Arterial uptake of biodegradable nanoparticles for intravascular local drug delivery: results with an acute dog model

The evolution and revolution of drug coated balloons in coronary angioplasty: An up-to-date review of literature data

European Society of Cardiology (ESC) guidelines gave class I A indication for use of DCB in in-stent restenosis. However, no indication exists for the usage of DCB in de novo lesions. Although the current generation DES offer excellent results, as we embark more complex lesions such as calcified lesion and chronic total occlusion, restenosis and stent thrombosis are higher and tend to increase within the years. There is increasing desire to leave nothing behind to abolish the risk of restenosis and stent thrombosis and hence the absorbable scaffolds were introduced, but with disappointing results. In addition, they take several years to be absorbed. Drug coated balloons offer an alternative to stents with no permanent implant of metal or polymer. They are already in use in in Europe and Asia and they have been approved for the first time in the United States for clinical trials specifically for restenotic lesions. There is emerging data in de novo lesions which have shown that DCB are noninferior and in some studies maybe even superior to current generation DES especially in small vessels. In this article, we provide a comprehensive review of the literature on this expanding technology focussing on the evidence in both re-stenotic and de novo lesions.

Role of Nanoparticle-Conjugates and Nanotheranostics in Abrogating Oxidative Stress and Ameliorating Neuroinflammation

Oxidative stress is a deteriorating condition that arises due to an imbalance between the reactive oxygen species and the antioxidant system or defense of the body. The key reasons for the development of such conditions are malfunctioning of various cell organelles, such as mitochondria, endoplasmic reticulum, and Golgi complex, as well as physical and mental disturbances. The nervous system has a relatively high utilization of oxygen, thus making it particularly vulnerable to oxidative stress, which eventually leads to neuronal atrophy and death. This advances the development of neuroinflammation and neurodegeneration-associated disorders such as Alzheimer's disease, Parkinson's disease, epilepsy, dementia, and other memory disorders. It is imperative to treat such conditions as early as possible before they worsen and progress to irreversible damage. Oxidative damage can be negated by two mechanisms: improving the cellular defense system or providing exogenous antioxidants. Natural antioxidants can normally handle such oxidative stress, but they have limited efficacy. The valuable features of nanoparticles and/or nanomaterials, in combination with antioxidant features, offer innovative nanotheranostic tools as potential therapeutic modalities. Hence, this review aims to represent novel therapeutic approaches like utilizing nanoparticles with antioxidant properties and nanotheranostics as delivery systems for potential therapeutic applications in various neuroinflammation- and neurodegeneration-associated disease conditions.

Targeted Nanoparticles for the Binding of Injured Vascular Endothelium after Percutaneous Coronary Intervention

Percutaneous coronary intervention (PCI) is a common procedure for the management of coronary artery obstruction. However, it usually causes vascular wall injury leading to restenosis that limits the long-term success of the PCI endeavor. The ultimate objective of this study was to develop the targeting nanoparticles (NPs) that were destined for the injured subendothelium and attract endothelial progenitor cells (EPCs) to the damaged location for endothelium regeneration. Biodegradable poly(lactic-co-glycolic acid) (PLGA) NPs were conjugated with double targeting moieties, which are glycoprotein Ib alpha chain (GPIbα) and human single-chain antibody variable fragment (HuscFv) specific to the cluster of differentiation 34 (CD34). GPIb is a platelet receptor that interacts with the von Willebrand factor (vWF), highly deposited on the damaged subendothelial surface, while CD34 is a surface marker of EPCs. A candidate anti-CD34 HuscFv was successfully constructed using a phage display biopanning technique. The HuscFv could be purified and showed binding affinity to the CD34-positive cells. The GPIb-conjugated NPs (GPIb-NPs) could target vWF and prevent platelet adherence to vWF in vitro. Furthermore, the HuscFv-conjugated NPs (HuscFv-NPs) could capture CD34-positive cells. The bispecific NPs have high potential to locate at the damaged subendothelial surface and capture EPCs for accelerating the vessel repair.

Synthesis of M-Ag3PO4, (M = Se, Ag, Ta) Nanoparticles and Their Antibacterial and Cytotoxicity Study

Silver Phosphate, Ag3PO4, being a highly capable clinical molecule, an ultrasonic method was employed to synthesize the M-Ag3PO4, (M = Se, Ag, Ta) nanoparticles which were evaluated for antibacterial and cytotoxicity activities post-characterization. Escherichia coli and Staphylococcus aureus were used for antibacterial testing and the effects of sonication on bacterial growth with sub-MIC values of M-Ag3PO4 nanoparticles were examined. The effect of M-Ag3PO4 nanoparticles on human colorectal carcinoma cells (HCT-116) and human cervical carcinoma cells (HeLa cells) was examined by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide) assay and DAPI (4′,6-diamidino-2-phenylindole) staining. Additionally, we analyzed the effect of nanoparticles on normal and non-cancerous human embryonic kidney cells (HEK-293). Ag-Ag3PO4 exhibited enhanced antibacterial activity followed by Ta-Ag3PO4, Ag3PO4, and Se-Ag3PO4 nanoparticles against E. coli. Whereas the order of antibacterial activity against Staphylococcus aureus was Ag3PO4 > Ag-Ag3PO4 > Ta-Ag3PO4 > Se-Ag3PO4, respectively. Percentage inhibition of E. coli was 98.27, 74.38, 100, and 94.2%, while percentage inhibition of S. aureus was 25.53, 80.28, 99.36, and 20.22% after treatment with Ag3PO4, Se-Ag3PO4, Ag-Ag3PO4, and Ta-Ag3PO4, respectively. The MTT assay shows a significant decline in the cell viability after treating with M-Ag3PO4 nanoparticles. The IC50 values for Ag3PO4, Se-Ag3PO4, Ag-Ag3PO4, and Ta-Ag3PO4 on HCT-116 were 39.44, 28.33, 60.24, 58.34 µg/mL; whereas for HeLa cells, they were 65.25, 61.27, 75.52, 72.82 µg/mL, respectively. M-Ag3PO4 nanoparticles did not inhibit HEK-293 cells. Apoptotic assay revealed that the numbers of DAPI stained cells were significantly lower in the M-Ag3PO4-treated cells versus control.

The Influence of Surface Charge on the Antiviral Effect of Curcumin Loaded in Nanocarrier System

BACKGROUND

Curcumin is a well-documented bioactive compound present in Curcuma sp., a tropical, medicinal plant. This substance exhibits broad-spectrum biological activities, including antivirus. Despite the lack of pharmaceutical properties of curcumin limits its clinical use.

OBJECTIVE

This study aims to produce curcumin nanoemulsion with different surface charge (curcumin (+) nanoemulsion and curcumin (-) nanoemulsion) and to evaluate its physical characteristics, in vitro cell cytotoxicity, and antiviral activity against dengue virus (DENV) 1 and 2.

METHODS

Two forms of nanoemulsion were prepared, which were differed from their surface charge through spontaneous procedure resulting in similar characteristics except for the zeta potential value. Cytotoxicity was determined using the RT-PCR method in the A549 cell line, and anti- DENV properties were determined by calculation of inhibitory concentration 50 (IC₅₀) value.

RESULTS

The positive charge of curcumin-loaded nanoemulsion showed a better effect in reducing the viral replication represented by a lower IC₅₀ value. In addition, DENV-1 was more sensitive and responsive to curcumin as compared to DENV-2.

CONCLUSION

Positive surface charge of curcumin-loaded nanoemulsion improves the antiviral effect of the curcumin, suggesting a promising approach for alternative treatment for dengue virus infection.

Comprehensive evaluation of chitosan nanoparticle based phage lysin delivery system; a novel approach to counter S. pneumoniae infections

Cpl-1, an endolysin derived from Cp-1 phage has been found to be effective in a number of in-vitro and in-vivo pneumococcal infection models. However its lower bioavailability under in-vivo conditions limits its applicability as therapeutic agent. In this study, Cpl-1 loaded chitosan nanoparticles were set up in order to develop a novel therapeutic delivery system to counter antibiotic resistant S. pneumoniae infections. Interactions of chitosan and Cpl-1 were studied by in-silico docking analysis. Chitosan nanoparticles and Cpl-1 loaded chitosan nanoparticles were prepared by using ionic gelation method and the process was optimized by varying chitosan:TPP ratio, pH, stirring time, stirring rate and Cpl-1 concentration. Chitosan nanoparticles and Cpl-1 loaded chitosan nanoparticles were characterized to ascertain successful formation of nanoparticles and entrapment of Cpl-1 into nanoparticles. Chitosan nanoparticles and Cpl-1 loaded nanoparticles were also evaluated for nanoparticle yield, entrapment efficiency, in-vitro release, stability, structural integrity of Cpl-1, in-vitro bioassay, swelling studies, in-vitro biodegradation and heamolysis studies. Mucoadhesion behavior of chitosan nanoparticles and Cpl-1 loaded nanoparticles was explored using mucous glycoprotein assay and ex-vivo mucoadhesion assay, both preparations exhibited their mucoadhesive nature. Cellular cytotoxicity and immune stimulation studies revealed biocompatible nature of nanoparticles. The results of this study confirm that chitosan nanoparticles are a promising biocompatible candidate for Cpl-1 delivery with a significant potential to increase bioavailability of enzyme that in turn can increase its in-vivo half life to treat S. pneumoniae infections.

Nanoparticle eluting-angioplasty balloons to treat cardiovascular diseases

Nanoparticles (NPs) can be used to locally deliver anti-restenosis drugs when they are infused directly to the injured arteries after intervention procedures such as angioplasty. However, the efficacy of transferring NPs via infusion to the arterial wall is limited, at least partially, due to poor NP retention on the inner artery wall. To improve NP retention, angioplasty balloons coated with drug-loaded NPs were fabricated via either layer-by-layer (LbL) electrostatic coating or acrylic-based hydrogel (AAH) coating techniques. Three types of NPs, namely poly (lactide-co-glycolide) (PLGA), biodegradable photo-luminescent PLGA and urethane doped polyester were studied. The transfer efficacy of NPs from various coatings to the arterial wall were further evaluated to find the optimal coating conditions. The ex vivo NP transfer studies showed significantly more NPs being transferred to the rat arterial wall after the angioplasty procedure by the AAH coating (95% transfer efficiency) compared to that of the LbL technique (60%) and dip coating (20%) under flow conditions (10 dyn/cm²). Our results suggest that the AAH coating of drug-loaded NPs on the angioplasty balloon could potentially provide superior retention of drug-loaded NPs onto the arterial wall for a better local delivery of drug-loaded NPs to effectively treat arterial diseases.

Formulation and Pharmacokinetics of HSA-core and PLGA-shell Nanoparticles for Delivering Gemcitabine

Gemcitabine-loaded core-shell nanoparticles (CSNPs), comprised of a cross-linked HSA-core and PLGA-shell, were prepared through a modified double emulsification method, and the processing parameters were systematically investigated. The optimized CSNPs had a particle size of 241 ± 36.2 nm and an encapsulation efficiency of 41.52%. The core-shell structure was characterized by optical microscope (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The amorphous nature of the encapsulated drug was confirmed by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). An in vitro release study demonstrated that the CSNPs had an improved sustained release profile controlled by erosion of materials in combination with drug diffusion. In vivo pharmacokinetics of CSNPs obtained a bigger area under concentration-time curve (AUC), t _1/2, and C _max compared to free drug solution. The results suggest that HSA-PLGA-based CSNPs can be a promising carrier for the sustained release of gemcitabine.

Physicochemical characteristics of liposomes are decisive for their antirestenosis efficacy following local delivery

AIM

To develop an ameliorated sirolimus (SIR) liposome for intramural delivery, the effects of various carrier physicochemical parameters on the antirestenosis efficacy were evaluated.

MATERIALS & METHODS

Different liposomes were prepared, characterized and administered to balloon injured rats (12 animal groups). Their efficacies were investigated using morphometric, immunohistochemical and in vivo computed tomography imaging analyses.

RESULTS

The antirestenosis efficacy of SIR liposomes decreased in the following order: cationic 100 nm vesicles ≥ cationic 60 nm vesicles > neutral 100 nm vesicles ≥ stealth 100 nm vesicles > anionic 100 nm vesicles. The 100 µg SIR loaded in cationic liposomes showed almost no artery stenosis.

CONCLUSION

Appropriate modulation of physicochemical characteristics makes it possible to optimize the liposomes for local delivery.

Mesoscale nanoparticles selectively target the renal proximal tubule epithelium

We synthesized "mesoscale" nanoparticles, approximately 400 nm in diameter, which unexpectedly localized selectively in renal proximal tubules and up to 7 times more efficiently in the kidney than other organs. Although nanoparticles typically localize in the liver and spleen, modulating their size and opsonization potential allowed for stable targeting of the kidneys through a new proposed uptake mechanism. Applying this kidney targeting strategy, we anticipate use in the treatment of renal disease and the study of renal physiology.

Formulation of nanotized curcumin and demonstration of its antimalarial efficacy

Aim

The present study was conducted to overcome the disadvantages associated with the poor water solubility and low bioavailability of curcumin by synthesizing nanotized curcumin and demonstrating its efficacy in treating malaria.

Materials and methods

Nanotized curcumin was prepared by a modified emulsion-diffusion-evaporation method and was characterized by means of transmission electron microscopy, atomic force microscopy, dynamic light scattering, Zetasizer, Fourier transform infrared spectroscopy, and differential thermal analysis. The novelty of the prepared nanoformulation lies in the fact that it was devoid of any polymeric matrices used in conventional carriers. The antimalarial efficacy of the prepared nanotized curcumin was then checked both in vitro and in vivo.

Results

The nanopreparation was found to be non-toxic and had a particle size distribution of 20–50 nm along with improved aqueous dispersibility and an entrapment efficiency of 45%. Nanotized curcumin (half maximal inhibitory concentration [IC₅₀]: 0.5 μM) was also found to be ten-fold more effective for growth inhibition of Plasmodium falciparum in vitro as compared to its native counterpart (IC₅₀: 5 μM). Oral bioavailability of nanotized curcumin was found to be superior to that of its native counterpart. Moreover, when Plasmodium berghei-infected mice were orally treated with nanotized curcumin, it prolonged their survival by more than 2 months with complete clearance of parasites in comparison to the untreated animals, which survived for 8 days only.

Conclusion

Nanotized curcumin holds a considerable promise in therapeutics as demonstrated here for treating malaria as a test system.

In situ re-endothelialization via multifunctional nanoscaffolds

The endothelium monolayer lining in the luminal side of blood vessels provides critical antithrombotic functions. Damage to these cells will expose a highly thrombogenic subendothelium, which leads to pathological vascular changes. Using combined tissue engineering and ligand-receptor targeting strategy, we developed a biodegradable urethane-doped polyester (UPE) multifunctional targeting nanoparticle (MTN) scaffold system with dual ligands: (1) glycoprotein 1b (GP1b) to target the injured arterial endothelium and subendothelium and (2) anti-CD34 antibodies to capture endothelial progenitor cells for endothelium regeneration. The fabricated spherical MTNs of 400 nm were found to be cytocompatible and hemocompatible. Both the in vitro and ex vivo targeting of these nanoscaffolds not only showed binding specificity of MTNs onto the von Willebrand factor -coated surfaces that simulate the injured arterial walls but also competed with platelets for binding onto these injured sites. Further in vivo study has revealed that a single delivery of MTNs upon vascular injury reduced neointimal hyperplasia by 57% while increased endothelium regeneration by ∼ 60% in 21 days. These results support the promise of using MTN nanoscaffolds for treating vascular injury in situ.

Recent advancements in the cardiovascular drug carriers

Cardiovascular disease is the disease that affects the cardiovascular system, vascular diseases of the brain and kidney, and peripheral arterial disease. Despite of all advances in pharmacological and clinical treatment, heart failure is a leading cause of morbidness and mortality worldwide. Many new therapeutic advance strategies, including cell transplantation, gene delivery or therapy, and cytokines or other small molecules, have been research to treat heart failure. The main aim of this review article is to focus on nano carriers advancement and addressing the problems associated with old and modern therapeutics such as nonspecific effects and poor stability.

Challenges associated with Penetration of Nanoparticles across Cell and Tissue Barriers: A Review of Current Status and Future Prospects

Nanoparticles (NPs) have emerged as an effective modality for the treatment of various diseases including cancer, cardiovascular and inflammatory diseases. Various forms of NPs including liposomes, polymer particles, micelles, dendrimers, quantum dots, gold NPs and carbon nanotubes have been synthesized and tested for therapeutic applications. One of the greatest challenges that limit the success of NPs is their ability to reach the therapeutic site at necessary doses while minimizing accumulation at undesired sites. The biodistribution of NPs is determined by body's biological barriers that manifest in several distinct ways. For intravascular delivery of NPs, the barrier manifests in the form of: (i) immune clearance in the liver and spleen, (ii) permeation across the endothelium into target tissues, (iii) penetration through the tissue interstitium, (iv) endocytosis in target cells, (v) diffusion through cytoplasm and (vi) eventually entry into the nucleus, if required. Certain applications of NPs also rely on delivery through alternate routes including skin and mucosal membranes of the nose, lungs, intestine and vagina. In these cases, the diffusive resistance of these tissues poses a significant barrier to delivery. This review focuses on the current understanding of penetration of NPs through biological barriers. Emphasis is placed on transport barriers and not immunological barriers. The review also discusses design strategies for overcoming the barrier properties.

Abdominal aortic aneurysms targeted by functionalized polysaccharide microparticles: a new tool for SPECT imaging

Aneurysm diagnostic is nowadays limited by the lack of technology that enables early detection and rupture risk prediction. New non invasive tools for molecular imaging are still required. In the present study, we present an innovative SPECT diagnostic tool for abdominal aortic aneurysm (AAA) produced from injectable polysaccharide microparticles radiolabeled with technetium 99m (^99mTc) and functionalized with fucoidan, a sulfated polysaccharide with the ability to target P-Selectin. P-Selectin is a cell adhesion molecule expressed on activated endothelial cells and platelets which can be found in the thrombus of aneurysms, as well as in other vascular pathologies.

Microparticles with a maximum hydrodynamic diameter of 4 µm were obtained by crosslinking the polysaccharides dextran and pullulan. They were functionalized with fucoidan. In vitro interactions with human activated platelets were assessed by flow cytometry that demonstrated a specific affinity of fucoidan functionalized microparticles for P-Selectin expressed by activated platelets. For in vivo AAA imaging, microparticles were radiolabeled with ^99mTc and intravenously injected into healthy and AAA rats obtained by elastase perfusion through the aorta wall. Animals were scanned by SPECT imaging. A strong contrast enhancement located in the abdominal aorta of AAA rats was obtained, while no signal was obtained in healthy rats or in AAA rats after injection of non-functionalized control microparticles. Histological studies revealed that functionalized radiolabeled polysaccharide microparticles were localized in the AAA wall, in the same location where P-Selectin was expressed.

These microparticles therefore constitute a promising SPECT imaging tool for AAA and potentially for other vascular diseases characterized by P-Selectin expression. Future work will focus on validating the efficiency of the microparticles to diagnose these other pathologies and the different stages of AAA. Incorporation of a therapeutic molecule is also considered.

Nanoparticle targeting to diseased vasculature for imaging and therapy

Significant challenges remain in targeting drugs to diseased vasculature; most important being rapid blood flow with high shear, limited availability of stable targets, and heterogeneity and recycling of cellular markers. We developed nanoparticles (NPs) to target degraded elastic lamina, a consistent pathological feature in vascular diseases. In-vitro organ and cell culture experiments demonstrated that these NPs were not taken up by cells, but instead retained within the extracellular space; NP binding was proportional to the extent of elastic lamina damage. With three well-established rodent models of vascular diseases such as aortic aneurysm (calcium chloride mediated aortic injury in rats), atherosclerosis (fat-fed apoE-/- mice), and vascular calcification (warfarin + vitamin K injections in rats), we show precise NPs spatial targeting to degraded vascular elastic lamina while sparing healthy vasculature when NPs were delivered systemically. Nanoparticle targeting degraded elastic lamina is attractive to deliver therapeutic or imaging agents to the diseased vasculature.

FROM THE CLINICAL EDITOR

This novel work focuses on nanoparticle targeting of degraded elastic lamina in a variety of diseases, including atherosclerosis, vascular calcification, and aneurysm formation, and demonstrates the feasibility to deliver therapeutic or imaging agents to the diseased vasculature.

Synthesis and Characterization of Iron Oxide Nanoparticles

Iron oxide nanoparticles show great promise in bio-applications like drug delivery, magnetic resonance imaging, and hyperthermia. This is because the size of these magnetic nanoparticles is comparable to biomolecules and the particles can be removed via normal iron metabolic pathways. These nanoparticles are also attractive for industrial separations and catalysis because they can be magnetically recovered. However, the size, morphology, and surface coating of the iron oxide nanoparticles greatly affect their magnetic properties and biocompatibility. Therefore, nanoparticles with tunable characteristics are desirable. This chapter elaborates the synthesis techniques for the formation of iron oxide nanoparticles with good control over reproducibility, surface and magnetic properties, and morphology. The well-known co-precipitation and thermal decomposition methods are detailed in this chapter. The surface modification routes and characterization of these nanoparticles are also discussed. The chapter will be particularly useful for engineering/science graduate students and/or faculty interested in synthesizing iron oxide nanoparticles for specific research applications.

Synthesis, characterization, and aqueous self-assembly of octenylsuccinate Oat β-glucan

Amphiphilic oat β-glucan derivatives carrying octenylsuccinic groups as hydrophobic moieties have been synthesized. Materials with a different degree of substitution (DS) and weight-average molecular weight (Mw) for oat β-glucan were prepared and characterized using elemental analysis, infrared (IR) spectroscopy, and high performance size exclusion chromatography (HPSEC). Dynamic light scattering (DLS), fluorescence spectroscopy, and transmission electron microscopy (TEM) revealed that octenylsuccinate oat β-glucan (OSG) can self-assemble into spherical micelles in water with an average size ranging from 175 to 600 nm. OSG micelles were negatively charged as indicated by ζ-potential measurement. The critical micelle concentration (CMC) of OSGs varied from 0.206 to 0.039 mg/mL, depending on the DS and Mw of the oat β-glucan. It was found that the presence of OSG micelles in aqueous solution could significantly enhance the solubility of curcumin by 880 fold. Thus, OSG might have great potential in applications as hydrophobic nutrient delivery carriers.

Emerging technologies: polymer-free phospholipid encapsulated sirolimus nanocarriers for the controlled release of drug from a stent-plus-balloon or a stand-alone balloon catheter

Drug-eluting stents have proven to be effective in reducing the risk of late restenosis. In order to achieve a controlled and prolonged release of the antiproliferative agent, current drug-eluting stents utilise various biodegradable as well as non-erodible polymeric blends to coat the stent surface and to serve as drug carriers. The utilisation of polymeric compounds in current drug-eluting stents may eventually limit their performance as well as their clinical applicability due to the potential induction of undesirable local reactions. The development of alternative, polymer-free drug carriers has the potential to overcome some of the limitations of current drug-eluting stent formulations. Moreover, improvements in drug carriers may also result in an expansion of the technological possibilities for other intravascular drug delivery systems, such as metal-free or even implant-free solutions. This article describes the structure and the preclinical validation profile of a novel phospholipid encapsulated sirolimus nanocarrier, used as a coating in two formulations: a coronary stent-plus-balloon system and a stand-alone balloon catheter. The nanoparticles provided a stable, even and homogenous coating to the devices in both formulations. Dose-finding studies allowed the most appropriate identification of the best nanoparticle structure associated with an extremely efficient transfer of drug to all layers of the vessel wall, achieving high tissue concentrations that persisted days after the application, with low systemic drug leaks.

Tetraiodothyroacetic acid-conjugated PLGA nanoparticles: a nanomedicine approach to treat drug-resistant breast cancer

AIM

The aim was to evaluate tetraiodothyroacetic acid (tetrac), a thyroid hormone analog of L-thyroxin, conjugated to poly(lactic-co-glycolic acid) nanoparticles (T-PLGA-NPs) both in vitro and in vivo for the treatment of drug-resistant breast cancer.

MATERIALS & METHODS

The uptake of tetrac and T-PLGA-NPs in doxorubicin-resistant MCF7 (MCF7-Dx) cells was evaluated using confocal microscopy. Cell proliferation assays and a chick chorioallantoic membrane model of FGF2-induced angiogenesis were used to evaluate the anticancer effects of T-PLGA-NPs. In vivo efficacy was examined in a MCF7-Dx orthotopic tumor BALBc nude mouse model.

RESULTS

T-PLGA-NPs were restricted from entering into the cell nucleus, and T-PLGA-NPs inhibited angiogenesis by 100% compared with 60% by free tetrac. T-PLGA-NPs enhanced inhibition of tumor-cell proliferation at a low-dose equivalent of free tetrac. In vivo treatment with either tetrac or T-PLGA-NPs resulted in a three- to five-fold inhibition of tumor weight.

CONCLUSION

T-PLGA-NPs have high potential as anticancer agents, with possible applications in the treatment of drug-resistant cancer.

Controlled block copolymer micelle formation for encapsulation of hydrophobic ingredients

We report on the formation of polymeric micelles in water using triblock copolymers with a polyethylene glycol middle block and various hydrophobic outer blocks prepared with the precipitation method. We form micelles in a reproducible manner with a narrow size distribution. This suggests that during the formation of the micelles the system had time to form micelles under close-to-thermodynamic control. This may explain why it is possible to use an equilibrium self-consistent field theory to predict the hydrodynamic size and the loading capacity of the micelles in accordance with experimental finding. Yet, the micelles are structurally quenched as concluded from the observation of size stability in time. We demonstrate that our approach enables to prepare rather hydrophobic block copolymer micelles with tunable size and loading.

BSA-PLGA-based core-shell nanoparticles as carrier system for water-soluble drugs

PURPOSE

Preparation, optimization and in vitro evaluation of core-shell nanoparticles comprising of a hydrophilic core of BSA surrounded by a hydrophobic shell of PLGA for loading water-soluble drugs.

METHODS

A double emulsion method was optimized for preparation of BSA-PLGA based core-shell nanoparticles. Proof of concept for core-shell type structure was established by visual techniques like confocal microscopy and TEM. Characterization was done for particle size, encapsulation efficiency, drug loading and in vitro drug release. Cellular uptake was assessed using confocal microscopy, bio-TEM and HPLC assay, and cytotoxic activity was tested by MTT assay in MG-63 osteosarcoma cells.

RESULTS

The optimized core-shell nanoparticles showed a particle size of 243 nm (PDI-0.13) and encapsulation efficiency of 40.5% with a drug loading of 8.5% w/w. In vitro drug release studies showed a sustained release for 12 h. Cellular uptake studies indicated a rapid and efficient uptake within 2 h. TEM studies indicated that the core-shell nanoparticles were localized in cytoplasm region of the cells. Gemcitabine loaded core-shell nanoparticles showed enhanced cytotoxicity against MG-63 cells as compared to marketed formulation of gemcitabine (GEMCITE®).

CONCLUSION

These results indicate that core-shell nanoparticles can be a good carrier system for delivering hydrophilic drugs like gemcitabine successfully to the cells with enhanced efficacy.

Engineering dextran-based scaffolds for drug delivery and tissue repair

Owing to its chemically reactive hydroxyl groups, dextran can be modified with different functional groups to form spherical, tubular and 3D network structures. The development of novel functional scaffolds for efficient controlled release and tissue regeneration has been a major research interest, and offers promising therapeutics for many diseases. Dextran-based scaffolds are naturally biodegradable and can serve as bioactive carriers for many protein biomolecules. The reconstruction of the in vitro microenvironment with proper signaling cues for large-scale tissue regenerative scaffolds has yet to be fully developed, and remains a significant challenge in regenerative medicine. This paper will describe recent advances in dextran-based polymers and scaffolds for controlled release and tissue engineering. Special attention is given to the development of dextran-based hydrogels that are precisely manipulated with desired structural properties and encapsulated with defined angiogenic growth factors for therapeutic neovascularization, as well as their potential for wound repair.

Thiolated chitosan-modified PLA-PCL-TPGS nanoparticles for oral chemotherapy of lung cancer

Oral chemotherapy is a key step towards 'chemotherapy at home', a dream of cancer patients, which will radically change the clinical practice of chemotherapy and greatly improve the quality of life of the patients. In this research, three types of nanoparticle formulation from commercial PCL and self-synthesized d-α-tocopheryl polyethylene glycol 1000 succinate (PLA-PCL-TPGS) random copolymer were prepared in this research for oral delivery of antitumor agents, including thiolated chitosan-modified PCL nanoparticles, unmodified PLA-PCL-TPGS nanoparticles, and thiolated chitosan-modified PLA-PCL-TPGS nanoparticles. Firstly, the PLA-PCL-TPGS random copolymer was synthesized and characterized. Thiolated chitosan greatly increases its mucoadhesiveness and permeation properties, thus increasing the chances of nanoparticle uptake by the gastrointestinal mucosa and improving drug absorption. The PLA-PCL-TPGS nanoparticles were found by FESEM that they are of spherical shape and around 200 nm in diameter. The surface charge of PLA-PCL-TPGS nanoparticles was reversed from anionic to cationic after thiolated chitosan modification. The thiolated chitosan-modified PLA-PCL-TPGS nanoparticles have significantly higher level of the cell uptake than that of thiolated chitosan-modified PLGA nanoparticles and unmodified PLA-PCL-TPGS nanoparticles. In vitro cell viability studies showed advantages of the thiolated chitosan-modified PLA-PCL-TPGS nanoparticles over Taxol® in terms of cytotoxicity against A549 cells. It seems that the mucoadhesive nanoparticles can increase paclitaxel transport by opening tight junctions and bypassing the efflux pump of P-glycoprotein. In conclusion, PLA-PCL-TPGS nanoparticles modified by thiolated chitosan could enhance the cellular uptake and cytotoxicity, which revealed a potential application for oral chemotherapy of lung cancer.

Colloidal gold-loaded, biodegradable, polymer-based stavudine nanoparticle uptake by macrophages: an in vitro study

OBJECTIVE

We describe the development, evaluation, and comparison of colloidal gold-loaded, poly(d,l-lactic-co-glycolic acid)-based nanoparticles containing anti-acquired immunodeficiency syndrome drug stavudine and uptake of these nanoparticles by macrophages in vitro.

METHODS

WE USED THE FOLLOWING METHODS IN THIS STUDY: drug-excipient interaction by Fourier transform infrared spectroscopy, morphology of nanoparticles by field-emission scanning electron microscopy, particle size by a particle size analyzer, and zeta potential and polydispersity index by a zetasizer. Drug loading and in vitro release were evaluated for formulations. The best formulation was incorporated with fluorescein isothiocyanate. Macrophage uptake of fluorescein isothiocyanate nanoparticles was studied in vitro.

RESULTS

Variations in process parameters, such as speed of homogenization and amount of excipients, affected drug loading and the polydispersity index. We found that the drug was released for a prolonged period (over 63 days) from the nanoparticles, and observed cellular uptake of stavudine nanoparticles by macrophages.

CONCLUSION

Experimental nanoparticles represent an interesting carrier system for the transport of stavudine to macrophages, providing reduced required drug dose and improved drug delivery to macrophages over an extended period. The presence of colloidal gold in the particles decreased the drug content and resulted in comparatively faster drug release.

Alginic acid nanoparticles prepared through counterion complexation method as a drug delivery system

In this paper, a kind of novel alginic acid nanoparticles was successfully prepared by a non-solvent-aided counterion complexation between anionic alginic acid and cationic 2,2'-(ethylenedioxy)diethylamine in aqueous solution followed by cross-linking alginic acid moiety using Ca(2+). It was found that these alginic acid nanoparticles have a spherical morphology with the diameter of about 100 nm, and negatively charged surface with the zeta potential of about -30 mV. Compared to the desintegrity of un-cross-linked nanoparticles, the Ca(2+)-cross-linked nanoparticles maintained their integrity in the aqueous medium with the physiological pH value. Doxorubicin, a model antitumor drug, was successfully loaded into the alginic acid nanoparticles, and their in vitro and in vivo antitumor activities were evaluated. It was found that these negatively charged nanoparticles could be taken up by the cancer cells through an endocytosis mechanism. In vivo near-infrared (NIR) fluorescence imaging and biodistribution examinations showed that the alginic acid nanoparticles could be well-accumulated in the tumor site by the enhanced permeability and retention effect. In vivo antitumor examination showed that the drug-loaded nanoparticles have superior efficacy in impeding tumor growth and prolonging the lifetime of H22 tumor-bearing mice than free drug.

In vitro and in vivo antitumor activity of doxorubicin-loaded alginic-acid-based nanoparticles

The antitumor activities of DOX-loaded alginic acid/poly[2-(diethylamino)ethyl methacrylate] (ALG-PDEA) nanoparticles are evaluated both in vitro and in vivo. TEM imaging shows that the ALG-PDEA NPs have a spherical morphology with a size of about 120 nm. CLSM observations reveal that the negatively charged ALG-PDEA NPs can be taken up well by cells. In vivo NIR fluorescence imaging shows that the ALG-PDEA NPs can passively target the tumor area because of the EPR effect in the H22 tumor-bearing mouse. In vivo antitumor efficacy examinations indicate that DOX-loaded ALG-PDEA NPs have significantly superior efficacy in impeding tumor growth compared to free DOX and low toxicity to living mice.

Biodegradable nanoparticles mimicking platelet binding as a targeted and controlled drug delivery system

This research aims to develop targeted nanoparticles as drug carriers to the injured arterial wall under fluid shear stress by mimicking the natural binding ability of platelets via interactions of glycoprotein Ib-alpha (GPIbα) of platelets with P-selectin of damaged endothelial cells (ECs) and/or with von Willebrand factor (vWF) of the subendothelium. Drug-loaded poly(d,l-lactic-co-glycolic acid) (PLGA) nanoparticles were formulated using a standard emulsion method and conjugated with glycocalicin, the external fraction of platelet GPIbα, via carbodiimide chemistry. Surface-coated and cellular uptake studies in ECs showed that conjugation of PLGA nanoparticles, with GPIb, significantly increased nanoparticle adhesion to P-selectin- and vWF-coated surfaces as well as nanoparticle uptake by activated ECs under fluid shear stresses. In addition, effects of nanoparticle size and shear stress on adhesion efficiency were characterized through parallel flow chamber studies. The observed decrease in bound nanoparticle density with increased particle sizes and shear stresses is also explained through a computational model. Our results demonstrate that the GPIb-conjugated PLGA nanoparticles can be used as a targeted and controlled drug delivery system under flow conditions at the site of vascular injury.

Oral Delivery of DMAB-Modified Docetaxel-Loaded PLGA-TPGS Nanoparticles for Cancer Chemotherapy

Three types of nanoparticle formulation from biodegradable PLGA-TPGS random copolymer were developed in this research for oral administration of anticancer drugs, which include DMAB-modified PLGA nanoparticles, unmodified PLGA-TPGS nanoparticles and DMAB-modified PLGA-TPGS nanoparticles. Firstly, the PLGA-TPGS random copolymer was synthesized and characterized. DMAB was used to increase retention time at the cell surface, thus increasing the chances of particle uptake and improving oral drug bioavailability. Nanoparticles were found to be of spherical shape with an average particle diameter of around 250 nm. The surface charge of PLGA-TPGS nanoparticles was changed to positive after DMAB modification. The results also showed that the DMAB-modified PLGA-TPGS nanoparticles have significantly higher level of the cellular uptake than that of DMAB-modified PLGA nanoparticles and unmodified PLGA-TPGS nanoparticles. In vitro, cytotoxicity experiment showed advantages of the DMAB-modified PLGA-TPGS nanoparticle formulation over commercial Taxotere(®) in terms of cytotoxicity against MCF-7 cells. In conclusion, oral chemotherapy by DMAB-modified PLGA-TPGS nanoparticle formulation is an attractive and promising treatment option for patients.

Magnetic nanoparticles for targeted vascular delivery

Magnetic targeting has shown promise to improve the efficacy and safety of different classes of therapeutic agents by enabling their active guidance to the site of disease and minimizing dissemination to nontarget tissues. However, its translation into clinic has proven difficult because of inherent limitations of traditional approaches inapplicable for deep tissue targeting in human subjects and a need for developing well-characterized and fully biocompatible magnetic carrier formulations. A novel magnetic targeting scheme based on the magnetizing effect of deep-penetrating uniform fields is presented as an example of a strategy providing a potentially clinically viable solution for preventing injury-triggered reobstruction of stented blood vessels (in-stent restenosis). The design of optimized magnetic carrier formulations and experimental results showing the feasibility of uniform field-controlled targeting for site-specific vascular delivery of small-molecule pharmaceuticals, biotherapeutics, and cells are discussed in the context of antirestenotic therapy. The versatility of this approach applicable to different classes of therapeutic agents exerting their antirestenotic effects through distinct mechanisms prompts exploring the utility of uniform field-mediated magnetic stent targeting for combination therapies with enhanced efficiencies and improved safety profiles. Additional improvements in terms of site specificity and protracted carrier retention at the site of injury may be expected from the development and use of magnetic carriers exhibiting affinity for arterial wall-specific antigens.

Polylactide-co-glycolide nanoparticles for controlled delivery of anticancer agents

The effectiveness of anticancer agents may be hindered by low solubility in water, poor permeability, and high efflux from cells. Nanomaterials have been used to enable drug delivery with lower toxicity to healthy cells and enhanced drug delivery to tumor cells. Different nanoparticles have been developed using different polymers with or without surface modification to target tumor cells both passively and/or actively. Polylactide-co-glycolide (PLGA), a biodegradable polyester approved for human use, has been used extensively. Here we report on recent developments concerning PLGA nanoparticles prepared for cancer treatment. We review the methods used for the preparation and characterization of PLGA nanoparticles and their applications in the delivery of a number of active agents. Increasing experience in the field of preparation, characterization, and in vivo application of PLGA nanoparticles has provided the necessary momentum for promising future use of these agents in cancer treatment, with higher efficacy and fewer side effects.

Streptokinase loading in liposomes for vascular targeted nanomedicine applications: encapsulation efficiency and effects of processing

Vascular diseases leading to thrombo-occlusion are the leading cause of morbidity and mortality worldwide. Revascularization and restoration of antegrade blood flow is critical for tissue survival and patient health. In this aspect, systemic administration of thrombolytics (e.g., streptokinase) to dissolve occlusive thrombi is a clinically established strategy. However, this strategy typically necessitates the administration of large doses, leading to a high incidence of hemorrhagic complications due to systemic side effects. To minimize this risk, liposomes specifically targeted to the site of thrombo-occlusion have been bioengineered by exploiting ligand-receptor relationships pertinent to thrombus-associated cell phenotypes. This study focuses on encapsulating streptokinase within these liposomes, specifically regarding the effect of liposome processing conditions on streptokinase encapsulation and activity. Theoretical calculations of encapsulation capacity agreed well with that reported in the literature. The experimental encapsulation efficiency values are 45.9 ± 34.0% (n = 9 ± SD) and 21.6 ± 30.0% (n = 6 ± SD), using two different methods. The liposome processing conditions are found to decrease streptokinase activity; however, over 30% remain active after processing, maintaining enough activity to be therapeutic especially when protected inside a vehicle targeted to the site of thrombo-occlusion. The insight gained from the research reported here would enable refining the design and the processing conditions of liposomal formulations of fibrinolytics to yield reduced variability in encapsulation efficiency and streptokinase activity. The design of a thrombus-targeted 'stealth' liposome reported earlier and the current findings of fibrinolytics' encapsulation and activity in such liposomes can be efficiently integrated to develop an efficient strategy for vascular nanomedicine.

Shear-regulated uptake of nanoparticles by endothelial cells and development of endothelial-targeting nanoparticles

The purpose of this research project was to develop nanoparticles with improved targeting, adhesion, and cellular uptake to activated or inflamed endothelial cells (ECs) under physiological flow conditions. Our hypothesis is that by mimicking platelet binding to activated ECs through the interaction between platelet glycoprotein Ibalpha (GP Ibalpha) and P-selectin on activated endothelial cells, GP Ibalpha-conjugated nanoparticles could exhibit increased targeting and higher cellular uptake in injured or activated endothelial cells under physiological flow conditions. To test this hypothesis, fluorescent-carboxylated polystyrene nanoparticles were selected for the study as a model particle because of its narrow size distribution as a "proof-of-concept." Using confocal microscopy, fluorescent measurements, and protein assays, cellular uptake properties were characterized for these polystyrene nanoparticles. The study also found that conjugation of 100-nm polystyrene nanoparticles with glycocalicin (the extracellular segment of GP Ibalpha) significantly increased the particle adhesion on P-selectin-coated surfaces and cellular uptake of nanoparticles by activated endothelial cells under physiological flow conditions. The results demonstrate that these novel endothelial-targeting nanoparticles could be the first step toward developing a targeted and sustained drug delivery system that can improve shear-regulated particle adhesion and cellular uptake.

Cationic surface modification of PLG nanoparticles offers sustained gene delivery to pulmonary epithelial cells

Biodegradable polymeric nanoparticles are currently being explored as a nonviral gene delivery system; however, many obstacles impede the translation of these nanomaterials. For example, nanoparticles delivered systemically are inherently prone to adsorbing serum proteins and agglomerating as a result of their large surface/volume ratio. What is desired is a simple procedure to prepare nanoparticles that may be delivered locally and exhibit minimal toxicity while improving entry into cells for effectively delivering DNA. The objective of this study was to optimize the formulation of poly(D,L-lactide-co-glycolide) (PLG) nanoparticles for gene delivery performance to a model of the pulmonary epithelium. Using a simple solvent diffusion technique, the chemistry of the particle surface was varied by using different coating materials that adsorb to the particle surface during formation. A variety of cationic coating materials were studied and compared to more conventional surfactants used for PLG nanoparticle fabrication. Nanoparticles (approximately 200 nm) efficiently encapsulated plasmids encoding for luciferase (80-90%) and slowly released the same for 2 weeks. In A549 alveolar lung epithelial cells, high levels of gene expression appeared at day 5 for certain positively charged PLG particles and gene expression was maintained for at least 2 weeks. In contrast, PEI gene expression ended at day 5. PLG particles were also significantly less cytotoxic than PEI suggesting the use of these vehicles for localized, sustained gene delivery to the pulmonary epithelium.