O.S. Odusanya

PLGA-based microparticles loaded with bacterial-synthesized prodigiosin for anticancer drug release: Effects of particle size on drug release kinetics and cell viability

This paper presents the synthesis and physicochemical characterization of biodegradable poly (d,l-lactide-co-glycolide) (PLGA)-based microparticles that are loaded with bacterial-synthesized prodigiosin drug obtained from Serratia marcescens subsp. Marcescens bacteria for controlled anticancer drug delivery. The micron-sized particles were loaded with anticancer drugs [prodigiosin (PG) and paclitaxel (PTX) control] using a single-emulsion solvent evaporation technique. The encapsulation was done in the presence of PLGA (as a polymer matrix) and poly-(vinyl alcohol) (PVA) (as an emulsifier). The effects of processing conditions (on the particle size and morphology) are investigated along with the drug release kinetics and drug-loaded microparticle degradation kinetics. The localization and apoptosis induction by prodigiosin in breast cancer cells is also elucidated along with the reduction in cell viability due to prodigiosin release. The implication of this study is for the potential application of prodigiosin PLGA-loaded microparticles for controlled delivery of cancer drug and treatment to prevent the regrowth or locoregional recurrence, following surgical resection of triple negative breast tumor.

Biosynthesis and the conjugation of magnetite nanoparticles with luteinizing hormone releasing hormone (LHRH).

This paper presents the results of an experimental study of the biosynthesis of magnetite nanoparticles (BMNPs) with particle sizes between 10 nm and 60 nm. The biocompatible magnetic nanoparticles are produced from Magnetospirillum magneticum (M.M.) bacteria that respond to magnetic fields. M.M. bacteria were cultured and used to synthesize magnetite nanoparticles. This was done in an enriched magnetic spirillum growth medium (EMSGM) at different pH levels. The nanoparticle concentrations were characterized with UV-Visible (UV-Vis) spectroscopy, while the particle shapes were elucidated via transmission electron microscopy (TEM). The structure of the particles was studied using X-ray diffraction (XRD), while the hydrodynamic radii, particle size distributions and polydispersity of the nanoparticles were characterized using dynamic light scattering (DLS). Carbodiimide reduction was also used to functionalize the BMNPs with a molecular recognition unit (luteinizing hormone releasing hormone, LHRH) that attaches specifically to receptors that are over-expressed on the surfaces of most breast cancer cell types. The resulting nanoparticles were examined using Fourier Transform Infrared (FTIR) spectroscopy and quantitative image analysis. The implications of the results are then discussed for the potential development of magnetic nanoparticles for the specific targeting and treatment of breast cancer.

Swelling of poly(N-isopropylacrylamide) P(NIPA)-based hydrogels with bacterial-synthesized prodigiosin for localized cancer drug delivery.

We present the results of swelling experiments on poly(N-isopropylacrylamide) P(NIPA)-based hydrogels. The swelling characteristics of P(NIPA)-based homo-polymer and P(NIPA)-based co-polymers with Acrylamide (AM) and Butyl Methacrylate (BMA), were studied using weight gain experiments. The swelling due to the uptake of biosynthesized cancer drug, prodigiosin (PG), was compared to swelling in controlled environments (distilled water (DW), paclitaxel™ (PT) and bromophenol blue (BB)). PG was synthesized with Serratia marcescens (SM) subsp. marcescens bacteria. The mechanisms of drug diffusion and swelling of P(NIPA)-based hydrogels are also elucidated along with characterizing the heterogeneous porous structure of the P(NIPA)-based hydrogels. High Performance Liquefied Chromatography (HPLC) analysis revealed the purity of the biosynthesized prodigiosin to be 92.8%. PG was then absorbed by P(NIPA)-based hydrogels at temperatures between 28-48°C. This is a temperature range that might be encountered during the implantation of biomedical devices for localized cancer treatment via drug delivery and hyperthermia. The results obtained are shown to provide insights for the design of implantable biomedical devices for the localized treatment of breast cancer.

Prodigiosin release from an implantable biomedical device: kinetics of localized cancer drug release.

This paper presents an implantable encapsulated structure that can deliver localized heating (hyperthermia) and controlled concentrations of prodigiosin (a cancer drug) synthesized by bacteria (Serratia marcesce (subsp. marcescens)). Prototypical Poly-di-methyl-siloxane (PDMS) packages, containing well-controlled micro-channels and drug storage compartments, were fabricated along with a drug-storing polymer produced by free radical polymerization of Poly(N-isopropylacrylamide)(PNIPA) co-monomers of Acrylamide (AM) and Butyl-methacrylate (BMA). The mechanisms of drug diffusion of PNIPA-base gels were elucidated. Scanning Electron Microscopy (SEM) was also used to study the heterogeneous porous structure of the PNIPA-based gels. The release exponents, n, of the gels were found to between 0.5 and 0.7. This is in the range expected for Fickian (n=0.5). Deviation from Fickian diffusion was also observed (n>0.5) diffusion. The gel diffusion coefficients were shown to vary between 2.1×10(-12)m(2)/s and 4.8×10(-6)m(2)/s. The implications of the results are then discussed for the localized treatment of cancer via hyperthermia and the controlled delivery of prodigiosin from encapsulated PNIPA-based devices.

Gold nanoparticles for cancer detection and treatment: The role of adhesion

This paper presents the results of an experimental study of the effects of adhesion between gold nanoparticles and surfaces that are relevant to the potential applications in cancer detection and treatment. Adhesion is measured using a dip coating/atomic force microscopy (DC/AFM) technique. The adhesion forces are obtained for dip-coated gold nanoparticles that interact with peptide or antibody-based molecular recognition units (MRUs) that attach specifically to breast cancer cells. They include MRUs that attach specifically to receptors on breast cancer cells. Adhesion forces between anti-cancer drugs such as paclitaxel, and the constituents of MRU-conjugated Au nanoparticle clusters, are measured using force microscopy techniques. The implications of the results are then discussed for the design of robust gold nanoparticle clusters and for potential applications in localized drug delivery and hyperthermia.

Extraction and encapsulation of prodigiosin in chitosan microspheres for targeted drug delivery

The encapsulation of drugs in polymeric materials has brought opportunities to the targeted delivery of chemotherapeutic agents. These polymeric delivery systems are capable of maximizing the therapeutic activity, as well as reducing the side effects of anti-cancer agents. Prodigiosin, a secondary metabolite extracted from the bacteria, Serratia marcescens, exhibits anti-cancer properties. Prodigiosin-loaded chitosan microspheres were prepared via water-in-oil (w/o) emulsion technique, using glutaraldehyde as a cross-linker. The morphologies of the microspheres were studied using scanning electron microscopy. The average sizes of the microspheres were between 40μm and 60μm, while the percentage yields ranged from 42±2% to 55.5±3%. The resulting encapsulation efficiencies were between 66.7±3% and 90±4%. The in-vitro drug release from the microspheres was characterized by zeroth order, first order and Higuchi and Korsmeyer-Peppas models.

Statistical Distributions of the Strength and Fracture Toughness of Recycled Polyethylene-Reinforced Laterite Composites

AbstractThis paper presents the results of combined experimental and theoretical studies of the statistical distributions of the strength and fracture toughness of recycled polyethylene-reinforced laterite composites for potential applications in building materials. The composites are produced with different volume percentages (0–30% v/v) and particle sizes (∼300±0.02, ∼600 ± 0.03, ∼900 ± 0.03, ∼1,200±0.02, ∼1,500±0.04, and 1,800±0.03  μm) of powdered polyethylene (PE) in a laterite matrix. The composites with ∼900±0.03  μm and 20-volume percentage of PE are shown to have the best combination of flexural-compressive strengths and fracture toughness. The statistical variations in the flexural-compressive strengths and fracture toughness are well characterized by the Weibull distributions.

Adhesion of ligand-conjugated biosynthesized magnetite nanoparticles to triple negative breast cancer cells

This paper presents the results of an experimental study of the adhesion forces between components of model conjugated magnetite nanoparticle systems for improved selectivity in the specific targeting of triple negative breast cancer. Adhesion forces between chemically synthesized magnetite nanoparticles (CMNPs), biosynthesized magnetite nanoparticles (BMNPs), as well as their conjugated systems and triple negative breast cancer cells (MDA-MB-231) or normal breast cells (MCF 10A) are elucidated at a nanoscale. In all cases, the BMNPs had higher adhesion forces (to breast cancer cells and normal breast cells) than CMNPs. The adhesion of LHRH-conjugated BMNPs or BSA-conjugated BMNPs to cancer cells is shown to be about 6 times to that of normal breast cells. The increase in adhesion forces between luteinizing hormone-releasing hormone, LHRH- or EphA2, a breast specific antibody(BSA)-conjugated BMNPs to breast cancer cells is attributed to van der Waals interactions between the peptides/antibodies from the conjugated nanoparticles and the over-expressed receptors (revealed using immunofluorescence staining) on the surfaces of the breast cancer. The implications of the results are discussed for the selectivity and specificity of breast cancer targeting by ligand-conjugated BMNPs.

A comparative study of the adhesion of biosynthesized gold and conjugated gold/prodigiosin nanoparticles to triple negative breast cancer cells

This paper explores the adhesion of biosynthesized gold nanoparticles (AuNPs) and gold (Au) nanoparticle/prodigiosin (PG) drug nanoparticles to breast cancer cells (MDA-MB-231 cells). The AuNPs were synthesized in a record time (less than 30 s) from Nauclea latifolia leaf extracts, while the PG was produced via bacterial synthesis with Serratia marcescens sp. The size distributions and shapes of the resulting AuNPs were characterized using transmission electron microscopy (TEM), while the resulting hydrodynamic diameters and polydispersity indices were studied using dynamic light scattering (DLS). Atomic Force Microscopy (AFM) was used to study the adhesion between the synthesized gold nanoparticles (AuNPs)/LHRH-conjugated AuNPs and triple negative breast cancer cells (MDA-MB-231 cells), as well as the adhesion between LHRH-conjugated AuNP/PG drug and MDA-MB-231 breast cancer cells. The adhesion forces between LHRH-conjugated AuNPs and breast cancer cells are shown to be five times greater than those between AuNPs and normal breast cells. The increase in adhesion is shown to be due to the over-expression of LHRH receptors on the surfaces of MDA-MB-231 breast cancer cells, which was revealed by confocal immuno-fluorescence microscopy. The implications of the results are then discussed for the selective and specific targeting and treatment of triple negative breast cancer.

Extended pulsated drug release from PLGA-based minirods

The kinetics of degradation and sustained cancer drugs (paclitaxel (PT) and prodigiosin (PG)) release are presented for minirods (each with diameter of ~5 and ~6 mm thick). Drug release and degradation mechanisms were studied from solvent-casted cancer drug-based minirods under in vitro conditions in phosphate buffer solution (PBS) at a pH of 7.4. The immersed minirods were mechanically agitated at 60 revolutions per minute (rpm) under incubation at 37 °C throughout the period of the study. The kinetics of drug release was studied using ultraviolet visible spectrometry (UV-Vis). This was used to determine the amount of drug released at 535 nm for poly(lactic-co-glycolic acid) loaded with prodigiosin (PLGA-PG) samples, and at 210 nm, for paclitaxel-loaded samples (PLGA-PT). The degradation characteristics of PLGA-PG and PLGA-PT are elucidated using optical microscope as well as scanning electron microscope (SEM). Statistical analysis of drug release and degradation mechanisms of PLGA-based minirods were performed. The implications of the results are discussed for potential applications in implantable/degradable structures for multi-pulse cancer drug delivery.