Effect of Particle Size of Nanospheres and Microspheres on the Cellular-Association and Cytotoxicity of Paclitaxel in 4T1 Cells

Cellulose Nanofiber-Coated Perfluoropentane Droplets: Fabrication and Biocompatibility Study

Purpose

To study the effect of cellulose nanofiber (CNF)-shelled perfluoropentane (PFP) droplets on the cell viability of 4T1 breast cancer cells with or without the addition of non-encapsulated paclitaxel.

Methods

The CNF-shelled PFP droplets were produced by mixing a CNF suspension and PFP using a homogenizer. The volume size distribution and concentration of CNF-shelled PFP droplets were estimated from images taken with an optical microscope and analyzed using Fiji software and an in-house Matlab script. The thermal stability was qualitatively assessed by comparing the size distribution and concentration of CNF-shelled PFP droplets at room temperature (~22°) and 37°C. The cell viability of 4T1 cells was measured using a 3-[4,5-dimethylthiazol-2yl]-2,5-diphenyltetrazolium bromide (MTT) assay. Additionally, a hemolysis assay was performed to assess blood compatibility of CNF-shelled PFP droplets.

Results

The droplet diameter and concentration of CNF-shelled PFP droplets decreased after 48 hours at both room temperature and 37°C. In addition, the decrease in concentration was more significant at 37°C, from 3.50 ± 0.64×10⁶ droplets/mL to 1.94 ± 0.10×10⁶ droplets/mL, than at room temperature, from 3.65 ± 0.29×10⁶ droplets/mL to 2.56 ± 0.22×10⁶ droplets/mL. The 4T1 cell viability decreased with increased exposure time and concentration of paclitaxel, but it was not affected by the presence of CNF-shelled PFP droplets. No hemolysis was observed at any concentration of CNF-shelled PFP droplets.

Conclusion

CNF-shelled PFP droplets have the potential to be applied as drug carriers in ultrasound-mediated therapy.

Tolerability to non-endosomal, micron-scale cell penetration probed with magnetic particles

The capability of HeLa cells to internalize large spherical microparticles has been evaluated by using inorganic, magnetic microparticles of 1 and 2.8 µm of diameter. In both absence but especially under the action of a magnet, both types of particles were uptaken, in absence of cytotoxicity, by a significant percentage of cells, in a non-endosomal process clearly favored by the magnetic field. The engulfed particles efficiently drive inside the cells chemically associated proteins such as GFP and human alpha-galactosidase A, without any apparent loss of protein functionalities. While 1 µm particles are completely engulfed, at least a fraction of 2.8 µm particles remain embedded into the cell membrane, with only a fraction of their surface in cytoplasmic contact. The detected tolerance to endosomal-independent cell penetration of microscale objects is not then restricted to organic, soft materials (such as bacterial inclusion bodies) as previously described, but it is a more general phenomenon also applicable to inorganic materials. In this scenario, the use of magnetic particles in combination with external magnetic fields can represent a significant improvement in the internalization efficiency of such agents optimized as drug carriers. This fact offers a wide potential in the design and engineering of novel particulate vehicles for therapeutic, diagnostic and theragnostic applications.

Formulation, Characterisation and In vitro Cytotoxic Effect of Lens culinaris Medikus Seeds Extract Loaded Chitosan Microspheres

OBJECTIVE

The aim of present study was to formulate chitosan microspheres loaded with ethanolic extract of Lens culinaris Medikus (L.culinaris) seeds (ME) and to explore its anticancer potential against lung cancer (A549) cell line.

METHODS

Central composite design was applied to prepare and optimise the chitosan microspheres. The prepared microspheres were evaluated for its physicochemical characterisation, in vitro drug release and anti-cancer potential in vitro.

RESULTS

L.culinaris loaded chitosan microspheres were prepared successfully with suitable particle size, entrapment efficiency and drug release. The developed ME were spherical shaped with the particle size of 2.08 μm. The drug entrapment efficiency and cumulative drug release was found 1.58±0.02% and 81.95±0.35%, respectively. Differential scanning calorimetry studies revealed no interaction between drugs and polymers used. The cytotoxic effect of the optimised formulation revealed a significant response as compared to the ethanolic extract of L.culinaris seeds (IC₅₀: 22.56 μg/ml vs. 63.58 μg/ml), which was comparable to that of reference drug, doxorubicin (22 μg/ml). These observations demonstrate that the optimised microspheres are effective against lung cancer (A549) cells.

CONCLUSION

The significant cytotoxic response of the developed microspheres may be attributed due to its low particle size, high entrapment efficiency and prolonged drug release profile.

Opportunities and challenges of fatty acid conjugated therapeutics

Instability, poor cellular uptake and unfavorable pharmacokinetics and biodistribution of many therapeutic molecules require modification in their physicochemical properties. The conjugation of these APIs with fatty acids has demonstrated an enhancement in their lipophilicity and stability. The improvement in the formulations that resulted from the conjugation of a drug with a fatty acid includes increased half-life, enhanced cellular uptake and retention, targeted tumor delivery, reduced chemoresistance in cancer, and improved blood-brain-barrier (BBB) penetration. In this review, various therapeutic molecules, including small molecules, peptides and oligonucleotides, that have been conjugated with fatty acid have been thoroughly discussed along with various conjugation strategies. The application of nano-system based delivery is gaining a lot of attention due to its ability to provide controlled drug release, targeting and reducing the extent of side effects. This review also covers various nano-carriers that have been utilized for the delivery of fatty acid drug conjugates. The enhanced lipophilicity of the drug-fatty acid conjugate has shown to enhance the affinity of the drug towards these carriers, thereby increasing the entrapment efficiency and formulation performance.

Toxicological Concerns of Engineered Nanosize Drug Delivery Systems

Matters when converted into nanosize provide some unique surface properties, which are different from those of the bulk materials. Nanomaterials show some extraordinary behavioral patterns because of those properties, such as supermagnetism, quantum confinement, etc. A great deal of implication of nanomaterials in nanomedicine has already been realized. Utility of nanomaterials as drug nanocarrier projects many potential advantages of them in drug delivery. Despite many such advantages, the potential risk of health and environmental hazards related to them cannot be ignored. Here various physicochemical factors, such as chemical nature, degradability, surface properties, surface charge, particle size, and shape, have been shown to play a crucial role in toxicity related to drug nanocarriers. Evidence-based findings of some drug nanocarriers have been incorporated to provide distinct knowledge to the readers in the field. A glimpse of current regulatory controls and measures required to combat the challenges of toxicological aspects of drug nanocarriers have been described.

Differences in physicochemical properties to consider in the design, evaluation and choice between microparticles and nanoparticles for drug delivery

INTRODUCTION

The increase in the development of novel nanoparticle drug delivery systems makes the choice between micro- and nanoscale drug delivery systems ubiquitous. Changes in physical and chemical properties between micro- to nanosized particles give them different properties that influence their physiological, anatomical and clinical behavior and therefore potential application.

AREAS COVERED

This review focuses on the effect changes in the surface-to-volume ratio have on the thermal properties, solubility, dissolution and crystallization of micro- versus nanosized drug delivery systems. With these changes in the physicochemical properties in mind, the review covers computational and biophysical approaches to the design and evaluation of micro- and nanodelivery systems. The emphasis of the review is on the effect these properties have on clinical performance in terms of drug release, tissue retention, biodistribution, efficacy, toxicity and therefore choice of delivery system.

EXPERT OPINION

Ultimately, the choice between micro- and nanometer-sized delivery systems is not straightforward. However, if the fundamental differences in physical and chemical properties are considered, it can be much easier to make a rational choice of the appropriate drug delivery system size.

The behavior of lipid debris left on cell surfaces from microbubble based ultrasound molecular imaging

Lipid monolayer coated microbubbles are currently being developed to identify vascular regions that express certain surface proteins as part of the new technique of ultrasound molecular imaging. The microbubbles are functionalized with targeting ligands which bind to the desired cells holding the microbubbles in place as the remaining unbound microbubbles are eliminated from circulation. Subsequent scanning with ultrasound can detect the highly reflectant microbubbles that are left behind. The ultrasound scanning and detection process results in the destruction of the microbubble, creating lipid fragments from the monolayer. Here we demonstrate that microbubbles targeted to 4T1 murine breast cancer cells and human umbilical cord endothelial cells leave behind adhered fragments of the lipid monolayer after exposure to ultrasound with peak negative pressures of 0.18 and 0.8MPa. Most of the observed fragments were large enough to be resistant to receptor mediated endocytosis. The fragments were not observed to incorporate into the lipid membrane of the cell over a period of 96min. They were not observed to break into smaller pieces or significantly change shape but they were observed to undergo translation and rotation across the cell surface as the cells migrated over the substrate. These large fragments will apparently remain on the surface of the targeted cells for significant periods of time and need to be considered for their potential effects on blood flow through the microcapillaries and potential for immune system recognition.

Nanosolvated microtubule-modulating chemotherapeutics: a case-to-case study

About 10% of the drugs in the preclinical stage are poorly soluble, 40% of the drugs in the pipeline have poor solubility, and even 60% of drugs coming directly from synthesis have aqueous solubility below 0.1 mg/ml. Out of the research around, 40% of lipophilic drug candidates fail to reach the market despite having potential pharmacodynamic activities. Microtubule-modulating chemotherapeutics is an important class of cancer chemotherapy. Most chemotherapeutics that belong to this category are plant-derived active constituents, such as vincristine, vinblastine, colchicine, docetaxel, paclitaxel, and noscapinoids. The pKa of a drug considerably affects its solubility in physiological fluids and consequently bioavailability. It usually ranges from 5 to 12 for microtubule-modulating drugs. Hence, the solubility of these drugs in physiological fluids is considerably affected by a change in pH. However, because of unpredictable parameters involved in poor solubility and the low oral bioavailability of these chemotherapeutics during the early phases of drug development, they often have an unusual pharmacokinetic profile. This makes the development process of novel chemotherapeutics slow, inefficient, patient-unfriendly, and very costly, emphasizing a need for more rational approaches on the basis of preclinical concepts. Nanosolvation is a process of increasing the polarity of a hydrophobic molecule either by solvation or cavitization in a hydrophilic macrocycle. The present review therefore focuses on the techniques applied in nanosolvation of microtubule-modulating chemotherapeutics to enhance solubility and bioavailability. The methodologies described will be highly beneficial for anticancer researchers to follow a trend of rational drug development.

Aptamer-labeled PLGA nanoparticles for targeting cancer cells

Cancer is one of the leading causes of death in most parts of the world and is a very serious cause of concern particularly in developing countries. In this work, we prepared and evaluated the aptamer-labeled paclitaxel-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (Apt-PTX-PLGA NPs) which can ameliorate drug bioavailability and enable accurate drug targeting to cancer cells with controlled drug release for cancer therapy. Paclitaxel-loaded PLGA nanoparticles (PTX-PLGA NPs) were formulated by a single-emulsion/solvent evaporation method and were further surface-functionalized with a chemical cross-linker bis(sulfosuccinimidyl) suberate (BS3) to enable binding of aptamer on to the surface of the nanoparticles. The prepared nanoparticles were characterized by atomic force microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. Cytotoxicity studies were carried out using normal human mammary epithelial cells (HMEC cells) and human glial cancer cells (GI-1 cells) by methylthiazolyldiphenyl-tetrazolium bromide assay and Alamar blue assay, which confirmed that PTX-PLGA NPs with aptamer conjugation (Apt-PTX-PLGA NPs) were comparatively non-toxic to HMEC cells while toxic to GI-1 cancer cells. Cellular uptake of PTX-PLGA NPs with and without aptamer conjugation was studied using GI-1 cells and monitored by confocal microscopy and phase contrast microscopy. Our studies demonstrated significant internalization and retention of nanoparticles inside the cells, inducing apoptosis. The preferential accumulation of PTX-PLGA NPs within the cancer cells were also confirmed by flow cytometry-based uptake studies. The results indicated that Apt-PTX-PLGA NPs could be a promising targeted therapeutic delivery vehicle for cancer treatment.

Enhanced cellular association of paclitaxel delivered in chitosan-PLGA particles

We have previously demonstrated that the cellular association, cytotoxicity, and in vivo anti-tumor efficacy of paclitaxel are significantly greater when delivered in PLGA microparticles compared to nanoparticles. The purpose of this research is to test the hypothesis that mucoadhesive chitosan promotes adhesion of PLGA particles to mucus on the tumor epithelium, resulting in enhanced cellular association and cytotoxicity of paclitaxel. PLGA particles containing paclitaxel or Bodipy(®) were prepared and chitosan was either adsorbed or chemically conjugated to the particle surface. The cellular association and cytotoxicity of paclitaxel in 4T1 cells was determined. A 4-10 fold increase in cellular association of paclitaxel was observed when chitosan was adsorbed or conjugated to the PLGA particles. Chitosan-conjugated PLGA microparticles were most cytotoxic with an IC(50) value of 0.77 μM. Confocal microscopy demonstrated that chitosan-PLGA microparticles adhered to the surface of 4T1 cells. Pretreatment of either 4T1 cells or chitosan-PLGA particles with mucin resulted in significant increase in cellular association of paclitaxel. A linear correlation was established between theoretical amount of chitosan used and experimentally determined amount of chitosan adsorbed or conjugated to PLGA nanoparticles. In conclusion, cellular association and cytotoxicity of paclitaxel was significantly enhanced when delivered in chitosan-PLGA particles.

Block copolymer micelles as delivery vehicles of hydrophobic drugs: Micelle–cell interactions

One-third of drugs in development are water insoluble and one-half fail in trials because of poor pharmacokinetics. Block copolymer micelles are nanosized particles that can solubilize hydrophobic drugs and alter their kinetics in vitro and in vivo. However, block copolymer micelles are not solely passive drug containers that simply solubilize hydrophobic drugs; cells internalize micelles. To facilitate the development of advanced, controlled, micellar drug delivery vehicles, we have to understand the fate of micelles and micelle-incorporated drugs in cells and in vivo. With micelle-based drug formulations recently reaching clinical trials, the impetus for answers is ever so strong and detailed studies of interactions of micelles and cells are starting to emerge. Most notably, the question arises: Is the internalization of block copolymer micelles carrying small molecular weight drugs an undesired side effect or a useful means of improving the effectiveness of the incorporated drugs?

Direct plasmid DNA encapsulation within PLGA nanospheres by single oil-in-water emulsion method

Plasmid DNA was encapsulated within poly(d,l-lactic-co-glycolic acid) (PLGA) nanospheres by using polyethylene glycol (PEG) assisted solubilization technique of plasmid DNA in organic solvents. Plasmid DNA was solubilized in an organic solvent mixture composed of 80% methylene chloride and 20% DMSO by producing PEG/DNA nano-complexes having an average diameter less than 100 nm. DNA could be solubilized in the organic solvent mixture to a greater extent with increasing the weight ratio of PEG/DNA. PLGA nanospheres encapsulating DNA were successfully prepared by the single O/W emulsion method. They exhibited greater loading efficiency and better structural integrity, compared to those prepared by the W/O/W double emulsion method. Plasmid DNA could be successfully delivered to macrophage cells to express an exogenous gene. This new formulation enabled high loading of intact plasmid DNA within PLGA nanospheres useful for DNA vaccines.

Influence of size, surface, cell line, and kinetic properties on the specific binding of A33 antigen-targeted multilayered particles and capsules to colorectal cancer cells

There has been increased interest in the use of polymer capsules formed by the layer-by-layer (LbL) technique as therapeutic carriers to cancer cells due to their versatility and ease of surface modification. We have investigated the influence of size, surface properties, cell line, and kinetic parameters such as dosage (particle concentration) and incubation time on the specific binding of humanized A33 monoclonal antibody (huA33 mAb)-coated LbL particles and capsules to colorectal cancer cells. HuA33 mAb binds to the A33 antigen present on almost all colorectal cancer cells and has demonstrated great promise in clinical trials as an immunotherapeutic agent for cancer therapy. Flow cytometry experiments showed the cell binding specificity of huA33 mAb-coated particles to be size-dependent, with the optimal size for enhanced selectivity at approximately 500 nm. The specific binding was improved by increasing the dosage of particles incubated with the cells. The level of specific versus nonspecific binding was compared for particles terminated with various polyelectrolytes to examine the surface dependency of antibody attachment and subsequent cell binding ability. The specific binding of huA33 mAb-coated particles is also reported for two colorectal cancer cell lines, with an enhanced binding ratio between 4 and 10 obtained for the huA33 mAb-functionalized particles. This investigation aims to improve the level of specific targeting of LbL particles, which is important in targeted drug and gene delivery applications.

Cytotoxic evaluation of cubic boron nitride in human origin cultured cells

The aim of this study was to evaluate the cytotoxicity of cubic boron nitride (cBN), a component of surgical cutting tools. The small quantities of cBN that typically remain on implants as a result of the manufacturing process may act as abrasives, injuring tissues surrounding the implant. To determine how cBN affects cells, we treated human neuroblastoma cells (NB-1) and human articular chondrocytes (nHAC-kn) with different concentrations of cBN powder and assessed cell growth and cell survival using the methyl-thiazol-tetrazolium (MTT) assay and a fluorescence probe assay. We also assessed the effects of tungsten carbide (WC) and cobalt (Co), two common components of joint implants, on cell growth and cell survival. Both cBN and WC moderately inhibited NB-1 and nHAC-kn cell growth. However, cBN and WC did not affect cell survival, even at high concentrations (40 microg/ml). By contrast, Co affected cell survival, inducing cell death in both cell types at increasing concentrations. These results suggest that cBN may be less toxic than WC alloys containing Co.