Fabrication and characterization of self-assembled whey protein isolate/short linear glucan core-shell nanoparticles for sustained release of curcumin

The aim of this research was to prepare a bistratal nanocomplex with a high loading capacity (LC) and harsh environment stability for controlled release of curcumin (Cur) in gastrointestinal conditions. Whey protein isolate (WPI)/short linear glucan (SLG) core-shell nanoparticles were fabricated by self-assembly for the delivery of Cur. The results showed that Cur@WPI@SLG nanoparticles had a relatively high LC (12.89 %) and small particle size (89.4 nm). The nanocomplex remained relatively stable in extreme pH conditions (2-4 and 8-10), high temperatures (60-70 °C), and ionic strength (<400 mM). Core-shell nanostructures facilitated the sustained release of Cur in simulated gastrointestinal conditions. In addition, the nanocomplex had little cytotoxicity at high concentrations, yet significantly enhanced the DPPH scavenging activity and reducing power of Cur. This delivery system will significantly improve the sustained release effect of Cur and broaden the application of hydrophobic nutrients in foods.

A novel immunochemotherapy based on targeting of cyclooxygenase and induction of immunogenic cell death

Cyclooxygenase (COX) plays a crucial role in the "inflammogenesis of cancer", which leads to tumor progression, metastasis, and immunotherapy resistance. Therefore, reducing "inflammogenesis" by COX inhibition may be a key perspective for cancer therapy. However, the role of tumor-derived COX in the actions of COX inhibitors remains incompletely understood. In this study, applying "old drug new tricks" to repurpose 5-aminosalicylic acid (5-ASA), a COX inhibitor, we examined the effect of 5-ASA, alone or in combination with doxorubicin (DOX), in several cancer cell lines with different levels of COX expression. To facilitate the evaluation of the combination effect on tumors in vivo, a new micellar carrier based on PEG-b-PNHS polymer-conjugated 5-ASA (PASA) was developed to enhance codelivery of 5-ASA and DOX. Folate was also introduced to the polymer (folate-PEG-NH₂-conjugated PASA (FASA)) to further improve delivery to tumors via targeting both tumor cells and tumor macrophages. An unprecedented high DOX loading capacity of 42.28% was achieved through various mechanisms of carrier/drug interactions. FASA was highly effective in targeting to and in inhibiting the growth of both 4T1.2 and CT26 tumors in BALB/c mice. However, FASA was more effective in CT26 tumor that has a high level of COX expression. Codelivery of DOX via PASA and FASA led to a further improvement in antitumor activity. Mechanistic studies suggest that inhibition of COX in vivo led to a more active tumor immune microenvironment. Interestingly, treatment with FASA led to upregulation of PD-1 on T cells, likely due to repressing the inhibitory effect of prostaglandin E2 (PGE₂) on PD-1 expression on T cells. Combination of FASA/DOX with anti-PD-1 antibody led to a drastic improvement in the overall antitumor activity including regression of some established tumors at a suboptimal dose of FASA/DOX. Our data suggest that FASA/DOX may represent a new and effective immunochemotherapy for various types of cancers, particularly those cancers with high levels of COX expression.

Glutathione-sensitive hollow mesoporous silica nanoparticles for controlled drug delivery

Tunable glutathione (GSH)-sensitive hollow mesoporous silica nanoparticles (HMSiO2 NPs) were developed using a structural difference-based selective etching strategy. These organosilica hollow nanoparticles contained disulfide linkages (S-S) in the outer shell which were degraded by GSH. The particles were compared with their nonGSH-sensitive tetraethyl orthosilicate (TEOS) HMSiO2 counterparts in terms of their synthesis method, characterization, doxorubicin (DOX) release profile, and in vitro cytotoxicity in MCF-7 breast cancer cells. Transmission electron microscopy (TEM) of the particles indicated that the fabricated HMSiO2 NPs had an average diameter of 130 ± 5 nm. Thermogravimetric analysis (TGA) revealed that GSH-sensitive particles had approximately 5.3% more weight loss than TEOS HMSiO2 NPs. Zeta potential of these redox-responsive particles was -23 ± 1 mV at pH 6 in deionized (DI) water. Nitrogen adsorption-desorption isotherm revealed that the surface area of the hollow mesoporous nanoreservoirs was roughly 446 ± 6 m2 g-1 and the average diameter of the pores was 2.3 ± 0.5 nm. TEM images suggest that the nanoparticles started to lose mass integrity from Day 1. The particles showed a high loading capacity for DOX (8.9 ± 0.5%) as a model drug, due to the large voids existing in the hollow structures. Approximately 58% of the incorporated DOX released within 14 days in phosphate buffered saline (PBS) at pH 6 and in the presence of 10 mM of GSH, mimicking intracellular tumor microenvironment while release from TEOS HMSiO2 NPs was only c.a. 18%. The uptake of these hollow nanospheres by MCF-7 cells and RAW 264.7 macrophages was evaluated using TEM and confocal microscopy. The nanospheres were shown to accumulate in the endolysosomal compartments after incubation for 24 h with the maximum uptake of c.a. 2.1 ± 0.3% and 5.2 ± 0.4%, respectively. Cytotoxicity of the nanospheres was investigated using CCK-8 assay. Results indicate that intact hollow particles (both GSH-sensitive and TEOS HMSiO2 NPs) were nontoxic to MCF-7 cells after incubation for 24 h within the concentration range of 0-1000 μg ml-1. DOX-loaded GSH-sensitive nanospheres containing 6 μg ml-1 of DOX killed c.a. 51% of MCF-7 cells after 24 h while TEOS HMSiO2 NPs killed c.a. 20% with the difference being statistically significant. Finally, cytotoxicity data in RAW 264.7 macrophages and NIH 3 T3 fibroblasts shows that intact GSH-sensitive HMSiO2 NPs did not show any toxic effects on these cells with the concentrations equal or <125 μg ml-1.

Riboflavin-containing telodendrimer nanocarriers for efficient doxorubicin delivery: High loading capacity, increased stability, and improved anticancer efficacy

We have developed two linear-dendritic telodendrimers (TDs) with rational design using amphiphilic riboflavin (Rf) as building blocks for efficient doxorubicin (DOX) delivery. Micellar TD nanoparticles (NPs) are composed of a hydrophilic polyethylene glycol (PEG) shell and a Rf-containing affinitive core for DOX encapsulation. Strong DOX-Rf interactions and amphiphilic Rf structure render these nanocarriers with an ultra-high DOX loading capacity (>1/1, DOX/TD, w/w), ∼100% loading efficiency, the sustained drug release and the optimal particle sizes (20-40 nm) for efficient tumor-targeted drug delivery. These nanoformulations significantly prolonged DOX circulation time in the blood without the accelerated clearance observed after multiple injections. DOX-TDs target several types of tumors efficiently in vivo, e.g. Raji lymphoma, MDA-MB-231 breast cancer, and SKOV-3 ovarian cancer. In vivo maximum tolerated dose (MTD) of DOX was increased by 2-2.5 folds for the nanoformulations in mice relative to those of free DOX and Doxil^®. These nanoformulations significantly inhibited tumor growth and prolonged survival of mice bearing SKOV-3 ovarian cancer xenografts. In summary, Rf-containing nanoformulations with high DOX loading capacity, improved stability and efficient tumor targeting lead to superior antitumor efficacy, which merit the further development for clinical application.

Mercaptan acids modified amphiphilic copolymers for efficient loading and release of doxorubicin

In this paper, four different kinds of mercaptan acids modified amphiphilic copolymers mPEG-b-PATMC-g-SRCOOH (R=CH₂, CH₂CH₂, (CH₂)₁₀ and CH(COOH)CH₂) were successfully synthesized by thiol-ene "click" reaction between pendent carbon-carbon double bonds of PEG-b-PATMC and thiol groups of thioglycolic acid, 3-mercaptopropionic acid, 11-mercaptoundecanoic acid or 2-mercaptosuccinic acid. DLS and TEM measurements showed that all the mPEG-b-PATMC-g-SRCOOH copolymers could self-assemble to form micelles which dispersed in spherical shape with nano-size before and after DOX loading. The positively-charged DOX could effectively load into copolymer micelles via synergistic hydrophobic and electrostatic interactions. All DOX-loaded mPEG-b-PATMC-g-SRCOOH micelles displayed sustained drug release behavior without an initial burst which could be further adjusted by the conditions of ionic strength and pH. Especially in the case of mPEG-b-PATMC-g-S(CH₂)₁₀COOH (P3) micelles, the suitable hydrophobility and charge density were not only beneficial to improve the DOX-loading efficiency, they were also good for obtaining smaller particle size, higher micelle stability and more timely drug delivery. Confocal laser scanning microscopy (CLSM) and MTT assays further demonstrated efficient cellular uptake of DOX delivered by mPEG-b-PATMC-g-SRCOOH micelles and potent cytotoxic activity against cancer cells.