In-vitro evaluation of cytotoxic and antioxidant properties of drugs solubilized in EO-PO star block copolymer micelles

Hyperoside-loaded TPGs/mPEG-PDLLA self-assembled polymeric micelles: preparation, characterization and in vitro/in vivo evaluation

Hyperoside (Hyp) self-assembled polymeric micelles (Hyp-PMs) were purposely developed to enhance aqueous solubility, in vivo availability and anti-oxidative effect of Hyp. In preparing Hyp-PMs, we employed the thin film dispersion method with the micelles consisting of TPGs and mPEG2000-PDLLA3000. The particle size, polydispersity index and zeta potential of Hyp-PMs were 67.42 ± 1.44 nm, 0.229 ± 0.015 and -18.67 ± 0.576 mV, respectively, coupled with high encapsulation efficiency (EE)of 90.63 ± 1.45% and drug loading (DL) of 6.97 ± 1.56%. Furthermore, the value of critical micelle concentration (CMC) was quite low, which indicated good stability and improved self-assembly ability of Hyp-PMs. Also, trend of in vitro Hyp release from Hyp-PMs demonstrated enhanced solubility of Hyp. Similarly, in comparison with free Hyp, oral bioavailability of Hyp-PMs was improved (about 8 folds) whilst half-life of Hyp-PMs was extended (about 3 folds). In vitro anti-oxidative effect showed obvious strong scavenging DPPH capability of Hyp-PMs, which may be attributed to its smaller size and better solubility. Altogether, Hyp-PMs may serve as a possible strategy to potentially enhance aqueous solubility, bioavailability and anti-oxidative effect of Hyp, which may play a key role in Hyp application in the pharmaceutical industries.

Micellar assembly leading to structural growth/transition in normal and reverse Tetronics® in single and mixed solution environment

This study scrutinizes the self-association of ethylene oxide (EO)-propylene oxide (PO)-based star-shaped block copolymers as normal Tetronic® (T904) and reverse Tetronic® R (T90R4) with varying molecular characteristics and different hydrophilic-hydrophobic ratios in an aqueous solution environment. These thermo-responsive solutions appear clear, transparent or bluish up to 10%w/v, which anticipated the probable transition of unimers to spherical or ellipsoidal micelles which is complemented by scattering experiments. In a single-solution environment, 10%w/v T904 formed star-shaped micelles at ambient temperature and exhibited a micellar growth/transition with temperature ageing. While 10%w/v T90R4 exists as unimers or a Gaussian coil over a wide range of temperature. Very interestingly, close to the cloud point (CP) flower-shaped spherical and ellipsoidal micelles were formed. A similar proposed micellar scheme was also examined for mixed systems T904 : T90R4 in varying ratios (1 : 0, 3 : 1, 1 : 1, 1 : 3 and 0 : 1) giving an account to the solution behavior of the mixtures. An amalgamation of dynamic light scattering (DLS) and small-angle neutron scattering (SANS) techniques achieved the thorough extraction of the structural parameters of the micellar system. The hydrodynamic diameter (D_h) of the micelles with temperature variation was evaluated from dynamic light scattering (DLS) while the structure factor of the micelles was found by employing small-angle neutron scattering (SANS). Furthermore, the single and mixed micellar systems were quantitatively and qualitatively examined for anticancer drug solubilization using UV-vis spectroscopy for their superior use as potential nanocargos.

Molecular mechanism underlying the effects of temperature and pH on the size and surface charge of octenylsuccinated oat β-glucan aggregates

Environmental temperature and pH induced significant changes in the size and surface charge (ζ) of octenylsuccinated oat β-glucan aggregates. The underlying mechanisms were explored by using ¹H-NMR, fluorescence spectra, thermodynamic analysis, and SAXS. At pH 6.5, the size decreased with temperature while ζ continuously increased. With increasing pH at 293 K, parabolic and U-shaped trends were observed in the size and ζ, peaking at pH 8.5 and 6.5, respectively. At any tested pH, the size decreased with temperature. Overall, ζ significantly increased with temperature at each pH. As temperature increased, the compactness of hydrophobic-domains increased while the compactness of hydrophilic-domains decreased. In an acidic environment, both the compactness increased with decreasing pH, but in an alkaline environment, they decreased with pH. The compactness changes were co-driven by enthalpy and entropy and corresponded to changes in the hydrophobic interactions in hydrophobic-domains, hydrogen bonds in hydrophilic-domains and electrostatic repulsions among octenylsuccinate molecules.

Poly(ethylene glycol) crosslinked multi-armed poly(ε-benzyloxycarbonyl-L-lysine)s as super-amphiphiles: Synthesis, self-assembly, and evaluation as efficient delivery systems for poorly water-soluble drugs

Polymeric micelles with high thermodynamic stability and loading capacity are of tremendous significance for their potential applications in drug delivery. In the present study, super-amphiphiles in the form of poly(ethylene glycol)-crosslinked multi-armed polyethylenimine-g-poly(ε-benzyloxycarbonyl-L-lysine)s (PEZ-alt-PEG) were designed, synthesized, and optimized as nanocarriers for hydrophobic drugs. In an aqueous solution, the copolymer PEZ-alt-PEG self-assembled into sub-100-nm spherical shell crosslinked micelles with low toxicity in vitro and in vivo. The crosslinked super-amphiphilic structure of PEZ-alt-PEG could not only enhance the thermodynamic stability of polymeric micelles, but it could also significantly improve the loading capacity of hydrophobic drugs, such as curcumin (CUR). CUR-loaded PEZ-alt-PEG micelles could mediate effective drug delivery with sustained and complete CUR release. The use of PEZ-alt-PEG micellar nanocarriers remarkably improved the cellular uptake of CUR and therefore exhibited effective inhibitory activity on the growth of human hepatoma (HepG2) cells. Compared to free CUR, CUR-loaded polymeric micelles significantly accelerated the apoptosis rate of HepG2 cells. Therefore, PEZ-alt-PEG polymeric micelles, with their high thermodynamic stability, high drug-loading capacity, enhanced drug uptake and improved pharmacodynamic effects, could serve as efficient and promising nanocarriers for poorly water-soluble drugs.