Biodegradable polymeric nanoparticles based drug delivery systems

Diclofenac/biodegradable polymer micelles for ocular applications

In this paper, methoxypoly(ethylene glycol)-poly(ε-caprolactone) (MPEG-PCL) micelle formulations as promising nano-carriers for poorly water soluble drugs were investigated for the delivery of diclofenac to the eye. Diclofenac loaded MPEG-PCL micelles were prepared by a simple solvent-diffusion method and characterized by dynamic light scattering (DLS), atomic force microscopy (AFM), Fourier transform infra-red (FTIR), X-ray diffraction (XRD), differential scanning calorimetery (DSC), etc. With the analysis of XRD and DSC, the diclofenac was present as an amorphous state in the formulation. The in vitro release profile indicated a sustained release manner of diclofenac from the micelles. Meanwhile, in vivo studies on eye irritation were performed with blank MPEG-PCL micelles (200 mg ml(-1)). The results showed that the developed MPEG-PCL micelles were non-irritants to the eyes of rabbits. In vitro penetration studies across the rabbit cornea demonstrated that the micelle formulations exhibited a 17-fold increase in penetration compared with that of diclofenac phosphate buffered saline (PBS) solution. The in vivo pharmacokinetics profile of the micelle parent drug in the aqueous humor of the rabbit was evaluated and the data showed that the diclofenac loaded MPEG-PCL micelles exhibited a 2-fold increase in AUC(0-24 h) than that of the diclofenac PBS solution eye drops. These results suggest a great potential of our micelle formulations as a novel ocular drug delivery system to improve the bioavailability of the drugs.

Application of poly(ethylene glycol)-distearoylphosphatidylethanolamine (PEG-DSPE) block copolymers and their derivatives as nanomaterials in drug delivery

Poly(ethylene glycol)–distearoylphosphatidylethanolamine (PEG-DSPE) block copolymers are biocompatible and amphiphilic polymers that can be widely utilized in the preparation of liposomes, polymeric nanoparticles, polymer hybrid nanoparticles, solid lipid nanoparticles, lipid–polymer hybrid nanoparticles, and microemulsions. Particularly, the terminal groups of PEG can be activated and linked to various targeting ligands, which can prolong the circulation time, improve the drug bioavailability, reduce undesirable side effects, and especially target specific cells, tissues, and even the intracellular localization in organelles. This review herein aims to describe recent developments in drug carriers exploiting PEG-DSPE block copolymers and their derivatives, and the incorporation of different ligands to the end groups of PEG-DSPE to target delivery, focusing on their modification approaches, advantages, applications, and the probable associated drawbacks.

Amplified release through the stimulus triggered degradation of self-immolative oligomers, dendrimers, and linear polymers

In recent years, numerous delivery systems based on polymers, dendrimers, and nano-scale assemblies have been developed to improve the properties of drug molecules. In general, for the drug molecules to be active, they must be released from these delivery systems, ideally in a selective manner at the therapeutic target. As the changes in physiological conditions are relatively subtle from one tissue to another and the concentrations of specific enzymes are often quite low, a release strategy involving the amplification of a biological signal is particularly attractive. This article describes the development of oligomers, dendrimers, and linear polymers based on self-immolative spacers. This new class of molecules is designed to undergo a cascade of intramolecular reactions in response to the cleavage of a trigger moiety, resulting in molecular fragmentation and the release of multiple reporter or drug molecules. Progress in the development of these materials as drug delivery vehicles and sensors will be highlighted.

Polymeric particulate technologies for oral drug delivery and targeting: a pathophysiological perspective

The oral route for delivery of pharmaceuticals is the most widely used and accepted. Nanoparticles and microparticles are increasingly being applied within this arena to optimize drug targeting and bioavailability. Frequently the carrier systems used are either constructed from or contain polymeric materials. Examples of these nanocarriers include polymeric nanoparticles, solid lipid nanocarriers, self-nanoemulsifying drug delivery systems and nanocrystals. It is the purpose of this review to describe these cutting edge technologies and specifically focus on the interaction and fate of these polymers within the gastrointestinal system.

Plant extract synthesized PLA nanoparticles for controlled and sustained release of quercetin: a green approach

BACKGROUND

Green synthesis of metallic nanoparticles (NPs) has been extensively carried out by using plant extracts (PEs) which have property of stabilizers/emulsifiers. To our knowledge, there is no comprehensive study on applying a green approach using PEs for fabrication of biodegradable PLA NPs. Conventional methods rely on molecules like polyvinyl alcohol, polyethylene glycol, D-alpha-tocopheryl poly(ethylene glycol 1000) succinate as stabilizers/emulsifiers for the synthesis of such biodegradable NPs which are known to be toxic. So, there is urgent need to look for stabilizers which are biogenic and non-toxic. The present study investigated use of PEs as stabilizers/emulsifiers for the fabrication of stable PLA NPs. Synthesized PLA NPs through this green process were explored for controlled release of the well known antioxidant molecule quercetin.

METHODOLOGY/PRINCIPAL FINDINGS

Stable PLA NPs were synthesized using leaf extracts of medicinally important plants like Syzygium cumini (1), Bauhinia variegata (2), Cedrus deodara (3), Lonicera japonica (4) and Eleaocarpus sphaericus (5). Small and uniformly distributed NPs in the size range 70±30 nm to 143±36 nm were formed with these PEs. To explore such NPs for drugs/ small molecules delivery, we have successfully encapsulated quercetin a lipophilic molecule on a most uniformly distributed PLA-4 NPs synthesized using Lonicera japonica leaf extract. Quercetin loaded PLA-4 NPs were observed for slow and sustained release of quercetin molecule.

CONCLUSIONS

This green approach based on PEs mediated synthesis of stable PLA NPs pave the way for encapsulating drug/small molecules, nutraceuticals and other bioactive ingredients for safer cellular uptake, biodistribution and targeted delivery. Hence, such PEs synthesized PLA NPs would be useful to enhance the therapeutic efficacy of encapsulated small molecules/drugs. Furthermore, different types of plants can be explored for the synthesis of PLA as well as other polymeric NPs of smaller size.

Development of poly(glycerol adipate) nanoparticles loaded with non-steroidal anti-inflammatory drugs

The aim of this study was to assess acylated and non-acylated poly(glycerol adipate) polymers (PGA) as suitable nanoparticulate systems for encapsulation and release of ibuprofen, ibuprofen sodium salt (IBU-Na) and ketoprofen as model drugs. Drug encapsulated nanoparticles were prepared using the interfacial deposition method in the absence of surfactants. Physicochemical characterisation studies of the produced loaded nanoparticles showed that drug-polymer interactions depend on the characteristics of the actual active substance. IBU-Na showed strong interactions with the polymers and it was found to be molecularly dispersed within the polymer matrix while ibuprofen and ketoprofen retained their crystalline state. The drug release profiles showed stepwise patterns which involve an initial burst release effect, diffusion of the drug from the polymer matrix and eventually drug release possibly via a combined mechanism. PGA polymers can be effectively used as drug delivery carriers for various active substances.

Polymeric nanocarriers for controlled and enhanced delivery of therapeutic agents to the CNS

Polymeric nanocarriers are versatile structures that can be engineered to obtain high drug loading, good delivery yields and tunable release kinetics. Moreover, the particle surface can be modified for selective targeting of organs or tissues. In particular, polymeric nanocarriers can be conjugated with functional groups promoting translocation through the blood–brain barrier, thus providing a promising system to deliver therapeutic agents and/or diagnostic probes to the brain. Here we review recent literature on the preparation and characterization of polymeric nanoparticles as potential agents for drug delivery to the CNS, with an emphasis on materials chemistry and functionalization strategies for improved selectivity and delivery. Finally, we underline the immunotoxicological aspects of this class of nanostructured materials in view of potential clinical applications.

Physical and chemical strategies for therapeutic delivery by using polymeric nanoparticles

A significant challenge that most therapeutic agents face is their inability to be delivered effectively. Nanotechnology offers a solution to allow for safe, high-dose, specific delivery of pharmaceuticals to the target tissue. Nanoparticles composed of biodegradable polymers can be designed and engineered with various layers of complexity to achieve drug targeting that was unimaginable years ago by offering multiple mechanisms to encapsulate and strategically deliver drugs, proteins, nucleic acids, or vaccines while improving their therapeutic index. Targeting of nanoparticles to diseased tissue and cells assumes two strategies: physical and chemical targeting. Physical targeting is a strategy enabled by nanoparticle fabrication techniques. It includes using size, shape, charge, and stiffness among other parameters to influence tissue accumulation, adhesion, and cell uptake. New methods to measure size, shape, and polydispersity will enable this field to grow and more thorough comparisons to be made. Physical targeting can be more economically viable when certain fabrication techniques are used. Chemical targeting can employ molecular recognition units to decorate the surface of particles or molecular units responsive to diseased environments or remote stimuli. In this review, we describe sophisticated nanoparticles designed for tissue-specific chemical targeting that use conjugation chemistry to attach targeting moieties. Furthermore, we describe chemical targeting using stimuli responsive nanoparticles that can respond to changes in pH, heat, and light.

Pharmacokinetics of curcumin-loaded PLGA and PLGA-PEG blend nanoparticles after oral administration in rats

The aim of this study was to assess the potential of nanoparticles to improve the pharmacokinetics of curcumin, with a primary goal of enhancing its bioavailability. Polylactic-co-glycolic acid (PLGA) and PLGA-polyethylene glycol (PEG) (PLGA-PEG) blend nanoparticles containing curcumin were obtained by a single-emulsion solvent-evaporation technique, resulting in particles size smaller than 200 nm. The encapsulation efficiency was over 70% for both formulations. The in vitro release study showed that curcumin was released more slowly from the PLGA nanoparticles than from the PLGA-PEG nanoparticles. A LC-MS/MS method was developed and validated to quantify curcumin in rat plasma. The nanoparticles were orally administered at a single dose in rats, and the pharmacokinetic parameters were evaluated and compared with the curcumin aqueous suspension. It was observed that both nanoparticles formulations were able to sustain the curcumin delivery over time, but greater efficiency was obtained with the PLGA-PEG nanoparticles, which showed better results in all of the pharmacokinetic parameters analyzed. The PLGA and PLGA-PEG nanoparticles increased the curcumin mean half-life in approximately 4 and 6h, respectively, and the C(max) of curcumin increased 2.9- and 7.4-fold, respectively. The distribution and metabolism of curcumin decreased when it was carried by nanoparticles, particularly PLGA-PEG nanoparticles. The bioavailability of curcumin-loaded PLGA-PEG nanoparticles was 3.5-fold greater than the curcumin from PLGA nanoparticles. Compared to the curcumin aqueous suspension, the PLGA and PLGA-PEG nanoparticles increased the curcumin bioavailability by 15.6- and 55.4-fold, respectively. These results suggest that PLGA and, in particular, PLGA-PEG blend nanoparticles are potential carriers for the oral delivery of curcumin.

Chitosan/siRNA nanoparticles encapsulated in PLGA nanofibers for siRNA delivery

Composite nanofibers of biodegradable poly(D,L-lactic-co-glycolic acid) (PLGA) encapsulating chitosan/siRNA nanoparticles (NPs) were prepared by electrospinning. Acidic/alkaline hydrolysis and a bulk/surface degradation mechanism were investigated in order to achieve an optimized release profile for prolonged and efficient gene silencing. Thermo-controlled AFM in situ imaging not only revealed the integrity of the encapsulated chitosan/siRNA polyplex but also shed light on the decreasing T(g) of PLGA on the fiber surfaces during release. A triphasic release profile based on bulk erosion was obtained at pH 7.4, while a triphasic release profile involving both surface erosion and bulk erosion was obtained at pH 5.5. A short alkaline pretreatment provided a homogeneous hydrolysis and consequently a nearly zero-order release profile. The interesting release profile was further investigated for siRNA transfection, where the encapsulated chitosan/siRNA NPs exhibited up to 50% EGFP gene silencing activity after 48 h post-transfection on H1299 cells.

Preparation and characterization of polysaccharide-based nanoparticles with anticoagulant activity

The aim of this study was to produce and characterize nanoparticles (NPs), combining chondroitin sulfate (CS) and fucoidan (FC) with chitosan for therapeutic purposes. These NPs were characterized by dynamic light scattering, zeta potential determination, and transmission electronic microscopy. The anticoagulant activity was determined for FC NPs and compared with FC solution at the same concentration. FC NPs showed regular shapes and better anticoagulant activity than free polysaccharide solution. FC solution did not affect coagulation compared to FC NPs, which increased up to two-fold, even at a lower concentration. Cytotoxicity and permeability tests were conducted using Caco-2 cell monolayer, exhibiting no toxic effect in this cell line and higher permeability for NP2 samples than FC solution at the same concentration.

Chitosan-chondroitin sulphate nanoparticles for controlled delivery of platelet lysates in bone regenerative medicine

In this study, a new formulation of nanoparticles (NPs) based on the electrostatic interaction between chitosan and chondroitin sulphate (CH-CS NPs) is proposed for the controlled release of proteins and growth factors (GFs), specifically platelet lysates (PLs). These nanoparticulate carriers are particularly promising for protein entrapment because the interactions between the polysaccharides and the entrapped proteins mimic the interactions between chondroitin sulphate and proteins in the native extracellular matrix (ECM). Spherical non-cytotoxic NPs were successfully produced, exhibiting high encapsulation efficiency for physiological levels of GFs and a controlled protein release profile for > 1 month. Moreover, it was also observed that these NPs can be uptaken by human adipose-derived stem cells (hASCs), depending on the concentration of NPs in the culture medium and incubation time. This shows the versatility of the developed NPs, which, besides acting as a protein delivery system, can also be used in the future as intracellular carriers for bioactive agents, such as nucleotides. When the PL-loaded NPs were used as a replacement of bovine serum for in vitro hASCs culture, the viability and proliferation of hASCs was not compromised. The release of PLs from CH-CS NPs also proved to be effective for the enhancement of in vitro osteogenic differentiation of hASCs, as shown by the increased levels of mineralization, suggesting not only the effective role of the delivery system but also the role of PLs as an osteogenic supplement for bone tissue engineering and regenerative medicine applications.

Fabrication and evaluation of electrospun collagen/poly(N-isopropyl acrylamide)/chitosan mat as blood-contacting biomaterials for drug delivery

The recent advances in electrospinning have resulted in technologies facilitating easy drug entrapment, obtaining high surface area and thereby higher drug loading and release efficacy, burst control as well as the specific morphology which could be controlled according to the desired requirement. The present study focused on the fabrication of collagen/poly(N-isopropyl acrylamide)/chitosan complex with incorporated 5-fluorouracil, an anticancer drug by the method of electrospinning. The effect of chitosan on the fiber morphology and release kinetics was analyzed by varying its concentration. The release kinetics showed that the increase in chitosan concentration delayed the release of the drug from the fiber network. Nano hydroxyapatite was added to the fiber matrix in order to impart bioactivity, which was confirmed by studies in simulated body fluid. The addition of poly(N-isopropyl acrylamide) increased the blood compatibility of the prepared model. Thus, the model prepared to can find potential application in the field of cancer therapy as a drug-delivery agent in post-surgical treatment of cancer and as blood contacting biomaterial.

Probing aggregation and fibril formation of insulin in polyelectrolyte multilayers

Ultrathin films are useful for coating materials and controlling drug delivery processes. Here, we explore the use of polyelectrolyte multilayers as templates for the formation of two-dimensional protein networks, which represent biocompatible and biodegradable ultrathin films. In a first step, we have studied the lateral aggregation and amyloid fibril formation of bovine insulin that is adsorbed at and confined within planar polyelectrolyte multilayers, assembled with poly(diallyldimethylammonium chloride) (PDDA), poly(styrenesulfonic acid) (PSS), and hyaluronic acid (HA). Si-PDDA-PSS-(insulin-PSS)(x) and Si-PDDA-PSS-(insulin-HA)(x) multilayers (x=1-4) have been prepared and characterized in the fully hydrated state by using X-ray reflectometry, attenuated total reflection-Fourier transform infrared spectroscopy and confocal fluorescence microscopy. The obtained data demonstrate a successful build-up of the insulin-polyelectrolyte multilayers on silicon wafers that grow strongly in thickness upon insulin adsorption on PSS and HA layers. The secondary structure analysis of insulin, based on the vibrational amide I'-band, indicates an enhanced intermolecular β-sheet formation within the multilayers at 70°C and pD=2, i.e. at conditions that promote insulin amyloid fibrils rich in β-sheet contents. However, insulin that is confined between two polyelectrolyte layers rather forms amorphous aggregates as can be inferred from confocal fluorescence images. Remarkably, when insulin is deposited as the top-layer, a partial conversion into a two-dimensional fibrillar network can be induced by adding amyloid seeds to the solution. Thus, the results of this study illustrate the capability of polyelectrolyte multilayers as templates for the growth of protein networks.

Colloidal stability of polymeric nanoparticles in biological fluids

Estimating the colloidal stability of polymeric nanoparticles (NPs) in biological environments is critical for designing optimal preparations and to clarify the fate of these devices after administration. To characterize and quantify the physical stability of nanodevices suitable for biomedical applications, spherical NPs composed of poly-lactic acid (PLA) and poly-methyl-methacrylate (PMMA), in the range 100-200 nm, were prepared. Their stability in salt solutions, biological fluids, serum and tissue homogenates was analyzed by dynamic light scattering (DLS). The PMMA NPs remained stable in all fluids, while PLA NPs aggregated in gastric juice and spleen homogenate. The proposed stability test is therefore useful to see in advance whether NPs might aggregate when administered in vivo. To assess colloidal stability ex vivo as well, spectrophotofluorimetric analysis was employed, giving comparable results to DLS.

Toxicity studies of poly(anhydride) nanoparticles as carriers for oral drug delivery

PURPOSE

To evaluate the acute and subacute toxicity of poly(anhydride) nanoparticles as carriers for oral drug/antigen delivery.

METHODS

Three types of poly(anhydride) nanoparticles were assayed: conventional (NP), nanoparticles containing 2-hydroxypropyl-β-cyclodextrin (NP-HPCD) and nanoparticles coated with poly(ethylene glycol) 6000 (PEG-NP). Nanoparticles were prepared by a desolvation method and characterized in terms of size, zeta potential and morphology. For in vivo oral studies, acute and sub-acute toxicity studies were performed in rats in accordance to the OECD 425 and 407 guidelines respectively. Finally, biodistribution studies were carried out after radiolabelling nanoparticles with (99m)technetium.

RESULTS

Nanoparticle formulations displayed a homogeneous size of about 180 nm and a negative zeta potential. The LD(50) for all the nanoparticles tested was established to be higher than 2000 mg/kg bw. In the sub-chronic oral toxicity studies at two different doses (30 and 300 mg/kg bw), no evident signs of toxicity were found. Lastly, biodistribution studies demonstrated that these carriers remained in the gut with no evidences of particle translocation or distribution to other organs.

CONCLUSIONS

Poly(anhydride) nanoparticles (either conventional or modified with HPCD or PEG6000) showed no toxic effects, indicating that these carriers might be a safe strategy for oral delivery of therapeutics.

Preparation of biocompatible chitosan grafted poly(lactic acid) nanoparticles

Chitosan grafted poly(lactic acid) (CS-g-PLA) copolymer was synthesized and characterized by FT-IR and elemental analysis. The degree of poly(lactic acid) substitution on chitosan was 1.90 ± 0.04%. The critical aggregation concentration of CS-g-PLA in distilled water was 0.17 mg/ml. Three methods of preparing CS-g-PLA nanoparticles (diafiltration method, ultrasonication method and diafiltration combined with ultrasonication method) were investigated and their effect was compared. Of the three methods, diafiltration combined with ultrasonication method produced nanoparticles with optimal property in terms of size and morphology, with size ranging from 133 to 352 nm and zeta potential from 36 to 43 mV. Also, the hemolytic activity and cytotoxicity of the CS-g-PLA based nanoparticles was tested, and results showed low hemolysis rate (<5%) and no significant cytotoxicity effect of these nanoparticles.

Polyelectrolyte multilayer nanoshells with hydrophobic nanodomains for delivery of Paclitaxel

Efficient and effective delivery of poorly water-soluble drug molecules, which constitute a large part of commercially available drugs, is a major challenge in the field of drug delivery. Several drugs including paclitaxel (PTX) which are used for cancer treatment are hydrophobic, exhibit poor aqueous solubility and need to be delivered using an appropriate carrier. In the present work, we engineered PTX-loaded polyelectrolyte films and microcapsules by pre-complexing PTX with chemically modified derivative of hyaluronic acid (alkylamino hydrazide) containing hydrophobic nanocavities, and subsequent assembly with either poly(l-lysine) (PLL) or quaternized chitosan (QCHI) as polycations. The PTX loading capacity of the films was found to be dependent on number of layers in the films as well as on the initial concentration of PTX pre-complexed to hydrophobic HA, with a loading capacity up to 5000-fold the initial PTX concentration. The films were stable in physiological medium and were degraded in the presence of hyaluronidase. The PTX-loaded microcapsules were found to decrease the viability and proliferation of MDA MB 231 breast cancer cells, while unloaded microcapsules did not impact cell viability. All together, our results highlight the potential of hyaluronan-based assemblies containing hydrophobic nanodomains for hydrophobic drug delivery.

Exploring uptake mechanisms of oral nanomedicines using multimodal nonlinear optical microscopy

Advances in pharmaceutical nanotechnology have yielded ever increasingly sophisticated nanoparticles for medicine delivery. When administered via oral, intravenous, ocular and transcutaneous delivery routes, these nanoparticles can elicit enhanced drug performance. In spite of this, little is known about the mechanistic processes underlying interactions between nanoparticles and tissues, or how these correlate with improved pharmaceutical effects. These mechanisms must be fully understood before nanomedicines can be rationally engineered to optimise their performance. Methods to directly visualise these particulates within tissue samples have traditionally involved imaging modalities requiring covalent labelling of fluorescent or radioisotope contrast agents. We present CARS, second harmonic generation and two photon fluorescence microscopy combined as a multi-modal label-free method for pinpointing polymeric nanoparticles within the stomach, intestine, gall bladder and liver. We demonstrate for the first time that orally administered chitosan nanoparticles follow a recirculation pathway from the GI tract via enterocytes, to the liver hepatocytes and intercellular spaces and then to the gall bladder, before being re-released into the gut together with bile.

Nanoparticles labeled with positron emitting nuclides: advantages, methods, and applications

Over the past decade, positron emitter labeled nanoparticles have been widely used in and substantially improved for a range of diagnostic biomedical research. However, given growing interest in personalized medicine and translational research, a major challenge in the field will be to develop disease-specific nanoprobes with facile and robust radiolabeling strategies and that provide imaging stability, enhanced sensitivity for disease early stage detection, optimized in vivo pharmacokinetics for reduced nonspecific organ uptake, and improved targeting for elevated efficacy. This review briefly summarizes the major applications of nanoparticles labeled with positron emitters for cardiovascular imaging, lung diagnosis, and tumor theranostics.

Nanoparticulate adjuvants and delivery systems for allergen immunotherapy

In the last decades, significant progress in research and clinics has been made to offer possible innovative therapeutics for the management of allergic diseases. However, current allergen immunotherapy shows limitations concerning the long-term efficacy and safety due to local side effects and risk of anaphylaxis. Thus, effective and safe vaccines with reduced dose of allergen have been developed using adjuvants. Nevertheless, the use of adjuvants still has several disadvantages, which limits its use in human vaccines. In this context, several novel adjuvants for allergen immunotherapy are currently being investigated and developed. Currently, nanoparticles-based allergen-delivery systems have received much interest as potential adjuvants for allergen immunotherapy. It has been demonstrated that the incorporation of allergens into a delivery system plays an important role in the efficacy of allergy vaccines. Several nanoparticles-based delivery systems have been described, including biodegradable and nondegradable polymeric carriers. Therefore, this paper provides an overview of the current adjuvants used for allergen immunotherapy. Furthermore, nanoparticles-based allergen-delivery systems are focused as a novel and promising strategy for allergy vaccines.

Surface decoration by Spirulina polysaccharide enhances the cellular uptake and anticancer efficacy of selenium nanoparticles

A simple and solution-phase method for functionalization of selenium nanoparticles (SeNPs) with Spirulina polysaccharides (SPS) has been developed in the present study. The cellular uptake and anticancer activity of SPS-SeNPs were also evaluated. Monodisperse and homogeneous spherical SPS-SeNPs with diameters ranging from 20 nm to 50 nm were achieved under optimized conditions, which were stable in the solution phase for at least 3 months. SPS surface decoration significantly enhanced the cellular uptake and cytotoxicity of SeNPs toward several human cancer cell lines. A375 human melanoma cells were found extremely susceptible to SPS-SeNPs with half maximal (50%) inhibitory concentration value of 7.94 μM. Investigation of the underlying mechanisms revealed that SPS-SeNPs inhibited cancer cell growth through induction of apoptosis, as evidenced by an increase in sub-G(1) cell population, deoxyribonucleic acid fragmentation, chromatin condensation, and phosphatidylserine translocation. Results suggest that the strategy to use SPS as a surface decorator could be an effective way to enhance the cellular uptake and anticancer efficacy of nanomaterials. SPS-SeNPs may be a potential candidate for further evaluation as a chemopreventive and chemotherapeutic agent against human cancers.

Pseudomonas sp. as a Source of Medium Chain Length Polyhydroxyalkanoates for Controlled Drug Delivery: Perspective

Controlled drug delivery technology represents one of the most rapidly advancing areas of science. They offer numerous advantages compared to conventional dosage forms including improved efficacy, reduced toxicity, improved patient compliance and convenience. Over the past several decades, many delivery tools or methods were developed such as viral vector, liposome-based delivery system, polymer-based delivery system, and intelligent delivery system. Recently, nonviral vectors, especially those based on biodegradable polymers, have been widely investigated as vectors. Unlike the other polymers tested, polyhydroxyalkanoates (PHAs) have been intensively investigated as a family of biodegradable and biocompatible materials for in vivo applications as implantable tissue engineering material as well as release vectors for various drugs. On the other hand, the direct use of these polyesters has been hampered by their hydrophobic character and some physical shortcomings, while its random copolymers fulfilled the expectation of biomedical researchers by exhibiting significant mechanical and thermal properties. This paper reviews the strategies adapted to make functional polymer to be utilized as delivery system.

PLGA-based nanoparticles: an overview of biomedical applications

Poly(lactic-co-glycolic acid) (PLGA) is one of the most successfully developed biodegradable polymers. Among the different polymers developed to formulate polymeric nanoparticles, PLGA has attracted considerable attention due to its attractive properties: (i) biodegradability and biocompatibility, (ii) FDA and European Medicine Agency approval in drug delivery systems for parenteral administration, (iii) well described formulations and methods of production adapted to various types of drugs e.g. hydrophilic or hydrophobic small molecules or macromolecules, (iv) protection of drug from degradation, (v) possibility of sustained release, (vi) possibility to modify surface properties to provide stealthness and/or better interaction with biological materials and (vii) possibility to target nanoparticles to specific organs or cells. This review presents why PLGA has been chosen to design nanoparticles as drug delivery systems in various biomedical applications such as vaccination, cancer, inflammation and other diseases. This review focuses on the understanding of specific characteristics exploited by PLGA-based nanoparticles to target a specific organ or tissue or specific cells.

Effect of chitosan multilayers encapsulation on controlled release performance of drug-loaded superparamagnetic alginate nanoparticles

The near monodispersed ibuprofen-loaded superparamagnetic alginate (AL/IBU/Fe(3)O(4)) nanoparticles with particles size less than 200 nm were prepared via the facile heterogeneous coprecipitation of the superparamagnetic Fe(3)O(4) nanoparticles, sodium alginate (AL) and the model drug ibuprofen (IBU) from the aqueous dispersion. Then the chitosan multilayers were self-assembled onto the AL/IBU/Fe(3)O(4) nanoparticles to produce novel magnetic-targeted controlled release drug delivery system, with chitosan as the polycation (CS) and the carboxymethyl chitosan (CMCS) as the polyanion. The drug controlled releasing behaviors of the AL/IBU/Fe(3)O(4) nanoparticles and the CS multilayers encapsulated ibuprofen-loaded superparamagnetic alginate ((AL/IBU/Fe(3)O(4))@(CS-CMCS)(3)) nanoparticles were compared in the different pH media. In media with the same pH value, the encapsulated vessels exhibited the slower releasing rate.

Tamoxifen-loaded nanoparticles based on a novel mixture of biodegradable polyesters: characterization and in vitro evaluation as sustained release systems

Nanoparticles (NP) from mixtures of two poly(D,L-lactide-co-caprolactone) (PLC) copolymers, PLC 40/60 and PLC 86/14, with poly(D,L-lactide) (PDLLA) and PCL were prepared: PLC 40/60-PCL (25:75), PLC 86/14-PCL (75:25) and PLC 86/14-PLA (75:25). Tamoxifen was loaded with encapsulation efficiency between 65% and 75% (29.9-36.3 µg TMX/ mg NP). All selected systems showed spherical shape and nano-scale size. TMX-loaded NPs were in the range of 293-352 nm. TMX release from NP took place with different profiles depending on polymeric composition of the particles. After 60 days, 59.81% and 82.65% of the loaded drug was released. The cytotoxicity of unloaded NP in MCF7 and HeLa cells was very low. Cell uptake of NP took place in both cell types by unspecific internalization in a time dependent process. The administration of 6 and 10 µm TMX by TMX-loaded NP was effective on both cellular types, mainly in MCF7 cells.

Polymeric and Ceramic Nanoparticles in Biomedical Applications

Materials in the nanometer size range may possess unique and beneficial properties, which are very useful for different medical applications including stomatology, pharmacy, and implantology tissue engineering. The application of nanotechnology to medicine, known as nanomedicine, concerns the use of precisely engineered materials at this length scale to develop novel therapeutic and diagnostic modalities. Nanomaterials have unique physicochemical properties, such as small size, large surface area to mass ratio, and high reactivity, which are different from bulk materials of the same composition. Polymeric and ceramic nanoparticles have been extensively studied as particulate carriers in the pharmaceutical and medical fields, because they show promise as drug delivery systems as a result of their controlled- and sustained-release properties, subcellular size, and biocompatibility with tissue and cells. These properties can be used to overcome some of the limitations found in traditional therapeutic and diagnostic agents. Nanotechnology is showing promising developments in many areas and may benefit our health and welfare. However, a wide range of ethical issues has been raised by this innovative science. Many authorities believe that these advancements could lead to irreversible disasters if not limited by ethical guidelines.

Improved anti-proliferative effect of doxorubicin-containing polymer nanoparticles upon surface modification with cationic groups

Polymer nanoparticles (PNPs) possessing a high density of drug payload have been successfully stabilized against aggregation in biological buffers after amine modification, which renders these PNPs positively charged. The resulting charge-stabilized PNPs retain their original narrow particle size distributions and well-defined spherical morphologies. This stabilization allows these PNPs to have an improved anti-proliferative effect on MDA-MB-231-Br human breast cancer cells compared to non-functionalized PNPs. As a non-cytotoxic control, similar surface-modified PNPs containing cholesterol in place of doxorubicin did not inhibit cell proliferation, indicating that the induced cytotoxic response was solely due to the doxorubicin release from the PNPs.

Nanomedicine as an emerging approach against intracellular pathogens

Diseases such as tuberculosis, hepatitis, and HIV/AIDS are caused by intracellular pathogens and are a major burden to the global medical community. Conventional treatments for these diseases typically consist of long-term therapy with a combination of drugs, which may lead to side effects and contribute to low patient compliance. The pathogens reside within intracellular compartments of the cell, which provide additional barriers to effective treatment. Therefore, there is a need for improved and more effective therapies for such intracellular diseases. This review will summarize, for the first time, the intracellular compartments in which pathogens can reside and discuss how nanomedicine has the potential to improve intracellular disease therapy by offering properties such as targeting, sustained drug release, and drug delivery to the pathogen’s intracellular location. The characteristics of nanomedicine may prove advantageous in developing improved or alternative therapies for intracellular diseases.