Polymer nanoparticles: Preparation techniques and size-control parameters

Polymer nanoparticles for drug and small silencing RNA delivery to treat cancers of different phenotypes

Advances in nanotechnology have provided powerful and efficient tools in the development of cancer diagnosis and therapy. There are numerous nanocarriers that are currently approved for clinical use in cancer therapy. In recent years, biodegradable polymer nanoparticles have attracted a considerable attention for their ability to function as a possible carrier for target-specific delivery of various drugs, genes, proteins, peptides, vaccines, and other biomolecules in humans without much toxicity. This review will specifically focus on the recent advances in polymer-based nanocarriers for various drugs and small silencing RNA's loading and delivery to treat different types of cancer.

Surfactant-free polymeric nanoparticles composed of PEG, cholic acid and a sucrose moiety

New amphiphilic polymers synthesized from a sucrose-containing conjugate exhibited interesting self-assembly properties in water. Owing to their amphiphilic characteristics polymeric nanoparticles were prepared by a nanoprecipitation method without any surfactants. These nanoparticles formulated with biocompatible building blocks can be considered a potential candidate for drug delivery applications.

Shear flow controlled morphological polydispersity of amphiphilic ABA triblock copolymer vesicles

Self-assembled polymeric aggregates are generally polydisperse in morphology due to the existence of many metastable states in the system. This shortcoming becomes a bottleneck for preparing high quality self-assembled polymeric materials. An important concern is the possibility of controlling morphological polydispersity through the modulation of the metastable states. In this study, both simulative and experimental results show that the metastable states can be modulated. As a typical example, the morphological polydispersity of amphiphilic ABA triblock copolymer vesicles have been successfully controlled by shear flow. A higher shear rate results in more uniform and smaller vesicles. However, if the shear rate is extremely high, small spheres and short rods can be observed. These findings not only give a deeper insight into the metastable behavior of self-assembled polymeric aggregates but also provide a new strategy for improving the uniformity of vesicles.

Nanooncology: the future of cancer diagnosis and therapy

In recent years, there has been an unprecedented expansion in the field of nanomedicine with the development of new nanoparticles for the diagnosis and treatment of cancer. Nanoparticles have unique biological properties given their small size and large surface area-to-volume ratio, which allows them to bind, absorb, and carry compounds such as small molecule drugs, DNA, RNA, proteins, and probes with high efficiency. Their tunable size, shape, and surface characteristics also enable them to have high stability, high carrier capacity, the ability to incorporate both hydrophilic and hydrophobic substances and compatibility with different administration routes, thereby making them highly attractive in many aspects of oncology. This review article will discuss how nanoparticles are able to function as carriers for chemotherapeutic drugs to increase their therapeutic index; how they can function as therapeutic agents in photodynamic, gene, and thermal therapy; and how nanoparticles can be used as molecular imaging agents to detect and monitor cancer progression.

Particle formation in the emulsion-solvent evaporation process

The mechanism of particle formation from submicrometer emulsion droplets by solvent evaporation is revisited. A combination of dynamic light scattering, fluorescence resonance energy transfer, zeta potential measurements, and fluorescence cross-correlation spectroscopy is used to analyze the colloids during the evaporation process. It is shown that a combination of different methods yields reliable and quantitative data for describing the fate of the droplets during the process. The results indicate that coalescence plays a minor role during the process; the relatively large size distribution of the obtained polymer colloids can be explained by the droplet distribution after their formation.

Dual sustained release delivery system for multiple route therapy of an antiviral drug

CONTEXT

The first successful molecule against herpes infections was Acyclovir, which competes with new generations in the market, with its potential activity. The major physicochemical constraints and pharmacokinetics of Acyclovir such as low solubility, poor permeability, less half-life, high dose has initiated many researchers to develop diverse modified release dosage forms.

OBJECTIVE

The objective of this work was to design polymeric nanoparticles of Acyclovir and then incorporate the drug-loaded nanoparticles within an in situ gelling system to provide dual sustained release effect, whereby the duration of action and bioavailability through different routes of administration could be improved.

MATERIALS AND METHODS

The formulation was designed through 3(2) factorial design, first developing the nanoparticles using Polycaprolactone and Pluronic F127 by Solvent evaporation process, followed by dispersion of the suspended nanoparticles into thermosensitive in situ gelling system of Pluronic F127 with Carbopol.

RESULTS AND DISCUSSION

The characterization of the nanoparticles and its sol-gel system performed through zeta sizer, SEM, XRD, TG-DSC, FTIR and rheology helped to optimize the formulation. The drug release could be sustained to 60% and 30% at eight hours, for the nanoparticles and their in situ gel systems, respectively, with non-Fickian diffusion mechanism of drug release. The test for % cell viability with NIH3T3 cell line revealed low level of toxicity for the nanoparticles.

CONCLUSION

The statistical significance obtained for the trail formulations experimentally proved its suitability for this dosage form design to achieve desired level of drug release.

Availability of polymeric nanoparticles for specific enhanced and targeted drug delivery

Over the past 20–30 years there has been quite a number of studies interested in polymeric nanoparticle (PNP) systems as a pharmaceutical approach for poorly soluble drugs, peptide drugs, gene and antibodies. Now, the products based on the PNP technologies are used in the fields of medical science, pharmaceutical science, tissue engineering and clothing, food and housing. This review focuses attention on PNPs for specific enhanced and targeted drug delivery of therapeutic drugs including peptide drugs as well as drug delivery applications of such systems. Outcomes from recent studies on polymers, how to make PNPs, pharmacokinetics and pharmacodynamics of PNPs, and the release profiles from PNPs and related systems are also described, including their pharmacokinetics and pharmacodynamics, if available. In addition, the latest PNP trends and will be described.

Preparation of pH-responsive polymer core-shell nanospheres for delivery of hydrophobic antineoplastic drug ellipticine

Antineoplastic drug ellipticine and its derivatives are used in human cancer therapy. However, their clinical applications have been limited by its great hydrophobicity and severe side effects. An efficient delivery system is therefore very desirable. In this research, an ellipticine-loaded core-shell structured nanosphere namely poly(DEAEMA)-poly(PEGMA) is designed as a drug carrier and prepared via a two-step semibatch emulsion polymerization method where DEAEMA and PEGMA represent 2-(diethylamino)ethyl methacrylate and poly(ethylene glycol) methacrylate, respectively. The in-vitro release profiles of ellipticine towards the different pH liposome vesicles are recorded as a function of time at 37 °C. It is found that release of ellipticine from the core-shell polymer matrix is a pH-responsive and controlled release process. The three pH's of 3, 4, and 5 trigger a significant ellipticine release of 88% after 98 h, 83% after 98 h, and 79% after 122 h, respectively. The release mechanism of ellipticine from the core-shell polymer matrix under acidic conditions is explored. The synthesis and encapsulation process developed herein provides a new perspective for the development of appropriate delivery systems to deliver the ellipticine and its analogues, as well as other types of hydrophobic drugs to a given target cell or tumor tissue.

Polymer encapsulation of inorganic nanoparticles for biomedical applications

Hybrid inorganic colloidal particles have attracted a great attention in the last years, and they have been largely used in various applications and more particularly in biomedical nanotechnology. Recently, they are used as carriers for biomolecules, and exploited for use in microsystems, microfluidics and in lab-on-a chip based bionanotechnology. Various kinds of hybrid particles can be listed starting from classical inorganic nanoparticles such as silica, gold, silver, iron oxide and those exhibiting intrinsic properties such as semiconducting nanoparticles (e.g. quantum dots). As a general tendency, to be conveniently used in biomedical applications, the encapsulation of the inorganic nanoparticles in a polymer matrix is incontestably needed. Consequently, various chemistry-based encapsulation processes have been developed and showed promising results as compared to the encapsulation using preformed polymers.

Paclitaxel-loaded PCL-TPGS nanoparticles: in vitro and in vivo performance compared with Abraxane®

The purpose of this work was to develop Cremophor(®) EL-free nanoparticles (NPs) loaded with Paclitaxel (PTX) in order to improve the drug i.v. pharmacokinetic profile and to evaluate its activity against commercially available formulations such as Taxol(®) and Abraxane(®). PTX-loaded poly(ε-caprolactone)-alpha tocopheryl polyethylene glycol 1000 succinate (PCL-TPGS) NPs were prepared using three different techniques: (i) by nanoprecipitation (NPr-method), (ii) by emulsion-solvent evaporation homogenized with an Ultra-Turrax(®) (UT-method) and (iii) by emulsion-solvent evaporation homogenized with an ultrasonicator (US-method). The NPs prepared by US-method showed the smallest size and the highest drug content. The NPs exhibited a slow and continuous release of PTX. The in vitro anti-tumoral activity was assessed using two human breast cancer cell lines (MCF-7 and MDA-MB-231) with the WTS assay. Cytotoxicity studies with both cell lines showed that PTX-loaded PCL-TPGS NPs exhibited better anti-cancer activity compared to PTX solution and the commercial formulation Abraxane(®) at different concentrations. Importantly, in the case of triple negative MDA-MB-231 breast cancer cells, the IC50 value for PTX-loaded PCL-TPGS NPs was 7.8 times lower than Abraxane(®). Finally, in vivo studies demonstrated that PTX-loaded PCL-TPGS NPs exhibited longer systemic circulation time and slower plasma elimination rate than Taxol(®) and Abraxane(®). Therefore, the novel NPs investigated might be an alternative nanotechnological platform for PTX delivery system in cancer chemotherapy.

A novel drug "copper acetylacetonate" loaded in folic acid-tagged chitosan nanoparticle for efficient cancer cell targeting

Several copper compounds have proven anti-cancer activity. Similarly, curcumin a derivative of 1,3 diketone, which is not plenty in nature, has comparable anti-cancer activity. In this work, we have explored the synergistic anti-cancer activity of copper ion and acetylacetone complex containing 1,3 diketone group. The cytotoxicity of the copper acetylacetonate (CuAA) complex was evaluated on various cancer cells and LD50 doses were determined. To investigate the mechanism, various biochemical assays were performed and reactive oxygen species as well as the glutathione level in the cell were found to be increased after the treatment with the above-mentioned complex. Further this reagent induced apoptosis and reduced mitochondrial membrane potential of the cells. Because of the poor solubility and reasonable cytotoxicity of CuAA, polymer nanoparticles (NPs) of chitosan derivatives were used for delivery in cancer cells. For the targeted delivery, folic acid-tagged hydrophobic-modified chitosan NPs were developed and the CuAA was encapsulated. Finally, these drug-encapsulated NPs were successfully delivered to folate receptor over-expressed cancer cells. Thus using nanotechnology, we developed an anti-cancer agent suitable for targeted delivery.

A comparative in vitro evaluation of self-assembled PTX-PLA and PTX-MPEG-PLA nanoparticles

We present a dialysis technique to direct the self-assembly of paclitaxel (PTX)-loaded nanoparticles (NPs) using methoxypolyethylene glycol-poly(d,l-lactide) (MPEG-PLA) and PLA, respectively. The composition, morphology, particle size and zeta potential, drug loading content, and drug encapsulation efficiency of both PTX-PLA NPs and PTX-MPEG-PLA NPs were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, dynamic light scattering, electrophoretic light scattering, and high-performance liquid chromatography. The passive targeting effect and in vitro cell viability of the PTX-MPEG-PLA NPs on HeLa cells were demonstrated by comparative cellular uptake and MTT assay of the PTX-PLA NPs. The results showed that the PTX-MPEG-PLA NPs and PTX-PLA NPs presented a hydrodynamic particle size of 179.5 and 441.9 nm, with a polydispersity index of 0.172 and 0.189, a zeta potential of -24.3 and -42.0 mV, drug encapsulation efficiency of 18.3% and 20.0%, and drug-loaded content of 1.83% and 2.00%, respectively. The PTX-MPEG-PLA NPs presented faster release rate with minor initial burst compared to the PTX-PLA NPs. The PTX-MPEG-PLA NPs presented superior cell cytotoxicity and excellent cellular uptake compared to the PTX-PLA NPs. These results suggested that the PTX-MPEG-PLA NPs presented more desirable characteristics for sustained drug delivery compared to PTX-PLA NPs.

Rapamycin-loaded poly(ε-caprolactone)-poly(ethylene glycol)-poly(ε-caprolactone) nanoparticles: preparation, characterization and potential application in corneal transplantation

OBJECTIVES

Allograft rejection is the major cause of corneal graft failure. To inhibit corneal allograft rejection, rapamycin as a novel immunosuppressive agent has been discovered. However, the high water insolubility and low bioavailability of rapamycin has strongly hindered its application in the clinical setting. In this paper, we attempted to develop a novel rapamycin nano-formulation using poly(ε-caprolactone)-poly(ethylene glycol)-poly(ε-caprolactone) (PCEC) nanoparticles as carrier by an emulsion evaporation method for potential application in corneal transplantation.

METHODS

The solubility of rapamycin in the nano-formulation was determined and in-vitro release studies were performed. The developed rapamycin-loaded PCEC nanoparticles were further characterized by dynamic light scattering, transmission electron microscopy, X-ray diffraction and differential scanning calorimetery. Toxicity studies were performed in eye-related cell lines.

KEY FINDINGS

The rapamycin in nano-formulation exhibited ∼10³-fold increased solubility as compared with native rapamycin. According to the results of the in-vitro cytotoxicity assay, the developed PCEC nanoparticles did not exhibit any apparent cytotoxicity against various eye-related cell lines with PCEC nanoparticle concentrations in the range of 0.05-10 mg/ml. In-vitro release study showed that the release of rapamycin was sustained from PCEC nanoparticles over a period of 48 h.

CONCLUSIONS

All the results suggested that the developed rapamycin-loaded PCEC nanoparticles might be suitable for immunosuppression in corneal transplantation by instillation administration.

Characterization and antimicrobial property of poly(acrylic acid) nanogel containing silver particle prepared by electron beam

In this study, we developed a one step process to synthesize nanogel containing silver nanoparticles involving electron beam irradiation. Water-soluble silver nitrate powder is dissolved in the distilled water and then poly(acrylic acid) (PAAc) and hexane are put into this silver nitrate solution. These samples are irradiated by an electron beam to make the PAAc nanogels containing silver nanoparticles (Ag/PAAc nanogels). The nanoparticles were characterized by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). In addition, the particle size and zeta-potential were confirmed by a particle size analyzer (PSA). The antibacterial properties of the nanogels were evaluated by paper diffusion test. The Ag/PAAc nanogels had an antibacterial effect against Escherichia coli and Staphylococcus aureus. The nanogels also demonstrated a good healing effect against diabetic ulcer. The size of the Ag/PAAc nanogels decreased with increasing irradiation doses, and the absolute value of the zeta potential increased with increasing irradiation doses. Also, the Ag/PAAc nanogels exhibited good antibacterial activity against both Gram-negative and Gram-positive bacteria. In in vivo wound healing, the Ag/PAAc nanogels have a good healing effect.