Self-assembled nanomicelles using PLGA-PEG amphiphilic block copolymer for insulin delivery: a physicochemical investigation and determination of CMC values

Concepts and Approaches to Reduce or Avoid Protein Corona Formation on Nanoparticles: Challenges and Opportunities

This review describes the formation of a protein corona (or its absence) on different classes of nanoparticles, its basic principles, and its consequences for nanomedicine. For this purpose, it describes general concepts to control (guide/minimize) the interaction between artificial nanoparticles and plasma proteins to reduce protein corona formation. Thereafter, methods for the qualitative or quantitative determination of protein corona formation are presented, as well as the properties of nanoparticle surfaces, which are relevant for protein corona prevention (or formation). Thereby especially the role of grafting density of hydrophilic polymers on the surface of the nanoparticle is discussed to prevent the formation of a protein corona. In this context also the potential of detergents (surfactants) for a temporary modification as well as grafting-to and grafting-from approaches for a permanent modification of the surface are discussed. The review concludes by highlighting several promising avenues. This includes (i) the use of nanoparticles without protein corona for active targeting, (ii) the use of synthetic nanoparticles without protein corona formation to address the immune system, (iii) the recollection of nanoparticles with a defined protein corona after in vivo application to sample the blood proteome and (iv) further concepts to reduce protein corona formation.

Advanced Technologies of Drug Delivery to the Posterior Eye Segment Targeting Angiogenesis and Ocular Cancer

Retinoblastoma (RB), a childhood retinal cancer is caused due to RB1 gene mutation which affects the child below 5 years of age. Angiogenesis has been proven its role in RB metastasis due to the presence of vascular endothelial growth factor (VEGF) in RB cells. Therefore, exploring angiogenic pathway by inhibiting VEGF in treating RB would pave the way for future treatment. In preclinical studies, anti-VEGF molecule have shown their efficacy in treating RB. However, treatment requires recurrent intra-vitreal injections causing various side effects along with patient nonadherence. As a result, delivery of anti-VEGF agent to retina requires an ocular delivery system that can transport it in a non-invasive manner to achieve patient compliance. Moreover, development of these type of systems are challenging due to the complicated physiological barriers of eye. Adopting a non-invasive or minimally invasive approach for delivery of anti-VEGF agents would not only address the bioavailability issues but also improve patient adherence to therapy overcoming the side effects associated with invasive approach. The present review focuses on the eye cancer, angiogenesis and various novel ocular drug delivery systems that can facilitate inhibition of VEGF in the posterior eye segment by overcoming the eye barriers.

Optimization of PLGA-DSPE hybrid nano-micelles with enhanced hydrophobic capacity for curcumin delivery

Poly (D, L Lactic-co-Glycolic acid) (PLGA) is an FDA-approved polymer. It is distinguished from other biocompatible polymers by its feasibility of production and safety for intravenous cancer tumor targeting. Curcumin (CUR) is a natural molecule with versatile bioactivities including inhibiting the nuclear Factor kappa B (Nf-kB) levels in cancer cells, increased by chemotherapy agents. Our group previously reported a successful decrease in the p65 (RelA) subunit of Nf-kB using 125 µg/ml CUR loaded into PLGA nano-micelles. However, this amount was insufficient to reduce all Nf-kB subunits. This study aimed to increase the hydrophobic capacity of PLGA toward CUR using 1,2-Distearoyl-sn-glycerol-3-phosphoethanolamine (DSPE), an FDA-approved phospholipid. PLGA-DSPE hybrid nano-micelles (HNM) were prepared using two different methods, oil-in-water (OiWa) and film preparation-rehydration (FiRe). The encapsulated CUR was successfully increased to 250 µg/ml using the FiRe method. Physicochemical characterization of CUR-loaded HNM was performed using DLS FT-IR, DSC, and HPLC. In HNM with a size of 156.6 nm, DSPE, incorporated with all functional groups of PLGA, and CUR was trapped in the core of this structure. The release profile of CUR was suitable for targeted cancer therapy and the Encapsulation Efficacy was 92%.

Dapsone-Loaded Mixed Micellar Gel for Treatment OF Acne Vulgaris

Mixed polymeric micelles are potential nanocarriers for topical drug delivery. Dapsone (DAP) is an antibacterial used as anti-acne agent, but challenged by low water solubility and poor skin permeability. In the present study, DAP-loaded mixed micellar gel was developed comprising Pluronics F-68 and F-127. Micelles were prepared by solvent evaporation method and particle size, ex vivo permeation, drug loading, and entrapment efficiency were determined. Central Composite Design was used to optimize formulation. Independent variables were concentration of Pluronics at three levels while micelle size and drug loading capacities were dependent variables. Droplet size ranged from 400 to 500 nm. Transmission electron microscopy revealed spherical morphology of micelles. Optimized micelles were incorporated into gel base using HPMC K100M, Sodium CMC, and Carbopol 980 as gelling agents. Gels were evaluated for pH, drug content, spreadability, rheology, syneresis, ex vivo permeation, and subacute dermal toxicity. Compared with solubility of free DAP (0.24+0.056 µg/ml), solubility in mixed micelles was 18.42±3.4 µg/ml in water at room temperature. Order of spreadability of gels was Na CMC < HPMC < Carbopol 980. Carbopol gels displayed thixotropy with index of 3.17. Syneresis for all gels from day 0 to day 30 was found to be in range of 4.2 to 15.6% w/w. Subacute dermal toxicity studies showed no signs of erythema and edema on rat skin until 21 days. These results suggest that mixed micelles can significantly increase solubility and permeability and sustain release of DAP and are suitable carriers for topical DAP delivery in anti-acne therapies.

Caffeic Acid Phenethyl Ester Loaded PEG-PLGA Nanoparticles Enhance Wound Healing in Diabetic Rats

Delayed wound healing is a serious complication of diabetes and a main reason for foot amputation. Caffeic acid phenethyl ester (CAPE) is a main active constituent of honeybee propolis with reported appealing pharmacological activities. In the current study, CAPE was loaded onto PEG-PLGA nanoparticles and showed a particle size of 198 ± 7.3 nm and polydispersity index of 0.43 ± 0.04. An in vivo study was performed to appraise the wound-healing activity of CAPE-loaded PEG-PLGA nanoparticles (CAPE-NPs) in diabetic rats. Wound closure was significantly accelerated in rats treated with CAPE-NPs. This was confirmed via histological examinations of skin tissues that indicated expedited healing and enhanced collagen deposition. This was accompanied by observed antioxidant activity as evidenced by the prevention of lipid peroxidation and the exhaustion of superoxide dismutase (SOD) and catalase (CAT) activities. In addition, CAPE-NPs showed superior anti-inflammatory activity as compared with the regular formula of CAPE, as they prevented the expression of interleukin-6 (IL-6) as well as tumor necrosis-alpha (TNF-α). The pro-collagen actions of CAPE-NPs were highlighted by the enhanced hyroxyproline content and up-regulation of Col 1A1 mRNA expression. Furthermore, the immunohistochemial assessment of skin tissues indicated that CAPE-NPs enhance proliferation and angiogenesis, as shown by the increased expression of transforming growth factor β1 (TGF-β1) and platelet-derived growth factor subunit B (PDGF-B). In conclusion, CAPE-loaded PEG-PLGA nanoparticles possess potent healing effects in diabetic wounds. This is mediated, at least partially, by its antioxidant, anti-inflammatory, and pro-collagen as well as angiogenic activities.

Synthesis, physicochemical characterization, and in vitro evaluation of biodegradable PLGA nanoparticles entrapped to folic acid for targeted delivery of kaempferitrin

Polymeric nanoparticles are widely studied in the treatment of colorectal cancer. Kaempferitrin-loaded nontoxic and biodegradable poly(d,l-lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) developed by the solvent emulsion evaporation method by improving its solubility and bioavailability. In order to improve the delivery of kaempferitrin (KM) to cancerous cells, folic acid (FA) combined kaempfertrin PLGA NPs were prepared. The goal of the study was whether PLGA NPs with surface KM and FA could help to prevent colorectal cancer. The synthesis of KM with FA in a nanomedicine could be crucial in the development of colon cancer chemotherapeutics. The physicochemical characteristics of synthesized KM-entrapped PLGA NPs were investigated by XRD, FTIR, zeta potential, and TEM. The KM + FA + PLGA NPs showed particle size with 132.9 ± 1.4 nm, zeta potential -15.0 ± 1.73 mV, encapsulation efficiency 67.92 ± 4.8, and drug-loading capacity 0.463 ± 0.173. In vitro cytotoxicity study on HT-29 cell lines using the MTT assay, the apoptotic study revealed that KM + FA + PLGA NPs have an enhanced cytotoxic effect compared to the KM + PLGA NPs drug solution. These findings suggested that KM + FA + PLGA NPs could be an effective chemotherapeutic drug delivery system in colon adenocarcinoma HT-29 cells.

Biodegradable and Light-Responsive Polymeric Nanoparticles for Environmentally Safe Herbicide Delivery

The low utilization efficiency of pesticides exerts an adverse impact on the environment and human health. Polymer-related controlled-release nanosized pesticide systems provide a promising and efficient way to overcome the problem. In this work, a biodegradable and light-responsive amphiphilic polymer was synthesized via 1,1,3,3-tetramethylguanidine-promoted polyesterification under mild conditions (low temperature, no vacuum, and no inert gas protection). We used this polymer to fabricate a light-triggered controlled-release nanosized pesticide system. The herbicide, 2,4-dichlorophenoxyacetic acid (2,4-D), was selected as a model drug to show its potential as a controlled-release pesticide system. It was found that the 2,4-D-loaded polymeric nanoparticles were stable without the treatment of UV, while the release rate of 2,4-D from the nanoparticles gradually increased after treatment with UV light. Pot trial showed that the 2,4-D-loaded polymer nanoparticles showed a good herbicidal effect. Finally, toxicity studies suggested that the polymer can reduce toxicity to nontarget organisms.

Amitriptyline-Based Biodegradable PEG-PLGA Self-Assembled Nanoparticles Accelerate Cutaneous Wound Healing in Diabetic Rats

The aim of this work was to study the healing activity of amitriptyline (Amitrip) in rat diabetic wounds. A nanoformula of the drug was prepared as Amitrip-based biodegradable PEG-PLGA self-assembled nanoparticles (Amitrip-NPs) with a mean particle size of 67.4 nm. An in vivo investigation was conducted to evaluate the wound-healing process of Amitrip-NPs in streptozotocin-induced diabetic rats. Wound contraction was accelerated in rats treated with Amitrip-NPs. Histological examinations confirmed these findings, with expedited remodeling and collagen deposition in the NPs-treated animals. The formula showed anti-inflammatory activities as demonstrated by inhibition of interleukin-6 (IL-6) expression and tumor necrosis factor-α (TNF-α) expression, as well as enhanced expression of interleukin-10 (IL-10). In addition, Amitrip-NPs protected against malondialdehyde (MDA) buildup and superoxide dismutase (SOD) and glutathione peroxidase (GPx) enzymatic exhaustion. The pro-collagen activity of Amitrip-NPs was confirmed by the observed enhancement of hydroxyproline wounded skin content, upregulation of Col 1A1 mRNA expression and immune expression of collagen type IV expression. Further, Amitrip-NPs significantly increased expression transforming growth factor-β1 (TGF-β1), vascular endothelial growth factor-A (VEGF-A), platelet-derived growth factor-B (PDGF-B) and cluster of differentiation 31 (CD31). In conclusion, the developed Amitrip-NPs expedited wound healing in diabetic rats. This involves anti-inflammatory, antioxidant, pro-collagen and angiogenic activities of the prepared NPs. This opens the gate for evaluating the usefulness of other structurally related tricyclic antidepressants in diabetic wounds.

CD44/Folate Dual Targeting Receptor Reductive Response PLGA-Based Micelles for Cancer Therapy

In this study, a novel poly (lactic-co-glycolic acid) (PLGA)-based micelle was synthesized, which could improve the therapeutic effect of the antitumor drug doxorubicin hydrochloride (DOX) and reduce its toxic and side effects. The efficient delivery of DOX was achieved by active targeting mediated by double receptors and stimulating the reduction potential in tumor cells. FA-HA-SS-PLGA polymer was synthesized by amidation reaction, and then DOX-loaded micelles were prepared by dialysis method. The corresponding surface method was used to optimize the experimental design. DOX/FA-HA-SS-PLGA micelles with high drug loading rate and encapsulation efficiency were prepared. The results of hydrophilic experiment, critical micelle concentration determination, and hemolysis test all showed that DOX/FA-HA-SS-PLGA micelles had good physicochemical properties and biocompatibility. In addition, both in vitro reduction stimulus response experiment and in vitro release experiment showed that DOX/FA-HA-SS-PLGA micelles had reduction sensitivity. Molecular docking experiments showed that it can bind to the target protein. More importantly, in vitro cytology studies, human breast cancer cells (MCF-7), human non-small cell lung cancer cells (A549), and mouse colon cancer cells (CT26) were used to demonstrate that the dual receptor-mediated endocytosis pathway resulted in stronger cytotoxicity to tumor cells and more significant apoptosis. In and in vivo antitumor experiment, tumor-bearing nude mice were used to further confirm that the micelles with double targeting ligands had better antitumor effect and lower toxicity. These experimental results showed that DOX/FA-HA-SS-PLGA micelles have the potential to be used as chemotherapeutic drugs for precise tumor treatment.

Oral insulin delivery by epithelium microenvironment-adaptive nanoparticles

Oral protein drug delivery using nano-based systems remains challenging, as contradictory surface properties are required for efficient navigation through the intestinal mucus and epithelium barriers. Therefore, new nanoplatforms with tunable surface properties in vivo are urgently needed. Inspired by the slightly acidic microclimate of the jejunal epithelial surface, we report a novel epithelium microenvironment-adaptive nanoplatform that undergoes a hydrophilicity-hydrophobicity transition at the epithelial surface. First, we synthesized and characterized a biodegradable copolymer consisting of PEG and PLGA building blocks linked by a hydrazone bond (PLGA-Hyd-PEG) to fabricate the pH-sensitive core-shell architecture of an oral insulin system. Then we loaded the system as a freeze-dried powder into enteric-coated capsules. PLGA-Hyd-PEG nanoparticles showed excellent drug protection and rapid mucus penetration owing to the high stability of the PEG coating in jejunal fluid. In the acidic microenvironment of the jejunal epithelial surface (pH ~5.5), PEG was rapidly cleaved and the hydrazone bond was hydrolyzed, converting the nanoparticle surface from hydrophilic to hydrophobic, thereby facilitating internalization into cells. Pharmacodynamic studies showed that PLGA-Hyd-PEG nanoparticles resulted in significant decrease in blood glucose level after intrajejunal administration in both normal and diabetic rats relative to control nanoparticles. In addition, enteric-coated capsules containing PLGA-Hyd-PEG nanoparticles reduced blood glucose by 35% for up to 10 h after oral administration to diabetic rats. Our findings provide a new strategy for regulating the surface properties of nanoparticles for efficient oral drug delivery.

An overview of PLGA in-situ forming implants based on solvent exchange technique: effect of formulation components and characterization

As a result of the low oral bioavailability of several drugs, there is a renewed interest for parenteral administration to target their absorption directly into the blood bypassing the long gastrointestinal route and hepatic metabolism. In order to address the potential side effects of frequent injections, sustained release systems are the most popular approaches for achieving controlled long-acting drug delivery. Injectable in-situ forming implants (ISFIs) have gained greater popularity in comparison to other sustained systems. Their significant positive aspects are attributed to easier production, acceptable administration route, reduced dosing frequency and patient compliance achievement. ISFI systems, comprising biodegradable polymers such as poly (lactide-co-glycolide) (PLGA) based on solvent exchange mechanisms, are emerged as liquid formulations that develop solid or semisolid depots after injection and deliver drugs over extended periods. The drug release from ISFI systems is generally characterized by an initial burst during the matrix solidification, followed by diffusion processes and finally polymeric degradation and erosion. The choice of suitable solvent with satisfactory viscosity, miscibility and biocompatibility along with considerable PLGA hydrophobicity and molecular weights is fundamental for optimizing the drug release. This overview gives a particular emphasis on evaluations and the wide ranges of requirements needed to achieve reasonable physicochemical characteristics of ISFIs.

Targeted and oxygen-enriched polymeric micelles for enhancing photodynamic therapy

Photodynamic therapy (PDT) has been emerged as an alternative therapeutic modality in treatment of several malignant tumors. However, the therapeutic efficacy of PDT is often limited by the solubility of photosensitizers, tumor hypoxia and lack of target specificity to cancer cells. In this study, we developed a folate-conjugated fluorinated polymeric micelle (PFFA) to deliver the hydrophobic photosensitizer (chlorin e6, Ce6) to overcome these limitations. The fluorinated micelles exhibit the low critical micelle concentration, good long-term stability, higher oxygen-carrying capacity and better singlet oxygen generation efficiency compared to non-fluorinated micelles, indicating the potential to improve the PDT efficacy in hypoxic conditions. Cytotoxicity of PDT effect and cellular uptake demonstrate the higher cell growth inhibition to HeLa cells upon irradiation attributed to the selective internalization of Ce6-loaded PFFA micelles (PFFA-Ce6). All results demonstrate the PFFA-Ce6 micelles with targeting function and oxygen-carrying capacity can serve as a promising drug delivery system for hydrophobic photosensitizers and improvement on PDT efficacy.

Multifunctional polymeric micellar nanomedicine in the diagnosis and treatment of cancer

Polymeric micelles are a prevalent topic of research for the past decade, especially concerning their fitting ability to deliver drug and diagnostic agents. This delivery system offers outstanding advantages, such as biocompatibility, high loading efficiency, water-solubility, and good stability in biological fluids, to name a few. The multifunctional polymeric micellar architect offers the added capability to adapt its surface to meet the looked-for clinical needs. This review cross-talks the recent reports, proof-of-concept studies, patents, and clinical trials that utilize polymeric micellar family architectures concerning cancer targeted delivery of anticancer drugs, gene therapeutics, and diagnostic agents. The manuscript also expounds on the underlying opportunities, allied challenges, and ways to resolve their bench-to-bedside translation for allied clinical applications.

Optimization and Characterization of Brimonidine Tartrate Nanoparticles-loaded In Situ Gel for the Treatment of Glaucoma

Purposes: The present study aimed to develop brimonidine tartrate loaded poly(lactic-co-glycolic acid) acid vitamin E-tocopheryl polyethylene glycol 1000 succinate (BRT-PLGA-TPGS) nanoparticles in thermosensitivein situ gel to improve mucoadhensive properties and drug holding capacity for the better management of glaucoma.Methods: Nanoparticles was optimized by means of Box-Behnken Design (BBD). The formulations were prepared using various concentration of PLGA (0.1-0.4% w/v) and TPGS (0.3-0.5% w/v). The analytical data of fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and transmission electron microscopy (TEM) depicted the drug excipients compatibility and confirmed the nanoparticles. Nanoparticles incorporated gel was evaluated for transcorneal permeability, gelation time, gelling temperature, and rheological studies. In addition, in vitro, transcorneal permeation drug release studies and intraocular pressure (IOP) for optimized gel was also performed. Biocompatibility of formulations was investigated in rabbit model.Results: The drug loaded nanoparticles exhibited 115.72 ± 4.18 nm, 0.190 ± 0.02, -11.80 ± 2.24 mV and 74.85 ± 6.54% of mean size, polydispersity index (PDI), zeta potential and entrapment efficiency (% EE), respectively. As compared to marketed eye drop, the sustained and continuous release BRT release from Poloxamer-based in situ gel was 85.31 ± 3.51% till 24 h. The transcorneal steady-state flux (136.32 μg cm^-2 h^-1) of optimized in situ gel was approximately 3.5 times higher than marketed formulation (38.60 μg cm^-2 h^-1) flux at 4 h. The optimized formulation produces 3 fold greater influences on percentage reduction of IOP (34.46 ± 4.21%) than the marketed formulation (12.24 ± 2.90%) till 8 h.Conclusion: The incorporation of optimized BRT-PLGA-TPGS nanoparticles into a thermosensitivein situ gel matrix to improve precorneal residence time without causing eye irritation and also serve the sustained release of BRT through cornea for effective management of glaucoma.

Development and In Vitro Evaluation of 2-Methoxyestradiol Loaded Polymeric Micelles for Enhancing Anticancer Activities in Prostate Cancer

The present study aimed to formulate and optimize 2ME-loaded PMs (2ME-PMs) for enhancing the anticancer activity of 2ME in prostate cancer (PC). The 2ME-PMs were formulated using PEG-PLGA (PL), Tween 80 (TW80), and alpha-lipoic acid (ALA). The optimization was carried out using a Box-Behnken design with the PL, TW80, and ALA as the independent variables and particle size (PS) as the response. The formulation was optimized for the lowest possible PS, and the software suggested optimum formula with 100.282 mg, 2%, and 40 mg for PL, TW80, and ALA, respectively. The optimized PMs had spherical morphology with PS of 65.36 ± 2.2 nm, polydispersity index (PDI) of 0.273 ± 0.03, and entrapment efficiency of 65.23 ± 3.5%. The in vitro drug release was 76.3 ± 3.2% after 24 h. The cell line studies using PC-3 cells showed IC50 values of 18.75 and 54.41 µmol for 2ME-PM and 2ME, respectively. The estimation of tumor biomarkers was also carried out. The tumor biomarkers caspase-9 (17.38 ± 1.42 ng/mL), tumor protein P53 (p53) (1050.0 ± 40.9 pg/mL), nitric oxide (NO) (0.693 ± 0.03 pg/mL), interleukin-1β (IL-1β) (25.84 ± 2.23 pg/mL), nuclear factor kappa B (NF-kB) (0.719 ± 0.07 pg/mL), interleukin-6 (IL-6) (2.53 ± 0.16 folds), and cyclooxygenase-2 (COX-2) (3.04 ± 0.5 folds) were determined for 2ME-PMs and the results showed that these values changed significantly compared to those of 2ME. Overall, the results showed that the formulation of 2ME to 2ME-PMs enhances the anticancer effect. The exploration of the combined advantages of PEG, PLGA, ALA, and PMs in cancer therapy and the delivery of 2ME is the major importance of this research work. PEG reduces the elimination of 2ME, PLGA enhances 2ME loading, ALA has an inherent apoptotic effect, and PMs can efficiently target tumor cells.

Phenylboronic acid-functionalized F127-oligochitosan conjugate micelles for doxorubicin encapsulation

Doxorubicin shows good anticancer activity, but poor pharmacokinetic property and high organ toxicity restrict its clinical application. The synthesized phenylboronic acid-modified F127-chitosan conjugate was used to prepare doxorubicin-loaded micelles through dialysis method. The physicochemical properties of the doxorubicin-loaded micelles were characterized. These micelles were further evaluated for in vitro release/cytotoxicity, in vivo activity/biosafety, and pharmacokinetic studies. in vitro release experiment demonstrated that the release of doxorubicin from drug-loaded micelles was pH-dependent. in vitro cytotoxic study showed that the introduction of phenylboronic acid resulted in lower IC₅₀ against B16 cells than that in non-modified F127-chitosan micelles group, and the doxorubicin-loaded micelles displayed lower in vitro activity against B16, A549, and HT-29 cells than free doxorubicin did. However, in vivo experiments confirmed that the doxorubicin-loaded micelles were safe for mouse main organs, obviously improved pharmacokinetic parameters of doxorubicin in rat and achieved comparable inhibition of tumor growth with no animal death in B16-bearing mice models throughout the experiment when compared with free doxorubicin. The phenylboronic acid-sialic acid interaction and pH-sensitive drug release might play important roles in increased tumor targeting and therapeutic effect of the doxorubicin-loaded micelles.

Unexpected conformational behavior of poly(poly(ethylene glycol) methacrylate)-poly(propylene carbonate)-poly(poly(ethylene glycol) methacrylate) (PPEGMA-PPC-PPEGMA) amphiphilic block copolymers in micellar solution and at the air-water interface

HYPOTHESIS

This paper investigates the self-assembly behavior of a new amphiphilic block copolymer, PPEGMA-PPC-PPEGMA, in dilute aqueous solution and at the air-water interface. In PPEGMA-PPC-PPEGMA, the hydrophilic PEG moieties exist as side chains attached to the PMA backbone. Because of this unique non-linear architecture, the morphological and conformational properties of self-assembled PPEGMA-PPC-PPEGMA polymers are expected to be different from those of conventional linear PEG-based polymer surfactants.

EXPERIMENTS

For this study, three PPEGMA-PPC-PPEGMA samples having an identical PPC molecular weight (5.6 kDa) and different PPEGMA molecular weights (7.2, 2.8 and 2.1 kDa on either side) (named "G7C6G7", "G3C5G3", and "G2C6G2", respectively) were synthesized. The micellar self-assembly behaviors of these materials were investigated by cryo-TEM, rheology, DLS, and visual observation. Langmuir monolayers of these materials were characterized by surface mechanical testing.

FINDINGS

PPEGMA-PPC-PPEGMA micelles were found to have a spherical geometry, irrespective of copolymer composition. Interestingly, G2C6G2 and G3C6G3 micelles formed weakly-bound clusters, whereas G7C6G7 micelles predominantly existed as isolated micelles. Detailed analysis suggests that this unexpected trend in micelle morphology originates from the fact that the PPEGMA blocks are only partially hydrated at aqueous interfaces. Detailed features of the surface pressure-area isotherms obtained from Langmuir PPEG-PPC-PPEGMA monolayers further supported this notion.

Recent Progress in the Development of Poly(lactic-co-glycolic acid)-Based Nanostructures for Cancer Imaging and Therapy

Diverse nanosystems for use in cancer imaging and therapy have been designed and their clinical applications have been assessed. Among a variety of materials available to fabricate nanosystems, poly(lactic-co-glycolic acid) (PLGA) has been widely used due to its biocompatibility and biodegradability. In order to provide tumor-targeting and diagnostic properties, PLGA or PLGA nanoparticles (NPs) can be modified with other functional materials. Hydrophobic or hydrophilic therapeutic cargos can be placed in the internal space or adsorbed onto the surface of PLGA NPs. Protocols for the fabrication of PLGA-based NPs for cancer imaging and therapy are already well established. Moreover, the biocompatibility and biodegradability of PLGA may elevate its feasibility for clinical application in injection formulations. Size-controlled NP’s properties and ligand–receptor interactions may provide passive and active tumor-targeting abilities, respectively, after intravenous administration. Additionally, the introduction of several imaging modalities to PLGA-based NPs can enable drug delivery guided by in vivo imaging. Versatile platform technology of PLGA-based NPs can be applied to the delivery of small chemicals, peptides, proteins, and nucleic acids for use in cancer therapy. This review describes recent findings and insights into the development of tumor-targeted PLGA-based NPs for use of cancer imaging and therapy.

Promises of Nanotherapeutics in Obesity

The application of nanotechnology to medicine promises a wide range of new tools and possibilities, from earlier diagnostics and improved imaging, to better, more efficient, and more targeted therapies. This emerging field could help address obesity, with advances in drug delivery, nutraceuticals, and genetic and epigenetic therapeutics. Its application to obesity is still largely in the development phase. Here, we review the novel angle of nanotech applied to human consumable products and their specific applications to addressing obesity through nutraceuticals, with respect to benefits and limitations of current nanotechnology methods. Further, we review potential future applications to deliver genetic and epigenetic miRNA therapeutics. Finally, we discuss future directions, including theranostics, combinatory therapy, and personalized medicine.

Self-Assembling Hybrid Linear-Dendritic Block Copolymers: The Design of Nano-Carriers for Lipophilic Antitumoral Drugs

Two series of amphiphilic block copolymers with a hybrid linear-dendritic structure are presented. The compounds consisted of a hydrophilic poly (ethylene glycol) (PEG) block and a 2,2'-bis(hydroxymethyl)propionic acid (bis-MPA) dendron functionalized with stearic acid chains that impart a hydrophobic nature to the block. Different self-assembled nanostructures with a hydrophobic interior and a hydrophilic external part were obtained depending on the length of the PEG chain (Mn = 2000 and Mn = 5000) and the generation of the bis-MPA dendron. The materials were characterized by transmission electron microscopy (TEM). The shapes of the aggregates ranged from spherical or cylindrical micelles to flexible bilayers. The hydrophobic core enabled these nanostructures to encapsulate the water-insoluble drug plitidepsin. The efficacy of these new plitidepsin-containing carriers was evaluated in four cancer cell-lines and they showed similar anticancer activity to the current standard drug formulation.

Molecular Self-Assembly Strategy for Encapsulation of an Amphipathic α-Helical Antimicrobial Peptide into the Different Polymeric and Copolymeric Nanoparticles

Encapsulation of peptide and protein-based drugs in polymeric nanoparticles is one of the fundamental fields in controlled-release drug delivery systems. The molecular mechanisms of absorption of peptides to the polymeric nanoparticles are still unknown, and there is no precise molecular data on the encapsulation process of peptide and protein-based drugs. Herein, the self-assembly of different polymers and block copolymers with combinations of the various molecular weight of blocks and the effects of resultant polymer and copolymer nanomicelles on the stability of magainin2, an α-helical antimicrobial peptide, were investigated by means of all-atom molecular dynamics (MD) simulation. The micelle forming, morphology of micellar aggregations and changes in the first hydration shell of the micelles during micelles formation were explored as well. The results showed that the peptide binds to the polymer and copolymer micelles and never detaches during the MD simulation time. In general, all polymers and copolymers simultaneously encapsulated the peptide during micelles formation and had the ability to maintain the helical structure of the peptide, whereas the first hydration shell of the peptide remained unchanged. Among the micelles, the polyethylene glycol (PEG) micelles completely encapsulated magainin2 and, surprisingly, the NMR structure of the peptide was perfectly kept during the encapsulation process. The MD results also indicated that the aromatic and basic residues of the peptide strongly interact with polymers/copolymers and play important roles in the encapsulation mechanism. This research will provide a good opportunity in the design of polymer surfaces for drug delivery applications such as controlled-release peptide delivery systems.

Novel Brassinosteroid-Modified Polyethylene Glycol Micelles for Controlled Release of Agrochemicals

Two synthetic analogues of brassinosteroids (DI31 and S7) exhibit good plant growth enhancer activity. However, their hydrophobicity and quick metabolism in plants have limited their application and benefits in agriculture. Our objective was to prepare novel brassinosteroid-modified polyethylene glycol (PEG) micelles to achieve controlled release with extended stability while retaining agrochemical activity. Spectroscopic studies confirmed quantitative disubstitution of studied PEGs with the brassinosteroids, while elemental analysis assessed purity of the synthesized conjugates. Conjugates were also characterized by X-ray diffraction and thermal analysis. Dynamic and static light scattering showed stable and homogeneous approximately spherical micelles with average hydrodynamic diameters of 22-120 nm and almost neutral ζ potential. Spherical 30-140 nm micelles were observed by electron microscopy. Sustained in vitro releases at pH 5.5 were extended up to 96 h. Prepared PEG micelles showed good agrochemical activity in the radish seed bioassay and no cytotoxicity to the human microvascular endothelial cell line in the MTS test.

Nanocarrier fabrication and macromolecule drug delivery: challenges and opportunities

Macromolecules (proteins/peptides) have the potential for the development of new therapeutics. Due to their specific mechanism of action, macromolecules can be administered at relatively low doses compared with small-molecule drugs. Unfortunately, the therapeutic potential and clinical application of macromolecules is hampered by various obstacles including their large size, short in vivo half-life, phagocytic clearance, poor membrane permeability and structural instability. These challenges have encouraged researchers to develop novel strategies for effective delivery of macromolecules. In this review, various routes of macromolecule administration (invasive/noninvasive) are discussed. The advantages/limitations of novel delivery systems and the potential role of nanotechnology for the delivery of macromolecules are elaborated. In addition, fabrication approaches to make nanoformulations in different shapes and sizes are also summarized.

Self-Assembled PAEEP-PLLA Micelles with Varied Hydrophilic Block Lengths for Tumor Cell Targeting

The properties of hydrophilic shell in micelles significantly affect the interaction between micelles and cells. Compared with frequently used polyethylene glycol (PEG) as the hydrophilic block, polyphosphoesters (PPEs) are superior in functionality, biocompatibility, and degradability. A series of amphiphilic poly(aminoethyl ethylene phosphate)/poly(l-lactide acid) (PAEEP-PLLA) copolymers were synthesized with hydrophilic PAEEP with different chain lengths. The corresponding self-assembled micelles were used for doxorubicin (Dox) entrapment. The length of hydrophilic PAEEP block on the shell affected the structure of micelles. PAEEPm-PLLA168 (m = 130 or 37) polymers formed vesicles, while PAEEPm-PLLA168 (m = 15 or 9) formed large compound micelles (LCMs), suggesting a difference in tumor cell uptake and intracellular trafficking. PAEEP15-PLLA168 polymer showed superiority on cellular uptake amount, intracellular drug release, and cell apoptosis. Lipid rafts and macropinocytosis are the leading endocytic pathways of PAEEP-PLLA micelles. The shape coupling between micelles and cell membrane facilitated cell surface features such as flattened protrusions (membrane protein) and inward-pointing hollows as well as efficient endocytosis. These results suggested that PAEEP-PLLA self-assembled block copolymer micelles may be an excellent drug delivery system for tumor treatment and that the hydrophilic chain length could regulate drug targeting to tumor cells.

Targeting of the kynurenic acid across the blood-brain barrier by core-shell nanoparticles

Core-shell nanoparticles (CSNPs) were developed to get over therapeutic amount of kynurenic acid (KYNA) across the blood-brain barrier (BBB). Bovine serum albumin (BSA) was used as core for encapsulation of KYNA and the BSA/KYNA composite was finally encapsulated by poly(allylamine) hydrochloride (PAH) polymer as shell. In the interest of the optimization of the synthesis the BSA and KYNA interaction was studied by two-dimensional surface plasmon resonance (SPR) technique as well. The average size of d~100 nm was proven by dynamic light scattering (DLS) and transmission electron microscopy (TEM), while the structure of the composites was characterized by fluorescence (FL) and circular dichroism (CD) spectroscopy. The in vitro release properties of KYNA were investigated by a vertical diffusion cell at 25.0 °C and 37.5 °C and the kinetic of the release were discussed. The penetration capacity of the NPs into the central nervous system (CNS) was tested by an in vitro BBB model. The results demonstrated that the encapsulated KYNA had significantly higher permeability compared to free KYNA molecules. In the neurobiological serial of in vivo experiments the effects of peripherally administered KYNA with CSNPs were studied in comparison with untreated KYNA. These results clearly proved that KYNA in the CSNPs, administrated peripherally is suitable to cross the BBB and to induce electrophysiological effects within the CNS. As the neuroprotective properties of KYNA nowadays are proven, the importance of the results is obvious.

Nanocarriers for photodynamic therapy-rational formulation design and medium-scale manufacture

The development and manufacture of novel nanocarriers for drug delivery has proved challenging with regards to scale-up and pharmaceutical quality. Polymeric nanocarriers composed of poly(lactic-co-glycolic acid)-b-poly(ethylene glycol) (PLGA-PEG) were prepared and the photosensitizer meso-tetrakis(3-hydroxyphenyl) chlorin (mTHPC) was effectively encapsulated. Furthermore, the interplay of various process and formulation parameters and their impact on the most important product specifications were investigated by using a factorial design and a central composite design in a microfluidic manufacturing process. These nanoparticles for intravenous administration with a size of 97 ± 0.13 nm, narrow size distribution, and an encapsulation efficiency of more than 80% were produced at high throughput. In vitro stability and in vitro drug release testing were applied for quality control purposes. Finally, the toxicity of the photosensitizer was tested in vitro. The cytotoxicity was successfully reduced while the efficacy of the formulation was maintained. First observations using in vivo imaging suggest effective distribution of the nanocarrier system after injection into rodents. Thus, further in vivo testing of the beneficial effects of nanoencapsulation into the matrix system and its formulation will be considered for the delivery of mTHPC to tumor tissues during photodynamic therapy.

General considerations regarding the in vitro and in vivo properties of block copolymer micelle products and their evaluation

Block copolymer micelles are nanoparticles formed from block copolymers that comprise a hydrophilic polymer such as poly(ethylene glycol) and a poorly soluble polymer such as poly(amino acids). The design of block copolymer micelles is intended to regulate the in vivo pharmacokinetics, stability, and distribution profiles of an entrapped or block copolymer-linked active substance. Several block copolymer micelle products are currently undergoing clinical development; however, a major challenge in the development and evaluation of such products is identification of the physicochemical properties that affect the properties of the drug product in vivo. Here we review the overall in vitro and in vivo characteristics of block copolymer micelle products with a focus on the products currently under clinical investigation. We present examples of methods suitable for the evaluation of the physicochemical properties, non-clinical pharmacokinetics, and safety of block copolymer micelle products.

Synthesis and characterization of cationic polymeric nanoparticles as simvastatin carriers for enhancing the osteogenesis of bone marrow mesenchymal stem cells

Simvastatin (SIM) can increase osteoblast activity and enhance osteogenesis. However, some limitations of SIM have been noted, such as statin-associated rhabdomyolysis and its poor solubility in water. In this study, we fabricated new cationic nanoparticles (NPs) designed for the controlled release of hydrophobic SIM and endocytosis by cells with the aim of reducing the total required amount of SIM administered and enhancing the osteogenesis of bone marrow mesenchymal stem cells (BMSCs). New copolymers of bis(poly(lactic-co-glycolic acid)-phenylalanine-polyethylene glycol)-quaternary ammonium grafted diethyltriamine (bis(PLGA-phe-PEG)-qDETA; BPPD) were created using a diethyltriamine-quaternary ammonium (qDETA) moiety, hetero-bifunctional polyethylene glycol (COOH-PEG-NH2), phenylalanine (phe) and poly(lactic-co-glycolic acid) (PLGA). SIM encapsulated in BPPD NPs (SIM/BPPD) was fabricated using a water-miscible solvent. The size distributions of BPPD NPs and SIM/BPPD NPs, the encapsulation efficacy and the in vitro release profile of SIM in SIM/BPPD NPs over 6days were investigated. Based on the results of Alizarin Red S staining, alkaline phosphatase (ALP) activity assays and quantitative polymerase chain reaction (Q-PCR) results, we propose that SIM/BPPD NPs may induce osteogenesis in BMSCs by enhancing the expression of an osteogenic gene, which subsequently elevates ALP activity and mineralization, resulting in enhanced BMSC osteogenesis. These results suggest that the SIM/BPPD NPs may be used as hydrophobic drug carriers to reduce the total required amount of SIM administered and to provide an effective SIM release mechanism for enhancing BMSC osteogenesis. Surprisingly, BPPD NPs were also shown to have the ability to promote osteogenesis in BMSCs by enhancing the expression of osteogenic genes, especially osteocalcin (OC), and subsequently elevating ALP activity and mineralization.