Hydrotropic polymer micelle system for delivery of paclitaxel

Boron Neutron Capture Therapy Enhanced by Boronate Ester Polymer Micelles: Synthesis, Stability, and Tumor Inhibition Studies

Boron neutron capture therapy (BNCT) targets invasive, radioresistant cancers but requires a selective and high B-10 loading boron drug. This manuscript investigates boron-rich poly(ethylene glycol)-block-(poly(4-vinylphenyl boronate ester)) polymer micelles synthesized via atom transfer radical polymerization for their potential application in BNCT. Transmission electron microscopy (TEM) revealed spherical micelles with a uniform size of 43 ± 10 nm, ideal for drug delivery. Additionally, probe sonication proved effective in maintaining the micelles' size and morphology postlyophilization and reconstitution. In vitro studies with B16-F10 melanoma cells demonstrated a 38-fold increase in boron accumulation compared to the borophenylalanine drug for BNCT. In vivo studies in a B16-F10 tumor-bearing mouse model confirmed enhanced tumor selectivity and accumulation, with a tumor-to-blood (T/B) ratio of 2.5, surpassing BPA's T/B ratio of 1.8. As a result, mice treated with these micelles experienced a significant delay in tumor growth, highlighting their potential for BNCT and warranting further research.

Innovative strategies for effective paclitaxel delivery: Recent developments and prospects

PURPOSE

Paclitaxel is an effective chemotherapeutic agent against a variety of cancer types. However, the clinical utility of paclitaxel is restricted by its poor solubility in water and high toxicity, resulting in low drug tolerance. These difficulties could be resolved by using suitable pharmacological carriers. Hence, it is essential to determine innovative methods of administering this effective medication to overcome paclitaxel's inherent limitations.

METHODS

An extensive literature search was conducted using multiple electronic databases to identify relevant studies published.

RESULTS

In this comprehensive analysis, many different paclitaxel delivery systems are covered and discussed, such as albumin-bound paclitaxel, polymeric micelles, paclitaxel-loaded liposomes, prodrugs, cyclodextrins, and peptide-taxane conjugates. Moreover, the review also covers various delivery routes of conventional paclitaxel or novel paclitaxel formulations, such as oral administration, local applications, and intraperitoneal delivery.

CONCLUSION

In addition to albumin-bound paclitaxel, polymeric micelles appear to be the most promising formulations for innovative drug delivery systems at present. A variety of variants of polymeric micelles are currently undergoing advanced phases of clinical trials.

A quality by design framework for developing nanocrystal bioenabling formulations

The present study aims to outline a rational framework for the design and development of a 1.0% (w/v) hydrocortisone nanocrystal-based formulation, resorting to a simple, efficient, and scalable nanonization methodology, based on the high-pressure homogenization (HPH) technique. Accordingly, the innovative product was comprehensively optimized following a Quality by Design (QbD) approach. The thorough selection of formulation composition was driven by a dual purpose: improving skin permeation and stability. In the early stage of development, a Failure Mode, Effects and Criticality Analysis (FMECA) diagram was employed to identify the most impactful variables for the critical quality attributes (CQAs). In this sense, a rotatable, three-factor and five-level circumscribed central composite design (CCCD) was applied to investigate how squalene concentration (x1), soluplus concentration (x2) and HPH-time (x3) influence physicochemical properties, performance and physical stability of the formulation. A robust Design Space (DS) was defined, establishing the optimal settings for the critical variables, whose combination meets the requirements set in the quality target product profile (QTPP). Morphological analysis revealed the cuboidal shape of hydrocortisone nanocrystals. In what concerns colloidal properties, the most promising formulation disclosed a small particle size (Dx(50) = 311.8 ± 1.5 nm), along with narrow size distribution (span value = 1.91 ± 0.17). Zeta potential results (-2.19 ± 0.15 mV--12.1 ± 0.4 mV) suggested a steric hindrance stabilization. FTIR spectra showed no chemical interactions between drug and formulation components. XRD diffractograms confirmed loss of crystallinity during the downsizing process. In vitro studies revealed an improvement on drug release rate (316 ± 21-516 ± 35 μg/cm2/√t), compared to the coarse suspension and commercial products, and a straight dependence on the stabilizer concentration and HPH time. The permeation flux across the skin (0.16 ± 0.02-1.2 ± 0.5 μg/cm2/h) appeared to be dependent on the drug physicochemical properties, in particular saturation solubility. Further characterization of the experimental formulations pointed out the role of the stabilizing component to prevent against physical instability phenomena. This organic solvent-free, and therefore "green" nanocrystal production technology offers great potential for pharmaceutical R&D and drug delivery by enabling the development of new forms of conventional drugs with optimal physicochemical properties and performance.

Structural Investigation on How Guest Loading of Poly(2-oxazoline)-Based Micelles Affects the Interaction with Simulated Intestinal Fluids

Drug loading of polymer micelles can have a profound effect on their particle size and morphology as well as their physicochemical properties. In turn, this influences performance in biological environments. For oral delivery of drugs, the intestinal environment is key, and consequently, a thorough structural understanding of what happens at this material-biology interface is required to understand in vivo performance and tailor improved delivery vehicles. In this study, we address this interface in vitro through a detailed structural characterization of the colloidal assemblies of polymeric micelles based on poly(2-oxazolines) with three different guest loadings with the natural product curcumin (17-52 wt %) in fed-state simulated intestinal fluids (FeSSIF). For this, we employ NMR spectroscopy, in particular, 1H NMR, 1H-1H-NOESY, and 1H DOSY experiments complemented by quantum chemical calculations and cryo-TEM measurements. Through this mixture of methods, we identified curcumin-taurocholate interactions as central interaction patterns alongside interactions with the polymer and lipids. Furthermore, curcumin molecules can be exchanged between polymer micelles and bile colloids, an important prerequisite for their uptake. Finally, increased loading of the polymer micelles with curcumin resulted in a larger number of vesicles as taurocholate─through coordination with Cur─is less available to form nanoparticles with the lipids. The loading-dependent behavior found in this study deviates from previous work on a different drug substance highlighting the need for further studies including different drug molecules and polymer types to improve the understanding of events on the molecular level.

Complex Structures Made Simple - Continuous Flow Production of Core Cross-Linked Polymeric Micelles for Paclitaxel Pro-Drug-Delivery

Translating innovative nanomaterials to medical products requires efficient manufacturing techniques that enable large-scale high-throughput synthesis with high reproducibility. Drug carriers in medicine embrace a complex subset of tasks calling for multifunctionality. Here, the synthesisof pro-drug-loaded core cross-linked polymeric micelles (CCPMs) in a continuous flow processis reported, which combines the commonly separated steps of micelle formation, core cross-linking, functionalization, and purification into a single process. Redox-responsive CCPMs are formed from thiol-reactive polypept(o)ides of polysarcosine-block-poly(S-ethylsulfonyl-l-cysteine) and functional cross-linkers based on dihydrolipoic acid hydrazide for pH-dependent release of paclitaxel. The precisely controlled microfluidic process allows the production of spherical micelles (D_h  = 35 nm) with low polydispersity values (PDI < 0.1) while avoiding toxic organic solvents and additives with unfavorable safety profiles. Self-assembly and cross-linking via slit interdigital micromixers produces 350-700 mg of CCPMs/h per single system, while purification by online tangential flow filtration successfully removes impurities (unimer ≤ 0.5%). The formed paclitaxel-loaded CCPMs possess the desired pH-responsive release profile, display stable drug encapsulation, an improved toxicity profile compared to Abraxane (a trademark of Bristol-Myers Squibb), and therapeutic efficiency in the B16F1-xenotransplanted zebrafish model. The combination of reactive polymers, functional cross-linkers, and microfluidics enables the continuous-flow synthesis of therapeutically active CCPMs in a single process.

Injectable Poloxamer Hydrogel Formulations for Intratympanic Delivery of Dexamethasone

BACKGROUND

In this study, we prepared and evaluated an injectable poloxamer (P407) hydrogel formulation for intratympanic (IT) delivery of dexamethasone (DEX).

METHODS

DEX-loaded P407 hydrogels were characterized in terms of thermogelation, drug loading capacities, particle size, and drug release. The in vivo toxicity and drug absorption of the DEX-loaded P407 formulation after IT injection were evaluated using an animal model by performing histopathological analysis and drug concentration measurements.

RESULTS

The P407 hydrogel effectively solubilized hydrophobic DEX and demonstrated a sustained release compared to the hydrophilic DEX formulation. The in vivo study showed that the hydrogel formulation delivered considerable drug concentrations to the inner ear and displayed a favorable safety profile without apparent cytotoxicity or inflammation.

CONCLUSION

P407 hydrogel can be useful as an injectable inner ear delivery formulation for hydrophobic drugs due to their biocompatibility, drug-solubilizing capacity, thermogelation, and controlled release.

Cyclodextrin-Based Polymeric Drug Delivery Systems for Cancer Therapy

Cyclodextrins (CDs) are one of the most extensively studied cyclic-oligosaccharides due to their low toxicity, good biodegradability and biocompatibility, facile chemical modification, and unique inclusion capacity. However, problems such as poor pharmacokinetics, plasma membrane disruption, hemolytic effects and a lack of target specificity still exist for their applications as drug carriers. Recently, polymers have been introduced into CDs to combine the advantages of both biomaterials for the superior delivery of anticancer agents in cancer treatment. In this review, we summarize four types of CD-based polymeric carriers for the delivery of chemotherapeutics or gene agents for cancer therapy. These CD-based polymers were classified based on their structural properties. Most of the CD-based polymers were amphiphilic with the introduction of hydrophobic/hydrophilic segments and were able to form nanoassemblies. Anticancer drugs could be included in the cavity of CDs, encapsulated in the nanoparticles or conjugated on the CD-based polymers. In addition, the unique structures of CDs enable the functionalization of targeting agents and stimuli-responsive materials to realize the targeting and precise release of anticancer agents. In summary, CD-based polymers are attractive carriers for anticancer agents.

Evaluation of pH-Sensitive Polymeric Micelles Using Citraconic Amide Bonds for the Co-Delivery of Paclitaxel, Etoposide, and Rapamycin

Paclitaxel (PTX), etoposide (ETP), and rapamycin (RAPA) have different mechanisms, allowing multiple pathways to be targeted simultaneously, effectively treating various cancers. However, these drugs have a low hydrosolubility, limiting clinical applications. Therefore, we used pH-sensitive polymeric micelles to effectively control the drug release in cancer cells and to improve the water solubility of PTX, ETP, and RAPA. The synergistic effect of PTX, ETP, and RAPA was evaluated in gastric cancer, and the combination index values were evaluated. Thin-film hydration was used to prepare PTX/ETP/RAPA-loaded mPEG-pH-PCL micelles, and various physicochemical properties of these micelles were evaluated. In vitro cytotoxicity, pH-sensitivity, drug release profiles, in vivo pharmacokinetics, and biodistribution studies of PTX/ETP/RAPA-loaded mPEG-pH-PCL micelles were evaluated. In the pH-sensitivity evaluation, the size of the micelles increased more rapidly at a pH of 5.5 than at a pH of 7.4. The release rate of each drug increased with decreasing pH values in PTX/ETP/RAPA-loaded mPEG-pH-PCL micelles. In vitro and in vivo studies demonstrated that PTX/ETP/RAPA-loaded mPEG-pH-PCL micelles exhibit different drug release behaviors depending on the pH of the tumor and normal tissues and increased bioavailability and circulation time in the blood than solutions. Therefore, we propose that PTX/ETP/RAPA- loaded mPEG-pH-PCL micelles are advantageous for gastric cancer treatment in drug delivery systems.

Hydrotropic Hydrogels Prepared from Polyglycerol Dendrimers: Enhanced Solubilization and Release of Paclitaxel

Polyglycerol dendrimers (PGD) exhibit unique properties such as drug delivery, drug solubilization, bioimaging, and diagnostics. In this study, PGD hydrogels were prepared and evaluated as devices for controlled drug release with good solubilization properties. The PGD hydrogels were prepared by crosslinking using ethylene glycol diglycidylether (EGDGE). The concentrations of EGDGE and PGDs were varied. The hydrogels were swellable in ethanol for loading paclitaxel (PTX). The amount of PTX in the hydrogels increased with the swelling ratio, which is proportional to EGDGE/OH ratio, meaning that heterogeneous crosslinking of PGD made high dense region of PGD molecules in the matrix. The hydrogels remained transparent after loading PTX and standing in water for one day, indicating that PTX was dispersed in the hydrogels without any crystallization in water. The results of FTIR imaging of the PTX-loaded PGD hydrogels revealed good dispersion of PTX in the hydrogel matrix. Sixty percent of the loaded PTX was released in a sink condition within 90 min, suggesting that the solubilized PTX would be useful for controlled release without any precipitation. Polyglycerol dendrimer hydrogels are expected to be applicable for rapid release of poorly water-soluble drugs, e.g., for oral administration.

Synthesis and Evaluation of Thermoresponsive Renewable Lipid-Based Block Copolymers for Drug Delivery

Polymeric micelle forming from self-assembly of amphiphilic macromolecules is one of the most potent drug delivery systems. Fatty acids, naturally occurring hydrophobic lipid components, can be considered as potential candidates for the fabrication of block copolymer micelles. However, examples of synthesis of responsive block copolymers using renewable fatty acids are scarce. Herein, we report the synthesis, characterization and testing of block copolymer micelles composed of a renewable fatty-acid-based hydrophobic block and thermoresponsive hydrophilic block for controlled drug delivery. The block copolymers of functionalized fatty acid and poly(N-isopropylacrylamide) (PNIPAM) were prepared via consecutive microwave-assisted reversible addition fragmentation chain transfer (RAFT) polymerization. The block copolymers with variable hydrophobic block length self-assembled in aqueous media and formed spherical nanoparticles of ~30 nm with low critical micelle concentration (CMC). To demonstrate the proof-of-concept, carbamazepine (CBZ) was used as a hydrophobic model drug to evaluate the performance of these micelles as nanocarriers. The in vitro drug release tests were carried out below (25 °C) and above (37 °C) the lower critical solution temperature (LCST) of the block copolymer. The drug release showed obvious temperature-triggered response and an accelerated drug release at 37 °C.

Cell-Specific Metabolic Reprogramming of Tumors for Bioactivatable Ferroptosis Therapy

Ferroptosis is a nonapoptotic iron-dependent cell death pathway with a significant clinical potential, but its translation is impeded by lack of tumor-specific ferroptosis regulators and aberrant tumor iron metabolism. Herein, we report a combinational strategy based on clinically tested constituents to selectively induce ferroptosis in metabolically reprogrammed tumor cells through cooperative GPX4-inhibition and ferritinophagy-enabled Fe²⁺ reinforcement. Azido groups were first introduced on tumor cells using biocompatible long-circulating self-assemblies based on polyethylene glycol-disulfide-N-azidoacetyl-d-mannosamine via metabolic glycoengineering. The azido-expressing tumor cells could specifically react with dibenzocyclooctyne-modified disulfide-bridged nanoassemblies via bioorthogonal click reactions, where the nanoassemblies were loaded with ferroptosis inducer RSL3 and ferritinophagy initiator dihydroartemisinin (DHA) and could release them in a bioresponsive manner. DHA-initiated ferritinophagy could degrade intracellular ferritin to liberate stored iron species and cooperate with the RSL3-mediated GPX4-inhibition for enhanced ferroptosis therapy. This tumor-specific ferroptosis induction strategy provides a generally applicable therapy with enhanced translatability, especially for tumors lacking targetable endogenous receptors.

Progress in the field of hydrotropy: mechanism, applications and green concepts

Sustainability and greenness are the concepts of growing interest in the area of research as well as industries. One of the frequently encountered challenges faced in research and industrial fields is the solubility of the hydrophobic compound. Conventionally organic solvents are used in various applications; however, their contribution to environmental pollution, the huge energy requirement for separation and higher consumption lead to unsustainable practice. We require solvents that curtail the usage of hazardous material, increase the competency of mass and energy and embrace the concept of recyclability or renewability. Hydrotropy is one of the approaches for fulfilling these requirements. The phenomenon of solubilizing hydrophobic compound using hydrotrope is termed hydrotropy. Researchers of various fields are attracted to hydrotropy due to its unique physicochemical properties. In this review article, fundamentals about hydrotropes and various mechanisms involved in hydrotropy have been discussed. Hydrotropes are widely used in separation, heterogeneous chemical reactions, natural product extraction and pharmaceuticals. Applications of hydrotropes in these fields are discussed at length. We have examined the significant outcomes and correlated them with green engineering and green chemistry principles, which could give an overall picture of hydrotropy as a green and sustainable approach for the above applications.

Coarse-Grained Molecular Dynamics Simulations of Paclitaxel-Loaded Polymeric Micelles

A continuous manufacturing technology based on coaxial turbulent jet in coflow was previously developed to produce paclitaxel-loaded polymeric micelles. Herein, coarse-grained molecular dynamics (CG-MD) simulations were implemented to better understand the effect of the material attributes (i.e., the drug-polymer ratio and the ethanol concentration) and process parameters (i.e., temperature) on the self-assembly process of polymeric micelles as well as to provide molecular details on micelle instability. An all-atom (AA) poly (ethylene glycol)-poly (lactic acid) (PEG-PLA) polymer model was developed as the reference for parameterizing a coarse-grained (CG) model, and the AA polymer model was further validated with experimental glass transition temperature (T_g). The model transferability was verified by comparing structural properties between the AA and CG models. The CG model was further validated with experimental data, including micelle particle size measurements and drug encapsulation efficiency. Furthermore, the encapsulation of paclitaxel into the polymeric micelles was included in the simulations, taking into consideration the interactions between the paclitaxel and the polymers. The results from various points of view demonstrated a strong dependence of the shape of the micelles on the drug encapsulation, with micelles transitioning from spherical to ellipsoidal structures with an increasing paclitaxel amount. Simulation data were also used to identify the critical aggregation number (i.e., the number of polymer and drug molecules required for transition from one shape to another). Improved micellar structural stability was found with a larger micellar size and less solvent accessibility. Lastly, an evaluation was performed on the micellar dissociation free energy using a steered molecular dynamics simulation over a range of temperatures and ethanol concentrations. These simulations revealed that at higher ethanol and temperature conditions, micelles become destabilized, resulting in greater paclitaxel release. The increased drug release was determined to originate from the solvation of the hydrophobic core, which promoted micellar swelling and an associated reduction in hydrophobic interactions, leading to a loosely packed micellar structure.

Towards principled design of cancer nanomedicine to accelerate clinical translation

Nanotechnology in medical applications, especially in oncology as drug delivery systems, has recently shown promising results. However, although these advances have been promising in the pre-clinical stages, the clinical translation of this technology is challenging. To create drug delivery systems with increased treatment efficacy for clinical translation, the physicochemical characteristics of nanoparticles such as size, shape, elasticity (flexibility/rigidity), surface chemistry, and surface charge can be specified to optimize efficiency for a given application. Consequently, interdisciplinary researchers have focused on producing biocompatible materials, production technologies, or new formulations for efficient loading, and high stability. The effects of design parameters can be studied in vitro, in vivo, or using computational models, with the goal of understanding how they affect nanoparticle biophysics and their interactions with cells. The present review summarizes the advances and technologies in the production and design of cancer nanomedicines to achieve clinical translation and commercialization. We also highlight existing challenges and opportunities in the field.

Engineered strategies to enhance tumor penetration of drug-loaded nanoparticles

Nanocarriers have been widely employed in preclinical studies and clinical trials for the delivery of anticancer drugs. The most important causes of failure in clinical translation of nanocarriers is their inefficient accumulation and penetration which arises from special characteristics of tumor microenvironment such as insufficient blood supply, dense extracellular matrix, and elevated interstitial fluid pressure. Various strategies such as engineering extracellular matrix, optimizing the physicochemical properties of nanocarriers have been proposed to increase the depth of tumor penetration; however, these strategies have not been very successful so far. Novel strategies such as transformable nanocarriers, transcellular transport of peptide-modified nanocarriers, and bio-inspired carriers have recently been emerged as an advanced generation of drug carriers. In this study, the latest developments of nanocarrier-based drug delivery to solid tumor are presented with their possible limitations. Then, the prospects of advanced drug delivery systems are discussed in detail.

Soft materials as biological and artificial membranes

The past few decades have seen emerging growth in the field of soft materials for synthetic biology. This review focuses on soft materials involved in biological and artificial membranes. The biological membranes discussed here are mainly those involved in the structure and function of cells and organelles. As building blocks in medicine, non-native membranes including nanocarriers (NCs), especially liposomes and DQAsomes, and polymeric membranes for scaffolds are constructed from amphiphilic combinations of lipids, proteins, and carbohydrates. Artificial membranes can be prepared using synthetic, soft materials and molecules and then incorporated into structures through self-organization to form micelles or niosomes. The modification of artificial membranes can be realized using traditional chemical methods such as click reactions to target the delivery of NCs and control the release of therapeutics. The biomembrane, a lamellar structure inlaid with ion channels, receptors, lipid rafts, enzymes, and other functional units, separates cells and organelles from the environment. An active domain inserted into the membrane and organelles for energy conversion and cellular communication can target disease by changing the membrane's composition, structure, and fluidity and affecting the on/off status of the membrane gates. The biological membrane targets analyzing pathological mechanisms and curing complex diseases, which inspires us to create NCs with artificial membranes.

Enhanced antitumor efficacy of glutathione-responsive chitosan based nanoparticles through co-delivery of chemotherapeutics, genes, and immune agents

To achieve the co-delivery of chemotherapeutic drugs, genes, and immune agents in a single nanoparticulate system, p-mercaptobenzoic acid-grafted N, N, N-trimethyl chitosan nanoparticles (MT NPs) were successfully synthesized. Paclitaxel (PTX) was encapsulated into the hydrophobic core of the MT NPs, and meanwhile, survivin shRNA-expressing plasmid (iSur-pDNA) and recombinant human interleukin-2 (rhIL-2) were loaded onto the hydrophilic shell of the MT NPs. Owing to the redox-sensitiveness of MT NPs, a rapid release of PTX was triggered by the high concentration of glutathione. The synergistic effects of PTX (1.5 mg/kg), iSur-pDNA (1.875 mg/kg), and rhIL-2 (6 × 10⁵ IU/kg) at a low dose endowed the MT/PTX/pDNA/rhIL-2 NPs with enhanced antitumor efficacies and improved tumor-induced immunosuppression. These results demonstrated that the co-delivery of PTX, iSur-pDNA, and rhIL-2 by the amphiphilic chitosan based NPs with redox-sensitiveness could be a promising strategy in the treatment of tumors.

Continuous processing of paclitaxel polymeric micelles

A continuous polymeric micelle processing platform was successfully developed, which eliminated batch-to-batch variation in critical quality attributes (for example, size and polydispersity that are typically associated with batch processing). A continuous precipitation process was achieved via coaxial turbulent jet in co-flow technology allowing precise control of particle size with average particle size in the range 15 to 70 nm and low polydispersity. Critical relationships between material attributes (e.g., block copolymer design), process parameters (e.g., polymer concentration, organic to aqueous flow rate ratios, and temperature), and critical quality attributes (e.g., size and polydispersity) of the polymeric micelles were realized via multiple designs of experiments studies. Both polymer molecular weight and concentration were shown to influence the micelle polydispersity index. Notably, higher molecular weight polymer required higher processing temperatures to produce monodispersed particles and were generally of larger size. Using optimized conditions, paclitaxel polymeric micelles that are qualitatively and quantitatively equivalent to commercial Genexol PM were produced, exhibiting comparable quality attributes including particle size, size distribution, morphology, drug loading, release characteristics, and stability. Lastly, a dynamic light scattering method was adapted to determine the critical micelle concentration and aggregation number of the block copolymers, providing useful information about the raw material.

In Vitro and In Vivo Studies on HPMA-Based Polymeric Micelles Loaded with Curcumin

Curcumin-loaded polymeric micelles composed of poly(ethylene glycol)-b-poly(N-2-benzoyloxypropyl methacrylamide) (mPEG-b-p(HPMA-Bz)) were prepared to solubilize and improve the pharmacokinetics of curcumin. Curcumin-loaded micelles were prepared by a nanoprecipitation method using mPEG_5kDa-b-p(HPMA-Bz) copolymers with varying molecular weight of the hydrophobic block (5.2, 10.0, and 17.1 kDa). At equal curcumin loading, micelles composed of mPEG_5kDa-b-p(HPMA-Bz)_17.1kDa showed better curcumin retention in both phosphate-buffered saline (PBS) and plasma at 37 °C than micelles based on block copolymers with smaller hydrophobic blocks. No change in micelle size was observed during 24 h incubation in plasma using asymmetrical flow field-flow fractionation (AF₄), attesting to particle stability. However, 22-49% of the curcumin loading was released from the micelles during 24 h from formulations with the highest to the lowest molecular weight p(HPMA-Bz), respectively, in plasma. AF₄ analysis further showed that the released curcumin was subsequently solubilized by albumin. In vitro analyses revealed that the curcumin-loaded mPEG_5kDa-b-p(HPMA-Bz)_17.1kDa micelles were internalized by different types of cancer cells, resulting in curcumin-induced cell death. Intravenously administered curcumin-loaded, Cy7-labeled mPEG_5kDa-b-p(HPMA-Bz)_17.1kDa micelles in mice at 50 mg curcumin/kg showed a long circulation half-life for the micelles (t_1/2 = 42 h), in line with the AF₄ results. In contrast, the circulation time of curcumin was considerably shorter than that of the micelles (t_1/2α = 0.11, t_1/2β = 2.5 h) but ∼5 times longer than has been reported for free curcumin (t_1/2α = 0.02 h). The faster clearance of curcumin in vivo compared to in vitro studies can be attributed to the interaction of curcumin with blood cells. Despite the excellent solubilizing effect of these micelles, no cytostatic effect was achieved in neuroblastoma-bearing mice, possibly because of the low sensitivity of the Neuro2A cells to curcumin.

Synthesis, characterisation and functionalisation of BAB-type dual-responsive nanocarriers for targeted drug delivery: evolution of nanoparticles based on 2-vinylpyridine and diethyl vinylphosphonate

The emerging field of nanomedicine gives new opportunities in the treatment of cancer. Aspects such as dosage, bioavailability or the application to the patient can be drastically improved. Previously our group reported an efficient route towards cross-linked nanospheres based on ABB' block copolymers made from 2-vinylpyridine (2VP), diethyl vinylphosphonate (DEVP) and diallyl vinylphosphonate (DAlVP). Followed by thiol-ene click chemistry stable nanoparticles were formed. Herein, this promising concept was extended to copolymers with the analogous B'BABB' architecture. In this context the new yttrium complex 5 was investigated in the rare-earth metal-mediated group transfer polymerisation (REM-GTP) and used for the generation of copolymers with different monomer feeds (2VP: 100-300 equiv.; DEVP: 200-300 equiv.; DAlVP: 6-20 equiv.) to explore the influence of the copolymer compositon on the nanoparticle properties. After successful cross-linking with various cross-linking agents, all nanoparticles were characterised via DLS and TEM. These size measurements revealed defined, almost spherical particles (d DLS = 17-52 nm; d TEM = 17-43 nm) and were mainly affected by the 2VP content and the cross-linking density. Zeta potential measurements resulted in values in the range from -6 mV to -22 mV and revealed an influence of the cross-linking agent on the surface charge. Studies on the release behaviour exhibited the fastest release at pH = 4.5. Temperature-wise best results were achieved at 42 °C. Furthermore, we aimed for the conjugation of folic acid as a model compound for a potential application in active drug targeting. The consecutive couplings of cysteamine and dithiol 6 enabled the formation of an amine-modified precursor which was reacted with a folic acid derivative. Zeta potential measurements and analysis by NMR spectroscopy corroborated a successful conjugation while DLS and TEM (d DLS = 44 nm; d TEM = 38 nm) indicated defined nanoparticles.

Nanocapsules containing Saussurea lappa essential oil: Formulation, characterization, antidiabetic, anti-cholinesterase and anti-inflammatory potentials

Plant-based remedies have been widely used for the management of variable diseases due to their safety and less side effects. In the present study, we investigated Saussurea lappa CB. Clarke. (SL) given its largely reported medicinal effects. Specifically, our objective was to provide an insight into a new polymethyl methacrylate based nanocapsules as carriers of SL essential oil and characterize their biologic functions. The nanoparticles were prepared by nanoprecipitation technique, characterized and analyzed for their cytotoxicity, anti-inflammatory, anti-Alzheimer and antidiabetic effects. The results revealed that the developed nanoparticles had a diameter around 145 nm, a polydispersity index of 0.18 and a zeta potential equal to +45 mV and they did not show any cytotoxicity at 25 μg·mL^-1. The results also showed an anti-inflammatory activity (reduction in metalloprotease MMP-9 enzyme activity and RNA expression of inflammatory cytokines: TNF-α, GM-CSF and IL1β), a high anti-Alzheimer's effect (IC50 around 25.0 and 14.9 μg·mL^-1 against acetylcholinesterase and butyrylcholinesterase, respectively), and a strong antidiabetic effect (IC50 were equal to 22.9 and 75.8 μg·mL^-1 against α-amylase and α-glucosidase, respectively). Further studies are required including the in vivo studies (e.g., preclinical), the pharmacokinetic properties, the bioavailability and the underlying associated metabolic pathways.

Polymeric micelles for anticancer drug delivery

Polymeric micelles have gained interest as novel drug delivery systems for the treatment and diagnosis of cancer, as they offer several advantages over conventional drug therapies. This includes drug targeting to tumor tissue, in vivo biocompatibility and biodegradability, prolonged circulation time, enhanced accumulation, retention of the drug loaded micelle in the tumor and decreased side effects. This article provides an overview on the current state of micellar formulations as nanocarriers for anticancer drugs and their effectiveness in cancer therapeutics, including their clinical status. The type of copolymers used, their physicochemical properties and characterization as well as recent developments in the design of functional polymeric micelles are highlighted. The article also presents the design and outcomes of various types of stimuli-responsive polymeric micelles.

Polymeric micelles for anticancer drug delivery

Polymeric micelles have gained interest as novel drug delivery systems for the treatment and diagnosis of cancer, as they offer several advantages over conventional drug therapies. This includes drug targeting to tumor tissue, in vivo biocompatibility and biodegradability, prolonged circulation time, enhanced accumulation, retention of the drug loaded micelle in the tumor and decreased side effects. This article provides an overview on the current state of micellar formulations as nanocarriers for anticancer drugs and their effectiveness in cancer therapeutics, including their clinical status. The type of copolymers used, their physicochemical properties and characterization as well as recent developments in the design of functional polymeric micelles are highlighted. The article also presents the design and outcomes of various types of stimuli-responsive polymeric micelles.

pH-Responsive Lignin-Based Nanomicelles for Oral Drug Delivery

A pH-stimuli amphiphilic lignin-based copolymer was prepared, and it could self-assemble to form spherical nanomicelles with the addition of "switching" water. The morphology, structure, and physical properties of micelles were characterized with transmission electron microscopy (TEM), nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), particle-size analysis, and zeta-potential measurement. In vitro drug release exemplified that the micelles were pH-sensitive, retaining more than 84.36% ibuprofen (IBU) in simulated gastric fluid (pH 1.5) and presenting a smooth release of 81.81% IBU in simulated intestinal fluid (pH 7.4) within 72 h. Cell culture studies showed that the nanomicelles were biocompatible and boosted the proliferation of human bone marrow stromal cells hBMSC and mouse embryonic fibroblast cells NIH-3T3. Interestingly, the nanomicelles inhibited the survival of human colon cancer cells HT-29 with a final survival rate of only 5.34%. Therefore, this work suggests a novel strategy to synthesize intelligent lignin-based nanomicelles that show a great potential as oral drug carriers.

New intranasal cross-linked mosapride xyloglucan pluronics micelles (MOS-XPMs) for reflux esophagitis disease: In-vitro optimization and improved therapeutic efficacy

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Mosapride was loaded inside crosslinked Xyloglucan Pluronic micelle (MOS-XPMs).

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(MOS-XPMs) showed improved stability and mucoadhesiveness.

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MOS-XPMs systems showed a rapid release of drug located in the shell within 0.5hr followed by a consistent release pattern for the remaining 8hr.

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Trans-abdominal ultrasonography XPMs showed 1.5 fold increased in duodenal and cecal motility compared to MOS suspension.

Mosapride belongs to class IV in Biopharmaceutics Classification System and is used in the treatment of reflux esophagitis. It exhibits poor bioavailability due to limited permeability, solubility and extensive first-pass metabolism. In this study, intranasal mosapride-loaded cross-linked xyloglucan Pluronic micelles (MOS-XPMs) was formulated and optimized to improve the low solubility & bioavailability of MOS. The solid dispersion technique using 2³ full factorial design was applied. (MOS-XPMs) (F4) had the highest desirability value (0.952) and, therefore, it was selected as an optimal system. Xyloglucan cross-linked in the shell of Pluronic micelles offered improved stability and mucoadhesiveness to MOS-XPMs. ¹H NMR spectra ensured the cross-linking of xyloglucan with Pluronic micelle shell and micelle stabilization. A Pharmacodynamic study revealed that MOS-XPMs showed 1.5-fold increase in duodenal and cecal motility compared to MOS suspension and 1.7-fold increase compared to the oral marketed product. The new MOS-XPMs were shown to be successful at improving the therapeutic efficacy of mosapride.

Polymeric micelles loading with ursolic acid enhancing anti-tumor effect on hepatocellular carcinoma

Ursolic acid (UA) is widely found in many dietary plants, which has been proved to be effective in cancer therapy. But unfortunately its hydrophobic property limits its clinical application. Polymer micelles (PMs) are constructed from amphiphilic block copolymers that tend to self-assemble and form the unique core-shell structure consisting of a hydrophilic corona outside and a hydrophobic inner core. PMs could entrap the hydrophobic substance into its hydrophobic inner core for solubilizing these poorly water-soluble drugs and it is widely applied as a novel nano-sized drug delivery system. This study aimed to develop the drug delivery system of UA-loaded polymer micelles (UA-PMs) to overcome the disadvantages of UA in clinical application thus enhancing antitumor effect on hepatocellular carcinoma. UA-PMs was prepared and characterized for the physicochemical properties. It was investigated the cell-growth inhibition effect of UA-PMs against the human hepatocellular carcinoma cell line HepG2 and human normal liver cell line L-02. UA-PMs was evaluated about the in vivo toxicity and the antitumor activity. We took a diblock copolymer of methoxy poly (ethylene glycol)-poly(L-lactic acid) (mPEG-PLA) as carrier material to prepare UA-PMs by the thin-film dispersion method. MTT assay and wound-healing assay were investigated to assess the inhibition effect of UA-PMs against HepG2 cells on cell-growth and cell-migration. Further, we chose KM mice for the acute toxicity experiment and assessed the antitumor effect of UA-PMs on the H22 tumor xenograft. UA-PMs could markedly inhibit the proliferation and migration of HepG2 cells. In vivo study showed that UA-PMs could significantly inhibit the growth of H22 xenograft and prolong the survival time of tumor-bearing mice. It demonstrated that UA-PMs possess great potential in liver cancer therapy and may enlarge the application of UA in clinical therapy.

PEG-Derivatized Dual-Functional Nanomicelles for Improved Cancer Therapy

Polymeric micelles have attracted considerable attention for effective delivery of poorly water-soluble cancer drugs. Polyethylene glycol (PEG), which has been approved for human use by the US Food and Drug Administration, is the most commonly used hydrophilic component of polymeric micelles because it is biocompatible and biodegradable. One disadvantage of traditional polymeric micelles is that they include a large amount of inert carrier materials, which do not contribute to therapeutic activity but increase cost and toxicity risk. A better alternative may be "dual-functional" micellar carriers, in which the hydrophobic carrier material (conjugated to PEG) has intrinsic therapeutic activity that complements, or even synergizes with, the antitumor activity of the drug cargo. This review summarizes recent progress in the development of PEG-derivatized dual-functional nanomicelles and surveys the evidence of their feasibility and promise for cancer therapy.

A nano-sized blending system comprising identical triblock copolymers with different hydrophobicity for fabrication of an anticancer drug nanovehicle with high stability and solubilizing capacity

Background: A very common and simple method (known as the blending method) to formulate drug delivery systems with required properties is to physically mix amphiphilic block copolymers with different hydrophobicity. In addition to its simplicity, this blending strategy could help avoid the time and effort involved in the synthesis of block copolymers with the desired structure required for specific drug formulations. Purpose: We used the blending strategy to design a system that could overcome the problem of high hydrophobicity and be a good candidate for drug product development using PEG-PLA-PEG triblock copolymers. Methods: Two types of PEG-PLA-PEG triblock copolymers with similar (long) PLA molecular weights (MWs) and different PEG MWs were synthesized. The micellar formulations were prepared by blending the two block copolymers in various ratios. The size and stability of the blending systems were subsequently investigated to optimize the formulations for further studies. The loading properties of doxorubicin or paclitaxel into the optimized blending system were compared to that in mono systems (systems composed of only a single type of triblock copolymer). In vitro and in vivo anti-cancer effects of the preparations were evaluated to assess the use of the blending system as an optimal nanomedicine platform for insoluble anticancer agents. Results: The blending system (B20 system) with an optimized ratio of the triblock copolymers overcame the drawbacks of mono systems. Drug uptake from the drug-loaded B20 system and its anticancer effects against KB cells were superior compared to those of free drugs (doxorubicin hydrochloride and free paclitaxel). In particular, doxorubicin-loaded B20 resulted in extensive doxorubicin accumulation in tumor tissues and significantly higher in vivo anti-cancer effects compared to free doxorubicin. Conclusion: The blending system reported here could be a potential nanoplatform for drug delivery due to its simplicity and efficiency for pharmaceutical application.

Design and synthesis of mixed micellar system for enhanced anticancer efficacy of Paclitaxel through its co-delivery with Naringin

Emergence of multidrug resistance (MDR) has limited the success of chemotherapeutic agents. Reversal of drugs efflux systems through combination therapy has got wider attention for increasing anticancer drugs efficacy. This study aims at co-encapsulation of Paclitaxel with Naringin in mixed polymeric micelles for enhanced anticancer activity of the drug. Drug-loaded micelles were prepared using two different amphiphilic block co-polymers and were characterized for morphology, size, zeta potential, drug encapsulation, in vitro release and stability using atomic force microscope (AFM), zetasizer, UV spectrophotometer, and FT-IR. MTT assay and fluorescence microscopy were used for in vitro cytotoxicity and cellular uptake studies. Nano-size micelles with spherical morphology and negative charge encapsulated 76.52 ± 0.94% and 32.87 0.61% Paclitaxel and Naringin, respectively. The micelles were thermally stable and retained 87.05 ± 0.69% and 92.88 ± 2.17% Paclitaxel and Naringin upon one-month storage. Maximum drug release was achieved at fourth hour of the study for both the loaded drugs. Paclitaxel co-encapsulation with Naringin synergistically improved its intracellular uptake and 65% in vitro cytotoxicity against breast cancer cells was achieved at its lower dose of 15 µg/mL. Results suggest that co-encapsulation of Paclitaxel with Naringin in mixed micelles is an effective strategy for achieving its higher anticancer activity.

Poly(ethylene glycol)-block-poly(d,l-lactic acid) micelles containing oligo(lactic acid)8-paclitaxel prodrug: In Vivo conversion and antitumor efficacy

Poly(ethylene glycol)-block-poly(d,l-lactic acid) (PEG-b-PLA) micelles affect drug solubilization, and a paclitaxel (PTX) loaded-PEG-b-PLA micelle (PTX-PM) is approved for cancer treatment due to injection safety and dose escalation (Genexol-PM®) compared to Taxol®. However, PTX-PM is unstable in blood, has rapid clearance, and causes dose-limiting toxicity. We have synthesized a prodrug for PTX (7-OH), using oligo(lactic acid) as a novel pro-moiety (o(LA)₈-PTX) specifically for PEG-b-PLA micelles, gaining higher loading and slower release of o(LA)₈-PTX over PTX. Notably, o(LA)₈-PTX prodrug converts into PTX by a backbiting reaction in vitro, without requiring esterases. We hypothesize that o(LA)₈-PTX-loaded PEG-b-PLA micelles (o(LA)₈-PTX-PM) has a lower C_max and higher plasma AUC than PTX-PM for improved therapeutic effectiveness. In Sprague-Dawley rats at 10 mg/kg, compared to o(LA)₈-PTX-PM (10% w/w loading) and PTX-PM (10%), o(LA)₈-PTX-PM (50% w/w loading) produces a 2- and 3-fold higher plasma AUC_0-24 of PTX, lactic acid-PTX, and o(LA)₂-PTX (o(LA)_0-2-PTX), respectively. For o(LA)₈-PTX-PM at 10 and 50% w/w loading, PTX and lactic acid-PTX are major bioactive metabolites, respectively. Fast prodrug conversion of o(LA)₈-PTX in vivo versus in vitro (by backbiting) suggests that o(LA)₈ is a good substrate for esterases. At 60 mg/kg (qwx3), o(LA)₈-PTX-PM (50%) has higher antitumor activity than o(LA)₈-PTX-PM (10%) and PTX-PM (10%) in a syngeneic 4T1-luc breast tumor model based on measurements of tumor volume, 4T1-luc breast tumor bioluminescence, and survival. Importantly, intravenous administration of o(LA)₈-PTX-PM is well tolerated by BALB/c mice. In summary, oligo(lactic acid)₈-PTX is more compatible than PTX with PEG-b-PLA micelles, more stable, and may expand the role of PEG-b-PLA micelles from "solubilizer" into "nanocarrier" for PTX as a next-generation taxane for cancer.

Improving antitumor outcomes for palliative intratumoral injection therapy through lecithin- chitosan nanoparticles loading paclitaxel- cholesterol complex

Background

Intratumoral injection is a palliative treatment that aims at further improvement in the survival and quality of life of patients with advanced or recurrent carcinomas, or cancer patients with severe comorbidities or those with a poor performance status.

Methods

In this study, a solvent-injection method was used to prepare paclitaxel–cholesterol complex-loaded lecithin–chitosan nanoparticles (PTX-CH-loaded LCS_NPs) for intratumoral injection therapy, and the physicochemical properties of NPs were well characterized.

Results

The particle size and zeta potential of PTX-CH-loaded LCS_NPs were 142.83±0.25 nm and 13.50±0.20 mV, respectively. Release behavior of PTX from PTX-CH-loaded LCS_NPs showed a pH-sensitive pattern. The result of cell uptake assay showed that PTX-CH-loaded LCS_NPs could effectively enter cells via the energy-dependent caveolae-mediated endocytosis and macropinocytosis in company with the Golgi apparatus. Meanwhile, PTX-CH-loaded LCS_NPs had a better ability to induce cell apoptosis than PTX solution. The in vivo antitumor results suggested that PTX-CH-loaded LCS_NPs effectively inhibited mouse mammary cancer growth and metastasis to distant organs and significantly improved the survival rate of tumor-bearing mice by intratumoral administration.

Conclusion

In general, our study demonstrated that PTX-CH-loaded LCS_NPs used for palliative treatment by intratumoral injection showed improved safety and antitumor efficacy, which provided an alternative approach in the field of palliative chemotherapy.

In vitro and in vivo evaluation of a novel mitomycin nanomicelle delivery system

Mitomycin C (MMC), naturally synthesized by Streptomyces caespitosus, is a potent antineoplastic antibiotic for the treatment of various solid tumors. However, the defects of conventional MMC injections have greatly limited its clinical application due to its toxic side effects and non-specific interactions. To solve this problem, the PEG_2k-Fmoc-Ibuprofen (PEG-FIbu) micellar nanocarrier was synthesized and the MMC-loaded micelles (PEG-FIbu/MMC) were prepared by thin film hydration method and characterized. Ibuprofen was used as a hydrophobic domain of PEG-FIbu nanocarrier, and we expect it to synergize with codelivered MMC in the overall antitumor activity. The in vitro release of PEG-FIbu/MMC was examined by dialysis method using MMC injection as a control. Our data suggested that PEG-FIbu/MMC micelles presented appropriate particle size, low CMC value, good stability, high drug loading efficiency and sustained release properties. In vitro cytotoxicity studies with several tumor cell lines showed that the carrier was effective in mediating intracellular delivery of MMC to tumor cells. In vivo pharmacokinetics, tissue distribution and therapeutic study proved that PEG-FIbu/MMC micelles prolonged blood circulation, significantly improved the tumor accumulation and therapeutic efficacy, and reduced undesirable side effect on normal tissues compared to MMC injection. In general, PEG-FIbu/MMC micelles represented an effective strategy to improve the performance for the delivery of MMC and safety of medication.

The introduction of a micellar delivery system of MMC increase efficiency, reduce toxicity and enhance specific interactions in tumor.

A personalized and long-acting local therapeutic platform combining photothermal therapy and chemotherapy for the treatment of multidrug-resistant colon tumor

BACKGROUND

Local photothermal therapy (PTT) provides an easily applicable, noninvasive adjunctive therapy for colorectal cancer (CRC), especially when multidrug resistance (MDR) occurs. However, using PTT alone does not result in complete tumor ablation in many cases, thus resulting in tumor recurrence and metastasis.

MATERIALS AND METHODS

In this study, we aim to develop a personalized local therapeutic platform combining PTT with long-acting chemotherapy for the treatment of MDR CRC. The platform consists of polyethylene glycol (PEG)-coated gold nanorods (PEG-GNRs) and D-alpha-tocopheryl PEG 1000 succinate (TPGS)-coated paclitaxel (PTX) nanocrystals (TPGS-PTX NC), followed by the incorporation into an in situ hydrogel (gel) system (GNRs-TPGS-PTX NC-gel) before injection. After administration, PEG-GNRs can exert quick and efficient local photothermal response under near-infrared laser irradiation to shrink tumor; TPGS-PTX NC then provides a long-acting chemotherapy due to the sustained release of PTX along with the P-glycoprotein inhibitor TPGS to reverse the drug resistance.

RESULTS

The cytotoxicity studies showed that the IC50 of GNRs-TPGS-PTX NC-gel with laser irradiation decreased to ~178-folds compared with PTX alone in drug-resistant SW620 AD300 cells. In the in vivo efficacy test, after laser irradiation, the GNRs-TPGS-PTX NC-gel showed similar tumor volume inhibition compared with GNRs-gel at the beginning. However, after 14 days, the tumor volume of the mice treated with GNRs-gel quickly increased, while that of the mice treated with GNRs-TPGS-PTX NC-gel remained controllable due to the long-term chemotherapeutic effect of TPGS-PTX NC. The mice treated with GNRs-TPGS-PTX NC-gel also showed no weight loss and obvious organ damages and lesions during the treatment, indicating a low systemic side effect profile and a good biocompatibility.

CONCLUSION

Overall, the nano-complex may serve as a promising local therapeutic patch against MDR CRC with one-time dosing to achieve a long-term tumor control. The doses of PEG-GNRs and TPGS-PTX NC can be easily adjusted before use according to patient-specific characteristics potentially making it a personalized therapeutic platform.

Interactions of polymeric drug carriers with DDT reduce their combined cytotoxicity

Attention has been paid to the environmental distribution and fate of nanomedicines. However, their effects on the toxicity of environmental pollutants are lack of knowledge. In this study, the negatively charged poly (ethylene glycol)-b-poly (L-lactide-co-glycolide) (mPEG-PLA) and positively charged polyethyleneimine-palmitate (PEI-PA) nanomicelles were synthesized and served as model drug carriers to study the interaction and combined toxicity with dichlorodiphenyltrichloroethane (DDT). DDT exerted limited effect on the biointerfacial behavior of mPEG-PLA nanomicelles, whereas it significantly mitigated the attachment of PEI-PA nanomicelles on the model cell membrane as monitored by quartz crystal microbalance with dissipation (QCM-D). The cytotoxicity of DDT towards NIH 3T3 cells was greatly decreased by either co-treatment or pre-treatment with the nanomicelles according to the results of real-time cell analysis (RTCA). The cell viability of NIH 3T3 exposed to DDT was increased up to 90% by the co-treatment with mPEG-PLA nanomicelles. Three possible reasons were proposed: (1) decreased amount of free DDT in the cell culture medium due to the partitioning of DDT into nanomicelles; (2) mitigated cellular uptake of nanomicelle-DDT complexes due to the complex agglomeration or electrostatic repulsion between complexes and cell membrane; (3) detoxification effect in the lysosome upon endocytosis of nanomicelle-DDT complexes.

Facile Strategy Enabling Both High Loading and High Release Amounts of the Water-Insoluble Drug Clofazimine Using Mesoporous Silica Nanoparticles

The use of nanocarriers to deliver poorly soluble drugs to the sites of diseases is an attractive and general method, and mesoporous silica nanoparticles (MSNs) are increasingly being used as carriers. However, both loading a large amount of drugs into the pores and still being able to release the drug is a challenge. In this paper, we demonstrate a general strategy based on a companion molecule that chaperones the drug into the pores and also aids it in escaping. A common related strategy is to use a miscible co-solvent dimethyl sulfoxide (DMSO), but although loading may be efficient in DMSO, this co-solvent frequently diffuses into an aqueous environment, leaving the drug behind. We demonstrate the method by using acetophenone (AP), an FDA-approved food additive as the chaperone for clofazimine (CFZ), a water-insoluble antibiotic used to treat leprosy and multidrug-resistant tuberculosis. AP enables a high amount of CFZ cargo into the MSNs and also carries CFZ cargo out from the MSNs effectively when they are in an aqueous biorelevant environment. The amount of loading and the CFZ release efficiency from MSNs were optimized; 4.5 times more CFZ was loaded in MSNs with AP than that with DMSO and 2300 times more CFZ was released than that without the assistance of the AP. In vitro treatment of macrophages infected by Mycobacterium tuberculosis with the optimized CFZ-loaded MSNs killed the bacteria in the cells in a dose-dependent manner. These studies demonstrate a highly efficient method for loading nanoparticles with water-insoluble drug molecules and the efficacy of the nanoparticles in delivering drugs into eukaryotic cells in aqueous media.

Engineering docetaxel-loaded micelles for non-small cell lung cancer: a comparative study of microfluidic and bulk nanoparticle preparation

Bulk preparation of micelles has the drawbacks of facile formation of large aggregates and heterogeneous particle size distribution. Microfluidic technology has shown clear potential to address these challenges for robust nanomedicine applications. In this study, docetaxel-loaded PLGA-PEG-Mal-based micelles were prepared by microfluidics and dialysis methods and their physicochemical properties were analyzed. The biological behaviors of these micelles were also investigated in the non-small cell lung cancer (NSCLC) cell line A549 in vitro as well as in vivo. Encouragingly, the mean particle size of the micelles prepared by microfluidics (DMM) was smaller, with an average size of 72 ± 1 nm and a narrow size distribution with a polydispersity index (PDI) of 0.072; meanwhile, micelles prepared by the dialysis method (DMD) had larger particle sizes (range, 102 to 144 nm) and PDIs (up to 0.390). More importantly, significantly high drug loading was achieved using the microfluidic process. The IC50 value of DMM was lower than that of DMD. Whole-body fluorescence imaging of live mice showed that DMM achieved higher accumulation in tumors compared with DMD. DMM showed superior antitumor efficacy, with a tumor inhibition rate of 91.5%. Moreover, pathological histology analysis revealed that no evident biological toxicity was caused by the micelles. In addition, Arg-Gly-Asp (RGD) was employed as a targeting agent on the basis of DMM to prepare targeting micelles, and the targeting micelles exhibited stronger cytotoxicity and obvious antitumor efficacy. In conclusion, DMM may have obvious clinical advantages for the treatment of NSCLC due to its optimized physiochemical properties. Therefore, microfluidic technology-based micelles are a promising platform as an effective drug delivery system for incorporating anticancer agents.

Polymeric Micelles of Biodegradable Diblock Copolymers: Enhanced Encapsulation of Hydrophobic Drugs

Polymeric micelles are potentially efficient in encapsulating and performing the controlled release of various hydrophobic drug molecules. Understanding the fundamental physicochemical properties behind drug⁻polymer systems in terms of interaction strength and compatibility, drug partition coefficient (preferential solubilization), micelle size, morphology, etc., encourages the formulation of polymeric nanocarriers with enhanced drug encapsulating capacity, prolonged circulation time, and stability in the human body. In this review, we systematically address some open issues which are considered to be obstacles inhibiting the commercial availability of polymer-based therapeutics, such as the enhancement of encapsulation capacity by finding better drug⁻polymer compatibility, the drug-release kinetics and mechanisms under chemical and mechanical conditions simulating to physiological conditions, and the role of preparation methods and solvents on the overall performance of micelles.

Self-assembled filomicelles prepared from polylactide-poly(ethylene glycol) diblock copolymers for sustained delivery of cycloprotoberberine derivatives

Polylactide-poly(ethylene glycol) (PLA-PEG) block copolymers were synthesized by ring opening polymerization of l-lactide using a monomethoxy PEG (mPEG) as macroinitiator and zinc lactate as catalyst. The resulting diblock copolymers were characterized by ¹H NMR and GPC. Polymeric micelles were prepared by self-assembly of copolymers in distilled water using co-solvent evaporation or membrane hydration methods. The resulting micelles are worm-like in shape as shown by TEM measurements. A hydrophobic anticancer drug, cycloprotoberberine derivative A35, was successfully loaded in PLA-PEG filomicelles with high encapsulation efficiency (above 88%). Berberine (BBR) was studied for comparison. In both methods, PLA-PEG filomicelles were prepared with a theoretical loading of 5%, 10% and 20%. Physical stability studies indicated that BBR/A35-loaded filomicelles were more stable when stored at 4 °C than at 25 °C. Compared with BBR-loaded filomicelles, A35-loaded filomicelles exhibited higher antitumor activity. Importantly, the in vitro cytotoxicity and stability of A35-loaded filomicelles evidenced the potential of drug-loaded filomicelles in the development of drug delivery systems.

Sodium deoxycholate mediated enhanced solubilization and stability of hydrophobic drug Clozapine in pluronic micelles

In this report, the solubilization behaviour of a hydrophobic drug Clozapine (CLZ) in micellar suspensions of pluronics having different hydrophilic lipophilic balance (HLB) ratios viz. P84, F127 and F108 in the absence and presence of bile salt sodium deoxycholate (SDC) has been studied. UV-Vis spectroscopy has been exploited to determine the solubilization capacity of the investigated micellar systems in terms of drug loading efficiency, average number of drug molecules solubilized per micelle (n_s), partition coefficient (P) and standard free energy of solubilization (∆G^°). The morphological and structural changes taking place in pluronics in different concentration regimes of SDC and with the addition of drug CLZ has been explored using dynamic light scattering (DLS) and small angle neutron scattering (SANS) measurements. The SANS results revealed that aggregation behaviour of pluronic-SDC mixed micelles gets improved in the presence of drug. The micropolarity measurements have been performed to shed light on the locus of solubilization of the drug in pure and mixed micellar systems. The compatibility between CLZ and drug carriers (pluronics and SDC) was confirmed using powder X-ray diffraction (PXRD) and Fourier transform infrared spectroscopy (FTIR) techniques. Among the investigated systems, P84-SDC mixed system was found to be highly efficient for CLZ loading. The long term stability data indicated that CLZ loaded P84-SDC mixed micellar formulation remained stable for 3months at room temperature. Further, it was revealed that the CLZ loaded P84-SDC mixed micelles are converted into CLZ loaded pure P84 micelles at 30-fold dilutions which remain stable up to 48-fold dilutions. The results from the present studies suggest that P84-SDC mixed micelles can serve as suitable delivery vehicles for hydrophobic drug CLZ.