Amphiphilic block copolymers-based mixed micelles for noninvasive drug delivery

Design, Synthesis, and Comparison of PLA-PEG-PLA and PEG-PLA-PEG Copolymers for Curcumin Delivery to Cancer Cells

Curcumin (CUR) has potent anticancer activities, and its bioformulations, including biodegradable polymers, are increasingly able to improve CUR's solubility, stability, and delivery to cancer cells. In this study, copolymers comprising poly (L-lactide)-poly (ethylene glycol)-poly (L-lactide) (PLA-PEG-PLA) and poly (ethylene glycol)-poly (L-lactide)-poly (ethylene glycol) (PEG-PLA-PEG) were designed and synthesized to assess and compare their CUR-delivery capacity and inhibitory potency on MCF-7 breast cancer cells. Molecular dynamics simulations and free energy analysis indicated that PLA-PEG-PLA has a higher propensity to interact with the cell membrane and more negative free energy, suggesting it is the better carrier for cell membrane penetration. To characterize the copolymer synthesis, Fourier transform-infrared (FT-IR) and proton nuclear magnetic resonance (¹H-NMR) were employed, copolymer size was measured using dynamic light scattering (DLS), and their surface charge was determined by zeta potential analysis. Characterization indicated that the ring-opening polymerization (ROP) reaction was optimal for synthesizing high-quality polymers. Microspheres comprising the copolymers were then synthesized successfully. Of the two formulations, PLA-PEG-PLA experimentally exhibited better results, with an initial burst release of 17.5%, followed by a slow, constant release of the encapsulated drug up to 80%. PLA-PEG-PLA-CUR showed a significant increase in cell death in MCF-7 cancer cells (IC₅₀ = 23.01 ± 0.85 µM) based on the MTT assay. These data were consistent with gene expression studies of Bax, Bcl2, and hTERT, which showed that PLA-PEG-PLA-CUR induced apoptosis more efficiently in these cells. Through the integration of nano-informatics and in vitro approaches, our study determined that PLA-PEG-PLA-CUR is an optimal system for delivering curcumin to inhibit cancer cells.

Ultrasound-responsive hyaluronic acid hydrogel of hydrocortisone to treat osteoarthritis

One of the practical ways to manage the disease flares of arthritis is using an intra-articular depot formulation of glucocorticoids. Hydrogels, as controllable drug delivery systems, are hydrophilic polymers with distinctive properties, such as remarkable water capacity and biocompatibility. This study aimed to design an injectable thermo-ultrasound-triggered drug carrier based on Pluronic® F-127, hyaluronic acid, and gelatin. The in situ hydrogel loaded by hydrocortison was developed and D-optimal design was used to formulate the process. The optimized hydrogel was combined with four different surfactants to better regulate the release rate. In situ gels composed of the hydrocortisone-loaded hydrogel and hydrocortisone-loaded mixed-micelle hydrogel were characterized. The hydrocortisone-loaded hydrogel and selected hydrocortisone-loaded mixed-micelle hydrogel showed a spherical shape and were nano-sized with a unique thermo-responsive nature able to prolong drug release. The ultrasound-triggered release study showed that drug release was time-dependent. By inducing osteoarthritis in a rat model, behavioral tests and histopathological analyses were carried out on the hydrocortisone-loaded hydrogel and a particular hydrocortisone-loaded mixed-micelle hydrogel. In vivo results showed that the selected hydrocortisone-loaded mixed-micelle hydrogel improved the status of the disease. Results highlighted the potential of ultrasound-responsive in situ-forming hydrogels as hopeful formulas for efficient treatment of arthritis.

Engineering the Structure and Rheological Properties of P407 Hydrogels via Reverse Poloxamer Addition

Aqueous solutions of poloxamer 407 (P407), a commercially available and nontoxic ABA triblock polymer (PEO-PPO-PEO), undergo a solution-to-gel transition with increasing temperature and are promising candidates for injectable therapeutics. The gel transition temperature, modulus, and structure are all dictated by polymer concentration, preventing independent tuning of these properties. Here, we show that addition of BAB reverse poloxamers (RPs) to P407-based solutions dramatically alters the gelation temperature, modulus, and morphology. Gelation temperature and RP localization within the hydrogel are dictated by RP solubility. Highly soluble RPs increase gelation temperature and incorporate primarily into the micelle corona regions. Alternatively, RPs with low aqueous solubility decrease gelation temperature and associate within the micelle core and core-corona interface. These differences in RP localization have significant implications for the hydrogel modulus and microstructure. The ability to tune gelation temperature, modulus, and structure through RP addition allows for the design of thermoresponsive materials with specific properties that are unobtainable with neat P407-based hydrogels.

Novel Monomethoxy Poly(Ethylene Glycol) Modified Hydroxylated Tung Oil for Drug Delivery

Novel monomethoxy poly(ethylene glycol) (mPEG) modified hydroxylated tung oil (HTO), denoted as mPEG-HTO-mPEG, was designed and synthesized for drug delivery. mPEG-HTO-mPEG consists of a hydroxylated tung oil center joined by two mPEG blocks via a urethane linkage. The properties of mPEG-HTO-mPEG were affected by the length of the mPEG chain. Three mPEG with different molecular weights were used to prepare mPEG-HTO-mPEG. The obtained three mPEG-HTO-mPEG polymers were characterized by nuclear magnetic resonance (NMR), Fourier transformation infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and gel permeation chromatography (GPC), respectively. Furthermore, the particle sizes of mPEG-HTO-mPEG micelles were evaluated by dynamic light scattering (DLS) and transmission electron microscope (TEM). A critical aggregation concentration (CAC) ranged from 7.28 to 11.73 mg/L depending on the chain length of mPEG. The drug loading and release behaviors of mPEG-HTO-mPEG were investigated using prednisone acetate as a model drug, and results indicated that hydrophobic prednisone acetate could be effectively loaded into mPEG-HTO-mPEG micelles and exhibited a long-term sustained release. Moreover, compared with HTO, mPEG-HTO-mPEG had no obvious cytotoxicity to HeLa and L929 cells. Therefore, monomethoxy poly(ethylene glycol) modified hydroxylated tung oil mPEG-HTO-mPEG may be a promising drug carrier.

New Advances in Biomedical Application of Polymeric Micelles

In the last decade, nanomedicine has arisen as an emergent area of medicine, which studies nanometric systems, namely polymeric micelles (PMs), that increase the solubility and the stability of the encapsulated drugs. Furthermore, their application in dermal drug delivery is also relevant. PMs present unique characteristics because of their unique core-shell architecture. They are colloidal dispersions of amphiphilic compounds, which self-assemble in an aqueous medium, giving a structure-type core-shell, with a hydrophobic core (that can encapsulate hydrophobic drugs), and a hydrophilic shell, which works as a stabilizing agent. These features offer PMs adequate steric protection and determine their hydrophilicity, charge, length, and surface density properties. Furthermore, due to their small size, PMs can be absorbed by the intestinal mucosa with the drug, and they transport the drug in the bloodstream until the therapeutic target. Moreover, PMs improve the pharmacokinetic profile of the encapsulated drug, present high load capacity, and are synthesized by a reproducible, easy, and low-cost method. In silico approaches have been explored to improve the physicochemical properties of PMs. Based on this, a computer-aided strategy was developed and validated to enable the delivery of poorly soluble drugs and established critical physicochemical parameters to maximize drug loading, formulation stability, and tumor exposure. Poly(2-oxazoline) (POx)-based PMs display unprecedented high loading concerning water-insoluble drugs and over 60 drugs have been incorporated in POx PMs. Among various stimuli, pH and temperature are the most widely studied for enhanced drug release at the site of action. Researchers are focusing on dual (pH and temperature) responsive PMs for controlled and improved drug release at the site of action. These dual responsive systems are mainly evaluated for cancer therapy as certain malignancies can cause a slight increase in temperature and a decrease in the extracellular pH around the tumor site. This review is a compilation of updated therapeutic applications of PMs, such as PMs that are based on Pluronics^®, micelleplexes and Pox-based PMs in several biomedical applications.

Targeted delivery of quercetin by biotinylated mixed micelles for non-small cell lung cancer treatment

Lung cancer is the leading cause of cancer death world-wide and its treatment remains a challenge in clinic, especially for non-small cell lung cancer (NSCLC). Thus, more effective therapeutic strategies are required for NSCLC treatment. Quercetin (Que) as a natural flavonoid compound has gained increasing interests due to its anticancer activity. However, poor water solubility, low bioavailability, short half-life, and weak tumor accumulation hinder in vivo applications and antitumor effects of Que. In this study, we developed Que-loaded mixed micelles (Que-MMICs) assembled from 1,2-distearoyl-sn-glycero-3-phosphoethanolamine–poly(ethylene glycol)–biotin (DSPE–PEG–biotin) and poly(ethylene glycol) methyl ether methacrylate–poly[2-(dimethylamino) ethyl acrylate]–polycaprolactone (PEGMA–PDMAEA–PCL) for NSCLC treatment. The results showed that Que was efficiently encapsulated into the mixed micelles and the encapsulation efficiency (EE) was up to 85.7%. Cellular uptake results showed that biotin conjugation significantly improved 1.2-fold internalization of the carrier compared to that of non-targeted mixed micelles. In vitro results demonstrated that Que-MMICs could improve cytotoxicity (IC₅₀ = 7.83 μg/mL) than Que-MICs (16.15 μg/mL) and free Que (44.22 μg/mL) to A549 cells, which efficiently induced apoptosis and arrested cell cycle. Furthermore, Que-MMICs showed satisfactory tumor targeting capability and antitumor efficacy possibly due to the combination of enhanced permeability and retention (EPR) and active targeting effect. Collectively, Que-MMICs demonstrated high accumulation at tumor site and exhibited superior anticancer activity in NSCLC bearing mice model.

Unusual Growth and Hydration Characteristics of Oil Solubilized Micelles in Aqueous Pluronic Systems

Lipophile induced modulations of self-assembly characteristics in aqueous Pluronic systems merit attention because of wide-ranging uses of Pluronics as solubilizing agents of lipophilic substances. In this paper, we report unusual evolutions of structural and hydration properties in lavender essential oil (LO) solubilized Pluronic P85 aqueous micellar systems as a function of micellar volume fraction and temperature. Our DLS, SANS, and viscometry studies show that the spherical-to-wormlike micellar structural transition observed in 1% P85 solutions upon solubilization of LO quite unexpectedly gets suppressed with increased P85 concentration to ≥5%. Detailed SANS studies reveal that the core sizes of the oil solubilized micelles cannot attain the threshold value required for the onset of structural transition at higher copolymer concentrations due to their progressive shrinking with an increase in P85 concentration. Oil solubilized P85 solutions show two cloud points and very interestingly exhibit micellar growth upon cooling to their lower cloud points. Steady state fluorescence studies explain this based on increasing dehydration of micellar corona with a decrease in temperature, very much opposite to what is observed in pure aqueous Pluronic systems. The results give new insight into viscous flow properties and low temperature storage possibilities of oil solubilized aqueous Pluronic systems.

Nature of Saccharide-Induced F127 Micellar Dehydration: An Insight with FDAPT (2-Formyl-5-(4'-N,N-dimethylaminophenyl)thiophene), a Multiparametric Fluorescent Probe

FDAPT (2-formyl-5-(4'-N,N-dimethylaminophenyl)thiophene) is an efficient environment-sensitive fluorescent probe, which senses the alteration of its microenvironment with six different fluorescent parameters, namely, emission intensity, wavelength, fluorescence anisotropy, and corresponding three time-dependent parameters fluorescence lifetime, time-resolved emission spectrum, and anisotropy decay. In the present work, the nature of saccharide-induced dehydration of a F127 polymeric micelle is investigated in detail with FDAPT emission. Using a multiparametric fluorescence approach, it is observed that the saccharide molecules not only decrease the critical micellization temperature of the F127 solution but also strongly alter the physical properties inside the micellar structures. The local polarity and fluidity significantly decrease in the saccharide-induced micelle as compared to the normal F127 micelle. The probe solvation dynamics study reveals that the water content in the core as well as corona domain diminishes significantly in the saccharide-induced micelle as compared to the normal micelle. More precisely, dehydration occurs more in the core region than in the corona region. Also, the saccharide-induced dehydration alters the relative size of the core and corona regions. The extent of dehydration varies with different saccharide molecules. It is also found that the dehydration efficiency order is trisaccharide (raffinose) > disaccharide (sucrose) > monosaccharide (glucose and fructose).

Preparation, evaluation and metabolites study in rats of novel amentoflavone-loaded TPGS/soluplus mixed nanomicelles

Amentoflavone (AMF) is a kind of biflavonoids existing in Ginkgo biloba leaves. It has many biological activities, such as antioxidant, anti-inflammatory, anti-bacterial, antiviral, hypoglycemic, anti-tumor and inducing apoptosis. However, its solubility and bioavailability are poor and there are a few studies on it in vivo. In this study, to improve its solubility and bioavailability, the nanomicelles were prepared with TPGS and soluplus as carriers for the first time. The particle size, Zeta potential, encapsulation efficiency, drug loading, stability, cytotoxicity, cellular uptake, and metabolites in rats were studied. Cytotoxicity, cellular uptake, and metabolites in rats of AMF-loaded TPGS/soluplus mixed micelles were compared with those of AMF. As a result, AMF-loaded TPGS/soluplus mixed micelles with a particle size of 67.33 ± 2.01 nm and Zeta potential of -0.84133 ± 0.041405 mV were successfully prepared. The encapsulation efficiency and drug loading of the mixed nanomicelles were 99.18 ± 0.76% and 2.47 ± 0.01%, respectively. The physical and chemical properties of the mixed micelles were stable within 60 d, and the cytotoxicity of the mixed micelles was much greater than that of AMF monomers. Thirty-four kinds of metabolites of AMF were identified in rats. The metabolites were mainly distributed in rat feces. No metabolites were detected in bile and plasma. 14 kinds of metabolites of the mixed micelles in rats were detected, including 11 in feces, 6 in urine, and 3 in plasma, which indicated that the bioavailability of AMF has been improved. And the toxicity to cancer cells was enhanced, which laid a foundation for the development of new drugs.

Reversible Cross-Linked Mixed Micelles for pH Triggered Swelling and Redox Triggered Degradation for Enhanced and Controlled Drug Release

Good stability and controlled drug release are important properties of polymeric micelles for drug delivery. A good candidate for drug delivery must have outstanding stability in a normal physiological environment, followed with low drug leakage and side effects. Moreover, the chemotherapeutic drug in the micellar core should also be quickly and "on-demand" released in the intracellular microenvironment at the tumor site, which is in favor of overcoming multidrug resistance (MDR) effects of tumor cells. In this work, a mixed micelle was prepared by the simple mix of two amphiphilic copolymers, namely PCL-SS-P(PEGMA-co-MAEBA) and PCL-SS-PDMAEMA, in aqueous solution. In the mixed micelle's core-shell structure, PCL blocks were used as the hydrophobic core, while the micellar hydrophilic shell consisted of two blocks, namely P(PEGMA-co-MAEBA) and PDMAEMA. In the micellar shell, PEGMA provided hydrophilicity and stability, while MAEBA introduced the aldehyde sites for reversible crosslinking. Meanwhile, the PDMAEMA blocks were also introduced in the micellar shell for pH-responding protonation and swelling of the micelle. The disulfide bonds between the hydrophobic core and hydrophilic shell had redox sensitive properties. Reversible cross-linked micelles (RCLMs) were obtained by crosslinking the micellar shell with an imine structure. RCLMs showed good stability and excellent ability against extensive dilution by aqueous solution. In addition, the stability in different conditions with various pH values and glutathione (GSH) concentrations was studied. Then, the anticancer drug doxorubicin (DOX) was selected as the model drug to evaluate drug entrapment and release capacity of mixed micelles. The in vitro release profiles indicated that this RCLM had controlled drug release. In the simulated normal physiological environment (pH 7.4), the drug release of the RCLMs was restrained obviously, and the cumulative drug release content was only 25.7 during 72 h. When it came to acidic conditions (pH 5.0), de-crosslinking of the micelles occurred, as well as protonation of PDMAEMA blocks and micellar swelling at the same time, which enhanced the drug release to a large extent (81.4%, 72 h). Moreover, the drug release content was promoted further in the presence of the reductant GSH. In the condition of pH 5.0 with 10 mM GSH, disulfide bonds broke-up between the micelle core and shell, followed by shedding of the shell from the inner core. Then, the micellar disassembly (degradation) happened based on the de-crosslinking and swelling, and the drug release was as high as 95.3%. The MTT assay indicated that the CLSMs showed low cytotoxicity and good biocompatibility against the HepG2 cells. In contrast, the DOX-loaded CLSMs could efficiently restrain the proliferation of tumor cells, and the cell viability after 48 h incubation was just 13.2%, which was close to that of free DOX. This reversible cross-linked mixed micelle with pH/redox responsive behaviors is a potential nanocarrier for chemotherapy.

Pharmacokinetics and brain targeting of trans-resveratrol loaded mixed micelles in rats following intravenous administration

Trans-Resveratrol (T-RES) is a compound with wide therapeutic applications that shows low bioavailability and distribution across blood-brain barrier. The purpose of our study was to develop T-RES loaded mixed micelle (T-RES-MM) for its enhanced systemic availability and targeting to the brain. T-RES-MMs were formulated using Pluronic F-127 (PF-127) and d-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) by using film hydration process. Formulations were characterized for size of particles, zeta potential, drug efficiency of entrapment, drug loading, and hemolytic study. Further in vivo pharmacokinetic and brain distribution study carried out in Sprague Dawley rats. The nano ranged size for drug-loaded mixed micelles was 21.55 ± 2.15 nm for optimized formulation with PF-127:TPGS (4:1). Formulation with maximum drug loading and entrapment efficiency of 8.4 ± 0.37% and 94.37 ± 1.01% respectively were further used for in vivo study. Percent hemolysis by micelles at all concentrations indicates the biocompatibility and safety for administration by i.v. route. The AUC_0-t for T-RES-MM was 460.98 ± 158.99 h*ng/ml while for T-RES it was 276.27 ± 174.05 h*ng/ml. Drug targeting index suggests successful targeting of T-RES to the brain. Overall findings conclude in prepared T-RES-MM exhibit superiority of formulation as compared to T-RES solution.

Facile Fabrication of an Amentoflavone-Loaded Micelle System for Oral Delivery To Improve Bioavailability and Hypoglycemic Effects in KKAy Mice

In order to increase the oral bioavailability and antidiabetic effect of amentoflavone with multimechanisms, an oral micelle system was developed by using a N-vinyl pyrrolidone-maleate-guerbet alcohol monoester polymer for the first time, which was designated as P(NVP-MGAM)/AF. After oral administration, P(NVP-MGAM)/AF enhanced the oral bioavailability of amentoflavone, which was approximately 3.2 times that of amentoflavone solution. The animal study using the KKAy insulin-resistant diabetes mouse model indicated that it regulates the expression and activity of downstream signaling factors and proteins by lowering blood lipids, reducing inflammatory responses and activating the peroxisome proliferator-activated receptor (PPAR) γ signaling pathway and PI3K/Akt signaling pathway. After being made into micelles, it is more effective because of its better absorbability and bioavailability. The results from this study provide a theoretical basis for the clinical application of amentoflavone for diabetes treatment. The oral micelles of P(NVP-MGAM)/AF may become one of the most potent drugs in the treatment of diabetes mellitus, which opens up a new way for the prevention and treatment of diabetes.

Synthesis and Characterization of Phosphorus- and Carborane-Containing Polyoxanorbornene Block Copolymers

Grubbs-catalyzed ring-opening metathesis polymerization (ROMP) of carborane- and phosphonate-containing monomers has been used for the generation of hybrid block copolymers. Molecular weights with Mn of 50,000 g/mol were readily obtained with polydispersity index values, Đ, between 1.03⁻1.08. Reaction of the phospha ester and carborane substituted oxanorbornene block copolymer with trimethylsilyl bromide led to a new polymer with phosphonic acid functionalities. In application studies, the phospha-carborane functionalized block polymer was tested as heat resistance material. Thermal stability was investigated by thermal gravimetric analysis (TGA) and microscale combustion calorimetry (MCC) analysis. Thermal treatment and ceramic yield under air were directly correlated to the carborane content of the block copolymer. However, phosphorus content in the polymer was more crucial for the char residues when heated under nitrogen atmosphere. The peak heat release rate (PHRR) increased as the number of phosphonate functionalities increased. However, corresponding phosphonic acid derivatives featured a lower heat release rate and total heat release. Moreover, the phosphonic acid functionalities of the block copolymer offer efficient chelating capabilities for iron nanoparticles, which is of interest for applications in biomedicine in the future. The complexation with iron oxide nanoparticles was studied by transmission electron microscopy (TEM) and inductively coupled plasma mass spectrometry (ICP⁻MS).

Leukocyte-mimicking Pluronic-lipid nanovesicle hybrids inhibit the growth and metastasis of breast cancer

Breast cancer is a severe threat to the health of women, and the metastasis of tumor cells leads to high mortality in female patients. Evidence shows that leukocytes are recruited by breast tumors through adhesion to inflammatory endothelial cells as well as tumor cells. Moreover, it is known that Pluronic P123 is effective in the reduction of matrix metalloproteinases (MMPs), which play a key role in the degradation of the extracellular matrix (ECM), therefore helping tumor cells to escape from the primary site. Inspired by these mechanisms, we established a leukocyte-mimicking Pluronic-lipid nanovesicle hybrid (LPL) through integrating the membrane proteins extracted from leukocytes with membrane-like vesicles, with Pluronic P123 hybridized in the lipid bilayer, while paclitaxel (PTX) was selected as the model drug. The hybrid vesicles were perfectly incorporated with the leukocyte membrane proteins, and no disruption to the lipid membrane was caused by P123, with the bio-targeting ability of leukocytes and the MMP-9-downregulation effect of P123 fully preserved in LPL. LPL exhibited enhanced cellular uptake and anti-metastasis efficacy in in vitro assays, while significant tumor targeting capabilities were also found through biodistribution assays. Moreover, the in vivo therapeutic effects of PTX-loaded LPL (PTX-LPL) were observed, with an 80.84% inhibition rate of tumor growth and a 10.62% metastatic rate of tumor foci in lung tissue. Furthermore, the amounts of MMP-9 and neutrophils in the tumor as well as in the lung were greatly reduced with PTX-LPL. In summary, LPL may have potential applications in metastatic breast cancer therapy.

Targeted and Synergic Glioblastoma Treatment: Multifunctional Nanoparticles Delivering Verteporfin as Adjuvant Therapy for Temozolomide Chemotherapy

Despite advances in cancer therapies, glioblastoma multiforme treatment remains inefficient due to the brain-blood barrier (BBB) inhibitory activity and to the low temozolomide (TMZ) chemotherapeutic selectivity. To improve therapeutic outcomes, in this work we propose two strategies, (i) photodynamic therapy (PDT) as adjuvant treatment and (ii) engineering of multifunctional theranostic/targeted nanoparticles ( m-NPs) that integrate biotin as a targeting moiety with rhodamine-B as a theranostic agent in pluronic P85/F127 copolymers. These smart m-NPs can surmount the BBB and coencapsulate multiple cargoes under optimized conditions. Overall, the present study conducts a rational m-NP design, characterization, and optimizes the formulation conditions. Confocal microscopy studies on T98-G, U87-MG, and U343 glioblastoma cells and on NIH-3T3 normal fibroblast cells show that the m-NPs and the encapsulated drugs are selectively taken up by tumor cells presenting a broad intracellular distribution. The formulations display no toxicity in the absence of light and are not toxic to healthy cells, but they exert a robust synergic action in cancer cells in the case of concomitant PDT/TMZ treatment, especially at low TMZ concentrations and higher light doses, as demonstrated by nonlinear dose-effect curves based on the Chou-Talalay method. The results evidenced different mechanisms of action related to the disjoint cell cycle phases at the optimal PDT/TMZ ratio. This effect favors synergism between the PDT and the chemotherapy with TMZ, enhances the antiproliferative effect, and overcomes cross-resistance mechanisms. These results point out that m-NP-based PDT adjuvant therapy is a promising strategy to improve TMZ-based glioblastoma multiforme treatments.

CD44 directed nanomicellar payload delivery platform for selective anticancer effect and tumor specific imaging of triple negative breast cancer

Triple negative breast cancer (TNBC) is a highly aggressive tumor subtype, lacking estrogen, progesterone and human epidermal growth factor-2 (HER-2) receptors. Thus, early detection and targeted therapy of TNBC is an urgent need. Herein, we have developed a CD44 targeting Hyaluronic Acid (HA) decorated biocompatible oligomer, containing FDA approved vitamin E TPGS and Styrene Maleic Anhydride (SMA) (HA-SMA-TPGS) for targeting TNBC. The self-assembling HA-SMA-TPGS was encapsulated with poorly water soluble, potent curcumin analogue (CDF) to form nanomicelles (NM), HA-SMA-TPGS-CDF has demonstrated excellent nanoparticle characteristics for parenteral delivery. The targeted NM can selectively kill TNBC cells through CD44 mediated apoptosis pathway. Tumor imaging using phase-2 clinical trial near infrared (NIR)-fluorescent dye (S0456) conjugate, HA-SMA-TPGS-S0456 showed excellent TNBC tumor accumulation with minimum liver and spleen uptake. To our best of knowledge, for the first time, we are reporting a promising platform for CD44 mediated multimodal NIR imaging and cytotoxin delivery to TNBC.

Formulation of Poloxamers for Drug Delivery

Poloxamers, also known as Pluronics®, are block copolymers of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO), which have an amphiphilic character and useful association and adsorption properties emanating from this. Poloxamers find use in many applications that require solubilization or stabilization of compounds and also have notable physiological properties, including low toxicity. Accordingly, poloxamers serve well as excipients for pharmaceuticals. Current challenges facing nanomedicine revolve around the transport of typically water-insoluble drugs throughout the body, followed by targeted delivery. Judicious design of drug delivery systems leads to improved bioavailability, patient compliance and therapeutic outcomes. The rich phase behavior (micelles, hydrogels, lyotropic liquid crystals, etc.) of poloxamers makes them amenable to multiple types of processing and various product forms. In this review, we first present the general solution behavior of poloxamers, focusing on their self-assembly properties. This is followed by a discussion of how the self-assembly properties of poloxamers can be leveraged to encapsulate drugs using an array of processing techniques including direct solubilization, solvent displacement methods, emulsification and preparation of kinetically-frozen nanoparticles. Finally, we conclude with a summary and perspective.

Pharmacokinetics of Quercetin-Loaded Methoxy Poly(ethylene glycol)-b-poly(L-lactic acid) Micelle after Oral Administration in Rats

The purpose of this study was to evaluate the potential of micelle to change the pharmacokinetics of quercetin (QUT), with a primary goal of enhancing its oral bioavailability. QUT-loaded methoxy poly(ethylene glycol)-b-poly(L-lactic acid) micelle (QUT-loaded MPEG-b-PLLA micelle) was prepared by a thin-film hydration method, resulting in a particle size of 88.5 nm. A liquid chromatography tandem-mass spectrometry (LC-MS/MS) method was developed and validated for determination of QUT in rat plasma. The chromatographic separation was performed on an Agilent Eclipse-C₁₈ (4.6 mm × 50 mm, 3.5 μm) with an isocratic mobile phase system consisting of water and methanol (30 : 70, v/v) at a flow rate of 0.4 mL/min. Calibration curves were linear over the concentration ranges of 2.5–2000 ng/mL for QUT. The micelle was orally administered at a single does in rats, and the pharmacokinetic parameters were evaluated and compared with that administered with the QUT aqueous suspension. The results show that the micelle was able to increase the QUT's oral bioavailability 9-fold compared to the QUT aqueous suspension. These results suggest that methoxy poly(ethylene glycol)-b-poly(L-lactic acid) is a potential carrier for the oral delivery of QUT.

Effect of Architecture on Micelle Formation and Liquid-Crystalline Ordering in Solutions of Block Copolymers Comprising Flexible and Rigid Blocks: Rod-Coil vs Y-Shaped vs Comblike Copolymers

Micelle formation of amphiphilic block copolymers of various architectures comprising both flexible and rodlike blocks were studied in a selective solvent via dissipative particle dynamics (DPD) simulations. Peculiarities of self-assembly of Y-shaped (insoluble rigid block and two flexible soluble arms) and comblike (soluble flexible backbone with insoluble rigid side chains) copolymers are compared with those of equivalent rod-coil diblock copolymers. We have shown that aggregation of the rigid blocks into the dense core of the micelles is accompanied by their nematic ordering. However, the orientation order parameter and aggregation number of the micelles are strongly dependent on macromolecular architecture. Relatively small micelles of pretty high nematic order parameter, S₂ ≈ 0.5-0.8, are the features of the Y-shaped and rod-coil copolymer micelles. They are characterized by different responses to the solvent quality worsening. The aggregation number of the rod-coil diblock copolymer micelles increases and that of the Y-shaped copolymer micelles decreases at the solvent quality worsening. However, the order parameter grows in both cases, achieving a maximum value for the Y-shaped copolymer micelles. Herewith, the core elongates. On the contrary, comblike copolymers self-assemble into bigger spherical micelles whose core possesses a lower nematic order of the rods, S₂ ≈ 0.3-0.4. The aggregation number is shown to depend on the length of the combs (on the number of repeating elements in the architecture). Possible physical reasons for such behavior of the systems are discussed.

Thermoresponsive Elastin-b-Collagen-Like Peptide Bioconjugate Nanovesicles for Targeted Drug Delivery to Collagen-Containing Matrices

Over the past few decades, (poly)peptide block copolymers have been widely employed in generating well-defined nanostructures as vehicles for targeted drug delivery applications. We previously reported the assembly of thermoresponsive nanoscale vesicles from an elastin-b-collagen-like peptide (ELP-CLP). The vesicles were observed to dissociate at elevated temperatures, despite the LCST-like behavior of the tethered ELP domain, which is suggested to be triggered by the unfolding of the CLP domain. Here, the potential of using the vesicles as drug delivery vehicles for targeting collagen-containing matrices is evaluated. The sustained release of an encapsulated model drug was achieved over a period of 3 weeks, following which complete release could be triggered via heating. The ELP-CLP vesicles show strong retention on a collagen substrate, presumably through collagen triple helix interactions. Cell viability and proliferation studies using fibroblasts and chondrocytes suggest that the vesicles are highly cytocompatible. Additionally, essentially no activation of a macrophage-like cell line is observed, suggesting that the vesicles do not initiate an inflammatory response. Endowed with thermally controlled delivery, the ability to bind collagen, and excellent cytocompatibility, these ELP-CLP nanovesicles are suggested to have significant potential in the controlled delivery of drugs to collagen-containing matrices and tissues.