molecular weight, and end-functional groups (ester or carboxyl) in polymer chains. Higher solid-state drug-polymer solubility resulted in higher drug encapsulation in nanoparticles, but followed an inverse correlation with the percent cumulative drug released. The XRD and DSC analyses demonstrated that the drug encapsulated in nanoparticles was present in the form of a molecular dispersion (dissolved state) in the polymer, whereas in microparticles, the drug was present in both molecular dispersion and crystalline forms. In conclusion, the solid-state drug-polymer solubility affects the nanoparticle characteristics, and thus could be used as an important preformulation parameter.

Drug Compounding↗

PubMed2004

A novel approach for cancer immunotherapy: tumor cells with anchored superantigen SEA generate effective antitumor immunity.

Murine B16 melanoma cell line is poorly immunogenic and highly aggressive. We recently reported that the transmembrane staphylococcal enterotoxin A (TM-SEA) anchors onto B16 cells and stimulates lymphocyte proliferation. The purpose of the study was to investigate whether vaccination with B16 cells bearing membrane-anchored TM-SEA fusion protein could cause tumor-specific immunity. Mice in the therapeutic vaccination group received B16 tumor inoculations, followed by treatment with B16-TM-SEA vaccine or control vaccines. Mice in the prophylactic vaccination group were given B16-TM-SEA vaccine or control vaccines, followed by challenge with wild type B16 or control EL4 cells. Significant tumor growth inhibition, prolongation of survival, and marked augmentation of NK and CTL activities were observed in mice which received B16-TM-SEA vaccine as compared to controls. Overall, our results suggest that the TM-SEA cellular vaccine is a novel and effective strategy for cancer immunotherapy.

Animals↗

PubMed2004

Critical determinants in PLGA/PLA nanoparticle-mediated gene expression.

PURPOSE: The aim of the study was to determine the critical determinants in nanoparticle-mediated gene transfection. It was hypothesized that different formulation parameters could affect the nanoparticle characteristics and hence its gene transfection. METHODS: Nanoparticles encapsulating plasmid DNA encoding for firefly luciferase were formulated using polylactide (PLA) and poly (D,L-lactide-co-glycolide) (PLGA) polymers of different compositions and molecular weights. A multiple-emulsion solvent-evaporation method with polyvinyl alcohol (PVA) as an emulsifier was used to formulate DNA-loaded nanoparticles. Gene expression of nanoparticles was determined in breast cancer (MCF-7) and prostate cancer (PC-3) cell lines. RESULTS: Nanoparticles formulated using PLGA polymer demonstrated greater gene transfection than those formulated using PLA polymer, and this was attributed to the higher DNA release from PLGA nanoparticles. Higher-molecular-weight PLGA resulted in the formation of nanoparticles with higher DNA loading, which demonstrated higher gene expression than those formulated with lower-molecular-weight PLGA. In addition, the nanoparticles with lower amount of surface-associated PVA demonstrated higher gene transfection in both the cell lines. Higher gene transfection with these nanoparticles was attributed to their higher intracellular uptake and cytoplasmic levels. Further study demonstrated that the molecular weight and the degree of hydrolyzation of PVA used as an emulsifier also affect the gene expression of nanoparticles. CONCLUSIONS: Results thus demonstrate that the DNA loading in nanoparticles and its release, and the surface-associated PVA influencing the intracellular uptake and endolysosomal escape of nanoparticles, are some of the critical determinants in nanoparticle-mediated gene transfection.

Animals↗

PubMed2004

The characteristics and mechanisms of uptake of PLGA nanoparticles in rabbit conjunctival epithelial cell layers.

PURPOSE: To delineate the characteristics and mechanisms of uptake of biodegradable poly(D,L-lactide-co-glycolide) (PLGA) nanoparticles in primary cultured rabbit conjunctival epithelial cells (RCECs). METHODS: Poly(D,L-lactide-co-glycolide) nanoparticles (PLGA 50:50. 101 nm in diameter) containing 6-coumarin (as a fluorescent marker) were used. The effect of size was studied using various particle sizes (100 nm, 800 nm, and 10 microm). The effect of cytochalasin D, nocodazole, and metabolic inhibitors on nanoparticle uptake was investigated. The capability of nanoparticles to enhance the uptake of an encapsulated protein. BSA bound to Texas red (TR-BSA), was evaluated. RESULTS: Maximal uptake of nanoparticles at 37 degrees C occurred at 2 h, and 100-nm particles had the highest uptake in RCECs in comparison with 800-nm and 10-microm particles. Nanoparticle uptake was saturable over the 0.1-4 mg/ml concentration range. Nanoparticle uptake was confirmed by confocal microscopy and was inhibited significantly by coumarin-free nanoparticles (of similar size), by lower incubation temperature, and by the presence of metabolic inhibitors and cytochalasin D. The uptake of encapsulated TR-BSA in RCECs at 4 h was 28% higher than free BSA application. CONCLUSION: Our findings suggest that PLGA nanoparticle uptake in primary cultured rabbit conjunctival epithelial cells occurs most likely by adsorptive-type endocytosis.

Animals↗

PubMed2004

Targeting intracellular targets.

Many therapeutic agents have intracellular compartments as their site of action. Targeted delivery of these agents to their specific intracellular targets could result in enhanced therapeutic efficacy and reduced toxicity. Various carriers have been shown useful in targeted delivery of different classes of therapeutic agents. Among these carriers, biodegradable nanoparticles formulated from biocompatible polymers poly(D,L-lactide-co-glycolide) (PLGA) and polylactide (PLA) have shown the potential for sustained intracellular delivery of different therapeutic agents. In this review, we discuss different intracellular targets, barriers to intracellular delivery, mechanism and pathways of intracellular delivery, and various carriers and approaches that have been investigated for intracellular drug delivery.

Animals↗

PubMed2003

Nanotech approaches to drug delivery and imaging.

Nanotechnology, a multidisciplinary scientific undertaking, involves creation and utilization of materials, devices or systems on the nanometer scale. The field of nanotechnology is currently undergoing explosive development on many fronts. The technology is expected to create innovations and play a critical role in various biomedical applications, not only in drug delivery, but also in molecular imaging, biomarkers and biosensors. Target-specific drug therapy and methods for early diagnosis of pathologies are the priority research areas where nanotechnology would play a vital role. This review considers different nanotechnology-based drug delivery and imaging approaches, and their economic impact on pharmaceutical and biomedical industries.

Drug Delivery Systems↗

PubMed2003

Clathrin and caveolin-1 expression in primary pigmented rabbit conjunctival epithelial cells: role in PLGA nanoparticle endocytosis.

PURPOSE: The internalization of poly (dl-lactide-co-glycolide, PLGA) nanoparticles in rabbit conjunctival epithelial cells (RCEC) was previously shown to occur by an endocytic process, as evidenced its energy-dependence, inhibition by the vesicle formation blocker cytochalasin D, and by the characteristic display of punctate distribution under confocal microscopy. In addition, clathrin protein was implicated in the endocytosis of these nanoparticles in vascular smooth muscle cells. We sought to examine the expression of clathrin and caveolin-1 in RCECs and to determine whether they play a role in PLGA nanoparticle endocytosis. METHODS: PLGA (50:50) nanoparticles (100 nm in diameter) containing 6-coumarin (fluorescent marker, 0.05% w/v) were used in this study. The effect of pharmacological treatments aimed at disrupting formation of clathrin-coated vesicles (hypertonic challenge and intracellular K+ depletion) and caveolae (nystatin and filipin) on apical uptake of nanoparticles in primary cultured RCEC was investigated. Transferrin was chosen as a marker for clathrin-dependent endocytosis from the basolateral aspect, whereas cholera toxin B subunit was chosen as a marker for caveolae-mediated endocytosis. The staining pattern of nanoparticles in RCECs was compared with that of clathrin heavy chain (HC) and caveolin-1 under fluorescent confocal microscopy to examine possible colocalization using clathrin HC and caveolin-1 mouse monoclonal antibodies (mAb). Two pairs of primers were designed (based on conserved regions of clathrin and caveolin-1 gene in different species) to amplify a 744-bp and 152-bp fragment of clathrin HC and caveolin-1 gene, respectively. Reverse transcription-polymerase chain reaction (RT-PCR) to detect the message for clathrin HC and caveolin-1 was performed using total RNA prepared from freshly isolated RCECs. HEK293 cells were used as positive control for clathrin gene expression, whereas rabbit heart muscle and HEK cells were used as positive control for caveolin-1 gene expression. The RT-PCR products were separated using 2% agarose gel electrophoresis. Western blot analysis was performed to detect the expression of both clathrin and caveolin-1 proteins in RCECs using mouse mAbs. HeLa cells and A431 epidermoid cells were used as positive controls. The effect of transfection of RCECs (using Lipofectamine 2000TM reagent) with specific antisense oligonucleotides designed against the rabbit clathrin isoform on clathrin protein expression and PLGA nanoparticle uptake was investigated. RESULTS: Apical uptake of nanoparticles in primary cultured RCECs was decreased by 45% and 35%, respectively, as a result of K+ depletion and hypertonic media treatments. Likewise, the same treatments significantly decreased the basolateral uptake of FITC-transferrin by 50%. In contrast, nystatin and filipin had no effect on apical uptake of nanoparticles and cholera toxin B subunit in RCECs, suggesting a lack of the involvement of caveolae in the internalization of these two agents. Confocal microscopy showed fluorescent staining of cell membrane in the presence clathrin mAb, but not in the presence of caveolin-1 mAb, with partial overlap with a nanoparticle staining pattern. RT-PCR confirmed the presence of the clathrin HC gene, but not the caveolin-1 gene, in RCECs as indicated by a 744-bp fragment of the gene. However, caveolin-1 gene was detected in other rabbit tissues such as the epithelium of the cornea and trachea, and heart muscle, as indicated by a 152-bp fragment of the gene. Western blot analysis revealed a clathrin HC band (180 kDa) in RCEC culture and HeLa cells. However, caveolin-1 protein (22 kDa) was not detected in RCEC culture, but was detected in A431 cells. Transfection of RCECs with antisense oligonuceotide directed against clathrin HC resulted in knockdown of the clathrin HC protein in a concentration dependent manner. However, clathrin HC protein knockdown had no effect on apical uptake of nanoparticles in RCECs. CONCLUSIONS: Our findings indicate that endocytosis of nanoparticles in primary cultured RCECs occurs mostly independently of clathrin- and caveolin-1-mediated pathways. In addition, the gene and protein expression of clathrin HC, but not caveolin-1, was identified in rabbit conjunctival epithelial cells.

Animals↗

PubMed2003

Polymer degradation and in vitro release of a model protein from poly(D,L-lactide-co-glycolide) nano- and microparticles.

The objective of the study was to investigate the effect of particle size of nano- and microparticles formulated from poly(D,L-lactide-co-glycolide) (50:50 PLGA) on polymer degradation and protein release. Since the surface area to volume ratio is inversely proportional to the particle size, it is hypothesized that the particle size would influence the polymer degradation as well as the release of the encapsulated protein. PLGA nano- and microparticles of approximate mean diameters of 0.1, 1 and 10 microm, containing bovine serum albumin as a model protein, were formulated using a multiple water-in-oil-in-water emulsion solvent evaporation technique. These particles were incubated at 37 degrees C in phosphate-buffered saline (pH 7.4, 154 mM) and the particles were characterized at various time points for molecular weight of polymer, surface-associated polyvinyl alcohol content (PVA), and the particle surface topology using scanning electron microscopy. The supernatants from the above study were analyzed for the released protein and PVA content. Polymer degradation was found to be biphasic in both nano- and microparticles, with an initial rapid degradation for 20-30 days followed by a slower degradation phase. The 0.1 microm diameter nanoparticles demonstrated relatively higher polymer degradation rate (P<0.05) during the initial phase as compared to the larger size microparticles (first order degradation rate constants of 0.028 day(-1), 0.011 day(-1) and 0.018 day(-1) for 0.1, 1 and 10 microm particles, respectively), however the degradation rates were almost similar (0.008 to 0.009 day(-1)) for all size particles during the later phase. All size particles maintained their structural integrity during the initial degradation phase; however, this was followed by pore formation, deformation and fusion of particles during the slow degradation phase. Protein release from 0.1 and 1 microm particles was greater than that from 10 microm size particles. In conclusion, the polymer degradation rates in vitro were not substantially different for different size particles despite a 10- and 100-fold greater surface area to volume ratio for 0.1 microm size nanoparticles as compared to 1 and 10 microm size microparticles, respectively. Relatively higher amounts of the surface-associated PVA found in the smaller-size nanoparticles (0.1 microm) as compared to the larger-size microparticles could explain some of the observed degradation results with different size particles.

Animals↗

PubMed2003

Fluorescence and electron microscopy probes for cellular and tissue uptake of poly(D,L-lactide-co-glycolide) nanoparticles.

Nanoparticles formulated from poly(D,L-lactide-co-glycolide) (PLGA) and poly(lactide) (PLA) are being extensively investigated for different therapeutic applications such as for sustained drug, vaccine, and gene delivery. For many of these applications, it is necessary to study the intracellular distribution as well as the tissue uptake of nanoparticles to optimize the efficacy of the encapsulated therapeutic agent. Fluorescence and electron microscopic techniques are usually used for the above purposes. Colloidal gold particles and fluorescent polystyrene, which are generally used as model particles for electron and fluorescence microscopy, respectively, may not be suitable alternatives to PLGA/PLA nanoparticles for these studies mainly because of the differences in their physical properties and also because they do not contain any therapeutic agent. The aim of the present study was to develop and characterize PLGA nanoparticle formulations that would be suitable for confocal/fluorescence and transmission electron microscopic (TEM) studies. Towards this objective, PLGA nanoparticles containing 6-coumarin as a fluorescent marker and osmium tetroxide as an electron microscopic marker with bovine serum albumin (BSA) as a model protein were formulated. Different physical properties of marker-loaded nanoparticles such as particle size, zeta potential, residual PVA content and protein-loading were compared with those of unloaded nanoparticles and were found to be not significantly different. Furthermore, marker-loaded nanoparticle formulations were non-toxic to the cells as unloaded nanoparticles. Nanoparticles loaded with 6-coumarin were found to be useful for studying intracellular nanoparticle uptake and distribution using confocal microscopy while osmium tetroxide-loaded nanoparticles were found to be useful for studying nanoparticle uptake and distribution in cells and tissue using TEM. It was concluded that 6-coumarin and osmium tetroxide could serve as useful fluorescence and electron microscopy probes, respectively, for incorporation into nanoparticles to study their cellular and tissue distribution.

Cells, Cultured↗

PubMed2003

Biodegradable nanoparticles for drug and gene delivery to cells and tissue.

Biodegradable nanoparticles formulated from poly (D,L-lactide-co-glycolide) (PLGA) have been extensively investigated for sustained and targeted/localized delivery of different agents including plasmid DNA, proteins and peptides and low molecular weight compounds. Research about the mechanism of intracellular uptake of nanoparticles, their trafficking and sorting into different intracellular compartments, and the mechanism of enhanced therapeutic efficacy of nanoparticle-encapsulated agent at cellular level is more recent and is the primary focus of the review. Recent studies in our laboratory demonstrated rapid escape of PLGA nanoparticles from the endo-lysosomal compartment into cytosol following their uptake. Based on the above mechanism, various potential applications of nanoparticles for delivery of therapeutic agents to the cells and tissue are discussed.

Absorbable Implants↗

PubMed2003

Dynamics of endocytosis and exocytosis of poly(D,L-lactide-co-glycolide) nanoparticles in vascular smooth muscle cells.

PURPOSE: The purpose of this work was to characterize the process of endocytosis, exocytosis, and intracellular retention of poly (D,L-lactide-co-glycolide) nanoparticles in vitro using human arterial vascular smooth muscle cells (VSMCs). METHODS: Nanoparticles containing bovine serum albumin (BSA) as a model protein and 6-coumarin as a fluorescent marker were formulated by a double emulsion-solvent evaporation technique. The endocytosis and exocytosis of nanoparticles in VSMCs were studied using confocal microscopy and their intracellular uptake and retention were determined quantitatively using high-performance liquid chromatography. RESULTS: Cellular uptake of nanoparticles (mean particle size 97 +/- 3 nm) was a concentration-, time-, and energy-dependent endocytic process. Confocal microscopy demonstrated that nanoparticles were internalized rapidly, with nanoparticles seen inside the cells as early as within 1 min after incubation. The nanoparticle uptake increased with incubation time in the presence of nanoparticles in the medium; however, once the extracellular nanoparticle concentration gradient was removed, exocytosis of nanoparticles occurred with about 65% of the internalized fraction undergoing exocytosis in 30 min. Exocytosis of nanoparticles was slower than the exocytosis of a fluid phase marker, Lucifer yellow. Furthermore, the exocytosis of nanoparticles was reduced after the treatment of cells with the combination of sodium azide and deoxyglucose, suggesting that exocytosis of nanopartides is an energy-dependent process. The nanoparticle retention increased with increasing nanoparticle dose in the medium but the effect was relatively less significant with the increase in incubation time. Interestingly, the exocytosis of nanoparticles was almost completely inhibited when the medium was depleted of serum. Further studies suggest that the addition of BSA in the serum free medium with or without platelet derived growth factor (PDGF) induced exocytosis of nanoparticles. The above result suggests that the protein in the medium is either adsorbed onto nanoparticles and/or carried along with nanoparticles inside the cells, which probably interacts with the exocytic pathway and leads to greater exocytosis of nanoparticles. CONCLUSIONS: The study demonstrated that endocytosis and exocytosis of nanoparticles are dynamic and energy-dependent processes. Better understanding of the mechanisms of endocytosis and exocytosis, studies determining the effect of nanoparticle formulation and composition that may affect both the processes, and characterization of intracellular distribution of nanoparticles with surface modifications would be useful in exploring nanoparticles for intracellular delivery of therapeutic agents.

Cell Membrane↗

PubMed2002

Size-dependency of nanoparticle-mediated gene transfection: studies with fractionated nanoparticles.

Nanoparticles formulated from biodegradable polymers such as poly (lactic acid) and poly (D,L-lactide-co-glycolide) (PLGA) are being extensively investigated as non-viral gene delivery systems due to their sustained release characteristics and biocompatibility. PLGA nanoparticles for DNA delivery are mainly formulated using an emulsion-solvent evaporation technique. However, this formulation procedure results in the formation of particles with heterogeneous size distribution. The objective of the present study was to determine the relative transfectivity of the smaller- and the larger-sized fractions of nanoparticles in cell culture. PLGA nanoparticles containing a plasmid DNA encoding luciferase protein as a marker were formulated by a multiple emulsion-solvent evaporation method (mean particle diameter = 97 +/- 3 nm) and were fractionated using a membrane (pore size: 100 nm) filtration technique. The particles that passed through the membrane were designated as the smaller-sized nanoparticles (mean diameter = 70 +/- 2 nm) and the fraction that was retained on the membrane as the larger-sized nanoparticles (mean diameter = 202 +/- 9 nm). The smaller-sized nanoparticles showed a 27-fold higher transfection than the larger-sized nanoparticles in COS-7 cell line and a 4-fold higher transfection in HEK-293 cell line. The surface charge (zeta potential), cellular uptake, and the DNA release were almost similar for the two fractions of nanoparticles, suggesting that some other yet unknown factor(s) is responsible for the observed differences in the transfection levels. The results suggest that the particle size is an important factor, and that the smaller-sized fraction of the nanoparticle formulation predominantly contributes towards their transfection.

Biocompatible Materials↗

PubMed2002

Residual polyvinyl alcohol associated with poly (D,L-lactide-co-glycolide) nanoparticles affects their physical properties and cellular uptake.

Polyvinyl alcohol (PVA) is the most commonly used emulsifier in the formulation of poly lactide and poly (D,L-lactide-co-glycolide) (PLGA) polymeric nanoparticles. A fraction of PVA remains associated with the nanoparticles despite repeated washing because PVA forms an interconnected network with the polymer at the interface. The objective of this study was to determine the parameters that influence the amount of residual PVA associated with PLGA nanoparticles and its effect on the physical properties and cellular uptake of nanoparticles. Nanoparticles were formulated by a multiple emulsion-solvent evaporation technique using bovine serum albumin (BSA) as a model protein. The parameters that affected the amount of residual PVA include the concentration of PVA and the type of organic solvent used in the emulsion. The residual PVA, in turn, influenced different pharmaceutical properties of nanoparticles such as particle size, zeta potential, polydispersity index, surface hydrophobicity, protein loading and also slightly influenced the in vitro release of the encapsulated protein. Importantly, nanoparticles with higher amount of residual PVA had relatively lower cellular uptake despite their smaller particle size. It is proposed that the lower intracellular uptake of nanoparticles with higher amount of residual PVA could be related to the higher hydrophilicity of the nanoparticle surface. In conclusion, the residual PVA associated with nanoparticles is an important formulation parameter that can be used to modulate the pharmaceutical properties of PLGA nanoparticles.

Biocompatible Materials↗