Micelles, mixed micelles, and applications of polyoxypropylene (PPO)-polyoxyethylene (PEO)-polyoxypropylene (PPO) triblock polymers

Cytotoxic Effects of Nanoliposomal Cisplatin and Diallyl Disulfide on Breast Cancer and Lung Cancer Cell Lines

Dual drug delivery has become the choice of interest nowadays due to its increased therapeutic efficacy in targeting the tumor site precisely. As quoted in recent literature, it has been known to treat several cancers with an acute course of action. Even so, its use is restricted due to the drug’s low pharmacological activity, which leads to poor bioavailability and increases first-pass metabolism. To overcome these issues, a drug delivery system using nanomaterials which would not only encapsulate the drugs of interest but also carry them to the target site of action is needed. Given all these attributes, we have formulated dual drug-loaded nanoliposomes with cisplatin (cis-diamminedichloroplatinum(II) (CDDP)), an effective anti-cancer drug, and diallyl disulfide (DADS), an organosulfur compound derived from garlic. The CDDP and DADS-loaded nanoliposomes (Lipo-CDDP/DADS) exhibited better physical characteristics such as size, zeta potential, polydispersity index, spherical shape, optimal stability, and satisfactory encapsulation percentage. The in vitro anti-cancer activity against MDA-MB-231 and A549 cell lines revealed that Lipo-CDDP/DADS showed significant efficacy against the cancer cell lines, depicted through cell nucleus staining. We conclude that Lipo-CDDP/DADS hold exceptional pharmacological properties with better anti-cancer activity and would serve as a promising formulation to treat various cancers.

Meso- and Macroporous Polymer Gels for Efficient Adsorption of Block Copolymer Surfactants

An understanding of surfactant adsorption at solid-liquid interfaces is important for solving many technological problems. This work evaluates surfactant adsorption abilities of high surface area (200-600 m²/g), high porosity (>90%), hierarchically structured open pore polymer gels. Specifically, the interactions of a nonionic block copolymer surfactant, poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO), with three polymer gels, namely, syndiotactic polystyrene (sPS), polyimide (PI), and polyurea (PUA) offering different surface energy values, are evaluated at surfactant concentrations below and well above the critical micelle concentration (CMC). Two distinct surfactant adsorption behaviors are identified from the surface tension and nuclear magnetic resonance data. At concentrations below CMC, the surfactant molecules adsorb as a monolayer on polymer strands, inferred from the Langmuir-type adsorption isotherm, with the adsorbed amount increasing with the specific surface area of the polymer gel. The study reports for the first time that the gels show a strong surfactant adsorption above CMC, with the effective surfactant concentration in the gel reaching several folds of the CMC values. The effective surfactant concentration in the gel is analyzed using surfactant micelle size, polymer surface energy, and pore size of the gel. The findings of this study may have strong implications in liquid-liquid separation problems and in the removal of small dye molecules, heavy metal ions, and living organisms from aqueous streams.

Photo-Cross-Linkable Human Albumin Colloidal Gels Facilitate In Vivo Vascular Integration for Regenerative Medicine

Biodegradable cellular and acellular scaffolds have great potential to regenerate damaged tissues or organs by creating a proper extracellular matrix (ECM) capable of recruiting endogenous cells to support cellular ingrowth. However, since hydrogel-based scaffolds normally degrade through surface erosion, cell migration and ingrowth into scaffolds might be inhibited early in the implantation. This could result in insufficient de novo tissue formation in the injured area. To address these challenges, continuous and microsized strand-like networks could be incorporated into scaffolds to guide and recruit endogenous cells in rapid manner. Fabrication of such microarchitectures in scaffolds is often a laborious and time-consuming process and could compromise the structural integrity of the scaffold or impact cell viability. Here, we have developed a fast single-step approach to fabricate colloidal hydrogels, which are made up of randomly packed human serum albumin-based photo-cross-linkable microparticles with continuous internal networks of microscale voids. The human serum albumin conjugated with methacrylic groups were assembled to microsized aggregates for achieving unique porous structures inside the colloidal gels. The albumin hydrogels showed tunable mechanical properties such as elastic modulus, porosity, and biodegradability, providing a suitable ECM for various cells such as cardiomyoblasts and endothelial cells. In addition, the encapsulated cells within the hydrogel showed improved cell retention and increased survivability in vitro. Microporous structures of the colloidal gels can serve as a guide for the infiltration of host cells upon implantation, achieving rapid recruitment of hematopoietic cells and, ultimately, enhancing the tissue regeneration capacity of implanted scaffolds.

Injectable thermoresponsive gels offer sustained dual release of bupivacaine hydrochloride and ketorolac tromethamine for up to two weeks

Bupivacaine and ketorolac are commonly used in combination to reduce perioperative pain. This study aimed to develop and characterize an injectable system that offers simultaneous and prolonged release of bupivacaine and ketorolac. Formulations were prepared using poloxamer 407 with increasing concentrations of poloxamer 188 and sodium chloride. Small Angle X-ray Scattering (SAXS) experiments demonstrated that the poloxamers form gels with a cubic lattice arrangement regardless of the matrix composition, whereas the system porosity is driven by poloxamers concentration. Drug loading slightly reduced the intermicellar spacing. Fourier transform infrared spectroscopy and thermal analysis suggested electrostatic interactions between the loaded drugs and poloxamers. Mechanical and rheological studies confirmed the formulations exhibit Newtonian-like flow at room temperature followed by a transition to a viscous gel at body temperature. Importantly, the developed formulations demonstrated steady and sustained release of both bupivacaine and ketorolac over two weeks. Sodium chloride reduced the initial burst release over the first six hours for BH, from 8.6 ± 0.18% to 1.6 ± 0.11%, and KT, from 7.7 ± 0.27% to 1.5 ± 0.10%. Hence, poloxamer-based thermoresponsive gelling systems are promising delivery platforms for the sustained delivery of bupivacaine and ketorolac, with potential clinical benefits for managing perioperative pain.

Anti-Aβ-scFv-loaded polymeric nano-micelles with enhanced plasma stability

OBJECTIVES

Immunotherapy using recombinant monoclonal antibodies specifically Anti-amyloid-beta (Anti-Aβ) scFv is envisaged as an appropriate therapeutic for Alzheimer through reduction of amyloid-beta aggregation. The solubilization of therapeutics using polymeric micelles facilitates an improved bioavailability and extended blood half-life. In this study, the optimum production condition for Anti-amyloid-beta (Anti-Aβ) scFv was obtained. To increase the stability of plasma, Anti-Aβ-loaded polymeric micelles were synthesized.

METHODS

Escherichia coli SHuffle expression strain was used and purified by Ni-NTA. Pluronics P85 and F127 micelles were used for the Anti-Aβ delivery and were characterized in terms of morphology, drug loading and drug release in phosphate buffer and artificial cerebrospinal fluid. The stability profile was quantified at 4°C over a 30 days storage period. The stability in human plasma was also evaluated.

KEY FINDINGS

Proteins expressed in SHuffle resulted in increased levels of protein expression and solubility. Low critical micelle concentration value and high micelle encapsulation efficiency (<200 nm) achieved via direct dissolution method. Anti-Aβ-loaded micelles were around 2.2-fold more stable than Anti-Aβ in plasma solution. A sustained in-vitro release of Anti-Aβ from micelles was observed.

CONCLUSIONS

Results confirmed that Pluronic-micelles pose benefits as a nano-carrier to increase the stability of Anti-Aβ scFvin in the plasma.

Mucoadhesive Poloxamer-Based Hydrogels for the Release of HP-β-CD-Complexed Dexamethasone in the Treatment of Buccal Diseases

Oral lichen planus (OLP) is an ongoing and chronic inflammatory disease affecting the mucous membrane of the oral cavity. Currently, the treatment of choice consists in the direct application into the buccal cavity of semisolid formulations containing a corticosteroid molecule to decrease inflammatory signs and symptoms. However, this administration route has shown various disadvantages limiting its clinical use and efficacy. Indeed, the frequency of application and the incorrect use of the preparation may lead to a poor efficacy and limit the treatment compliance. Furthermore, the saliva clearance and the mechanical stress present in the buccal cavity also involve a decrease in the mucosal exposure to the drug. In this context, the design of a new pharmaceutical formulation, containing a steroidal anti-inflammatory, mucoadhesive, sprayable and exhibiting a sustained and controlled release seems to be suitable to overcome the main limitations of the existing pharmaceutical dosage forms. The present work reports the formulation, optimization and evaluation of the mucoadhesive and release properties of a poloxamer 407 thermosensitive hydrogel containing a poorly water-soluble corticosteroid, dexamethasone acetate (DMA), threaded into hydroxypropyl-beta-cyclodextrin (HP-β-CD) molecules. Firstly, physicochemical properties were assessed to ensure suitable complexation of DMA into HP-β-CD cavities. Then, rheological properties, in the presence and absence of various mucoadhesive agents, were determined and optimized. The hydration ratio (0.218-0.191), the poloxamer 407 (15-17 wt%) percentage and liquid-cyclodextrin state were optimized as a function of the gelation transition temperature, viscoelastic behavior and dynamic flow viscosity. Deformation and resistance properties were evaluated in the presence of various mucoadhesive compounds, being the sodium alginate and xanthan gum the most suitable to improve adhesion and mucoadhesion properties. Xanthan gum was shown as the best agent prolonging the hydrogel retention time up to 45 min. Furthermore, xanthan gum has been found as a relevant polymer matrix controlling drug release by diffusion and swelling processes in order to achieve therapeutic concentration for prolonged periods of time.

Lectin Protein as a Promising Component to Functionalize Micelles, Liposomes and Lipid NPs against Coronavirus

The outbreak of a novel strain coronavirus as the causative agent of COVID-19 pneumonia, first identified in Wuhan, China in December 2019, has resulted in considerable focus on virulence abilities of coronavirus. Lectins are natural proteins with the ability to bind specific carbohydrates related to various microorganisms, including viruses, bacteria, fungi and parasites. Lectins have the ability to agglutinate and neutralize these pathogeneses. The delivery of the encapsulated antiviral agents or vaccines across the cell membrane can be possible by functionalized micellar and liposomal formulations. In this mini-review, recent advances and challenges related to important lectins with inhibition activities against coronaviruses are presented to obtain a novel viewpoint of microformulations or nanoformulations by micellar and liposomal cell-binding carriers.

Surfactant-Mediated and Morphology-Controlled Nanostructured LiFePO4/Carbon Composite as a Promising Cathode Material for Li-Ion Batteries

The synthesis of morphology-controlled carbon-coated nanostructured LiFePO4 (LFP/Carbon) cathode materials by surfactant-assisted hydrothermal method using block copolymers is reported. The resulting nanocrystalline high surface area materials were coated with carbon and designated as LFP/C123 and LFP/C311. All the materials were systematically characterized by various analytical, spectroscopic and imaging techniques. The reverse structure of the surfactant Pluronic® 31R1 (PPO-PEO-PPO) in comparison to Pluronic® P123 (PEO-PPO-PEO) played a vital role in controlling the particle size and morphology which in turn ameliorate the electrochemical performance in terms of reversible specific capacity (163 mAh g-1 and 140 mAh g-1 at 0.1 C for LFP/C311 and LFP/C123, respectively). In addition, LFP/C311 demonstrated excellent electrochemical performance including lower charge transfer resistance (146.3 Ω) and excellent cycling stability (95 % capacity retention at 1 C after 100 cycles) and high rate capability (163.2 mAh g-1 at 0.1 C; 147.1 mAh g-1 at 1 C). The better performance of the former is attributed to LFP nanoparticles (<50 nm) with a specific spindle-shaped morphology. Further, we have also evaluated the electrode performance with the use of both PVDF and CMC binders employed for the electrode fabrication.

Self-Assembling Raloxifene Loaded Mixed Micelles: Formulation Optimization, In Vitro Cytotoxicity and In Vivo Pharmacokinetics

Raloxifene (RLX) has been strongly recommended for postmenopausal women at high risk of invasive breast cancer and for prevention of osteoporosis. However, low aqueous solubility and reduced bioavailability hinder its clinical application. The objective of this study was to explore the potential of RLX loaded mixed micelles (RLX-MM) using Pluronic F68 and Gelucire 44/14 for enhanced bioavailability and improved anticancer activity on human breast cancer cell line (MCF-7). RLX-MM were prepared by solvent evaporation method and optimized using 3² factorial design. The average size, entrapment efficiency and zeta potential of the optimized formulation were found to be 190 ± 3.3 nm, 79 ± 1.3%, 13 ± 0.8 mV, respectively. In vitro study demonstrated 74.68% drug release from RLX-MM in comparison to 42.49% drug release from RLX dispersion. According to the in vitro cytotoxicity assay, GI₅₀ values on MCF-7 breast cancer cell line for RLX-MM and free RLX were found to be 22.5 and 94.71 μg/mL, respectively. Significant improvement (P < 0.05) in the anticancer activity on MCF-7 cell line was observed in RLX-MM over RLX pure drug. Additionally, oral bioavailability of RLX-MM was improved by 1.5-fold over free RLX when administered in female Wistar rats. Incorporation of RLX in the hydrophobic core and improved solubility of the drug due to hydrophilic shell attributed to the enhanced cytotoxicity and bioavailability of RLX-MM. This research establishes the potential of RLX loaded mixed micelles of Pluronic F68 and Gelucire 44/14 for improved bioavailability and anticancer activity on MCF-7 cell line.

Mesoporous 45S5 bioactive glass: synthesis, in vitro dissolution and biomineralization behavior

The development of a new generation of biomaterials includes a sol-gel process to obtain glass foams, which is a well established method for CaO-SiO₂-P₂O₅ compositions, but is not yet recognized for Bioglass® containing sodium oxide. In this study, we report, for the first time, the synthesis of a mesoporous 45S5 bioactive glass with superior textural characteristics and its in vitro dissolution and biomineralization behavior. Wormhole-like bioactive mesostructured 45S5 glass has been synthesized by an acid assisted sol-gel method followed by an evaporation induced self-assembly process. The virgin mesoporous 45S5 bioactive glass has been characterized by various analytical methods before and after soaking in simulated body fluid (SBF). The factors affecting the glass formation have been discussed in terms of the critical micelle concentration (CMC) at a particular temperature followed by a specified time interval. In vitro studies on the mesostructured 45S5 glass sample reveal the rapid formation of carbonated hydroxyapatite (HCA) with nano sized crystals. The mesostructured glass showed an excellent cell proliferation response without toxicity up to the concentration of 50 μg ml^-1. Furthermore, we show that the 45S5 glass with superior textural parameters is extremely useful within the family of bioactive materials as it has accelerated formation kinetics of the apatite phase as compared to other bioactive glass compositions.

Nanostructured DPA-MPC-DPA triblock copolymer gel for controlled drug release of ketoprofen and spironolactone

OBJECTIVE

Uncontrolled rapid release of drugs can reduce their therapeutic efficacy and cause undesirable toxicity; however, controlled release from reservoir materials helps overcome this issue. The aims of this study were to determine the release profiles of ketoprofen and spironolactone from a pH-responsive self-assembling DPA-MPC-DPA triblock copolymer gel and elucidate underlying physiochemical properties.

METHODS

Drug release profiles from DPA₅₀ -MPC₂₅₀ -DPA₅₀ gel (pH 7.5), over 32 h (37 °C), were determined using UV-Vis spectroscopy. Nanoparticle size was measured by dynamic light scattering (DLS) and critical micelle concentration (CMC) by pyrene fluorescence. Polymer gel viscosity was examined via rheology, nanoparticle morphology investigated using scanning transmission electron microscopy (STEM) and the gel matrix observed using cryo-scanning electron microscopy (Cryo-SEM).

KEY FINDINGS

DPA₅₀ -MPC₂₅₀ -DPA₅₀ copolymer (15% w/v) formed a free-standing gel (pH 7.5) that controlled drug release relative to free drugs. The copolymer possessed a low CMC, nanoparticle size increased with copolymer concentration, and DLS data were consistent with STEM. The gel displayed thermostable viscosity at physiological temperatures, and the gel matrix was a nanostructured aggregation of smaller nanoparticles.

CONCLUSIONS

The DPA₅₀ -MPC₂₅₀ -DPA₅₀ copolymer gel could be used as a drug delivery system to provide the controlled drug release of ketoprofen and spironolactone.

Stability effect of cholesterol-poly(acrylic acid) in a stimuli-responsive polymer-liposome complex obtained from soybean lecithin for controlled drug delivery

The development of polymer-liposome complexes (PLCs), in particular for biomedical applications, has grown significantly in the last decades. The importance of these studies comes from the emerging need in finding intelligent controlled release systems, more predictable, effective and selective, for applications in several areas, such as treatment and/or diagnosis of cancer, neurological, dermatological, ophthalmic and orthopedic diseases, gene therapy, cosmetic treatments, and food engineering. This work reports the development and characterization of a pH sensitive system for controlled release based on PLCs. The selected hydrophilic polymer was poly(acrylic acid) (PAA) synthesized by atom transfer radical polymerization (ATRP) with a cholesterol (CHO) end-group to improve the anchoring of the polymer into the lipid bilayer. The polymer was incorporated into liposomes formulated from soybean lecithin and stearylamine, with different stearylamine/phospholipid and polymer/phospholipid ratios (5, 10 and 20%). The developed PLCs were characterized in terms of particle size, polydispersity, zeta potential, release profiles, and encapsulation efficiency. Cell viability studies were performed to assess the cytotoxic potential of PLCs. The results showed that the liposomal formulation with 5% of stearylamine and 10% of polymer positively contribute to the stabilization of the complexes. Afterwards, the carboxylic acid groups of the polymer present at the surface of the liposomes were crosslinked and the same parameters analyzed. The crosslinked complexes showed to be more stable at physiologic conditions. In addition, the release profiles at different pHs (2-12) revealed that the obtained complexes released all their content at acidic conditions. In summary, the main accomplishments of this work are: (i) innovative synthesis of cholesterol-poly(acrylic acid) (CHO-PAA) by ATRP; (ii) stabilization of the liposomal formulation by incorporation of stearylamine and CHO-PAA; (iii) new approach for CHO-PAA crosslinking, resulting in more stable PLCs at physiological conditions; (iv) destabilization of PLCs upon slight changes of pH, showing their pH sensitivity; and (v) the PLCs do not exhibit cellular toxicity.

Utilizing an aggregate forming microenvironment sensitive coumarin–cholesterol conjugate as a sensor of pluronic organization and micro-polarity

A new fluorescent cholesterol molecular probe, 3-acetyl-7-(diethylamino)-2H-chromen-2-one attached cholesterol (Cum–Chl), has recently been introduced as a reporter of micro-heterogeneous media.

TPGS-g-PLGA/Pluronic F68 mixed micelles for tanshinone IIA delivery in cancer therapy

Tanshinone IIA (TAN) has few clinical applications for anti-cancer therapy mainly due to its high lipophicity, low cellular uptake, and poor bioavailability. To improve the anti-cancer effect and bioavailability of TAN, we developed a mixed micelle system constituted with D-α-tocopheryl polyethylene glycol succinate-graft-poly(D,L-lactide-co-glycolide) (TPGS-g-PLGA) copolymer and Pluronic F68. TAN was encapsulated in the TPGS-g-PLGA/Pluronic F68 mixed micelles by using the thin film hydration technology optimized by the central composite design/response surface method (CCD/RSM). TAN-loaded mixed micelles were highly stable in the presence or absence of bovine serum albumin (BSA) and achieved sustained drug release in vitro. Compared with free TAN, TAN mixed micelles had higher cytotoxicity and pro-apoptotic effects against human hepatocellular carcinoma HepG2 cells. The significant enhancement on pro-apoptosis by TAN micelles was evidenced by increased chromosome condensation, mitochondria membrane potential loss, cell apoptosis, and cleavages of caspase-3 and PARP. Furthermore, pharmacokinetic studies revealed that TAN mixed micelles significantly prolonged the circulation time and improved bioavailability of TAN in rats. These results demonstrated that TAN-loaded TPGS-g-PLGA/F68 mixed micelles are an effective strategy to deliver TAN for cancer therapy.