Therapeutic efficacy of 2-methoxyestradiol microcrystals encapsulated within polyelectrolyte multilayers

Fine tuning of the pH-sensitivity of laponite-doxorubicin nanohybrids by polyelectrolyte multilayer coating

Despite the wide research done in the field, the development of advanced drug delivery systems with improved drug delivery properties and effective anticancer capability still remains a great challenge. Based on previous work that showed the potentialities of the nanoclay Laponite as a pH-sensitive doxorubicin (Dox) delivery vehicle, herein we report a simple method to modulate its extent of drug release at different pH values. This was achieved by alternate deposition of cationic poly(allylamine) hydrochloride and anionic poly(sodium styrene sulfonate) (PAH/PSS) polyelectrolytes over the surface of Dox-loaded Laponite nanoparticles using the electrostatic layer-by-layer (LbL) self-assembly approach. The successful formation of polyelectrolyte multilayer-coated Dox/Laponite systems was confirmed by Dynamic Light Scattering and zeta potential measurements. Systematic studies were performed to evaluate their drug release profiles and anticancer efficiency. Our results showed that the presence of the polyelectrolyte multilayers improved the sustained release properties of Laponite and allowed a fine tuning of the extension of drug release at neutral and acidic pH values. The cytotoxicity presented by polyelectrolyte multilayer-coated Dox/Laponite systems towards MCF-7 cells was in accordance with the drug delivery profiles. Furthermore, cellular uptake studies revealed that polyelectrolyte multilayer-coated Dox/Laponite nanoparticles can be effectively internalized by cells conducting to Dox accumulation in cell nucleus.

Recent developments in multilayered polymeric particles – from fabrication techniques to therapeutic formulations

Multilayered particles are emerging as a powerful platform in pharmaceutics, especially for targeted, triggered and sustained drug delivery.

Simultaneous enhanced diagnosis and photodynamic therapy of photosensitizer-doped perylene nanoparticles via doping, fluorescence resonance energy transfer, and antenna effect

We demonstrate a new strategy for preparing photosensitizer-doped perylene nanoparticles via doping, fluorescence resonance energy transfer, and antenna effect for simultaneous enhanced diagnosis and photodynamic therapy.

Bioluminescent microcapsules: applications in activating a photosensitizer

Bioluminescent microcapsules uploading D-luciferin have been fabricated by using the covalent assembly of firefly luciferase and alginate dialdehyde through a layer-by-layer technique. Such assembled microcapsules can produce visible light in the region of 520-680 nm, which can activate the photosensitizers rose bengal (RB) and hypocrellin B (HB) after adding ATP. The microcapsules uploading photosensitizers (RB or HB) have an obvious property to prevent the proliferation of tumor cells in the dark. The assembled bioluminescent microcapsules can be potentially used as photon donors for bioimaging, ATP detection, and photodynamic therapy.

Therapeutic promises of 2-methoxyestradiol and its drug disposition challenges

2-Methoxyestradiol (2MeO-E2) is an endogenous metabolite of estrogen which was initially considered to be inactive. During the last few decades it has been shown that 2MeO-E2 is a promising anticancer drug. In vitro experiments have demonstrated that it has several anticancer activities, and potential to alleviate hypertension, glomerulosclerosis, hypercholesterolemia, and other disorders. However, due to its low solubility and extensive glucuronidation, to achieve effective concentrations large doses of 2MeO-E2 would be required. Clinical studies reflected very high inter- and intrapatient variability and oral bioavailability of 1 to 2%. Thus, this review paper highlights the origin of this compound, its therapeutic promises, and possible mechanisms of action. It also discusses the pharmacokinetic properties of 2MeO-E2 as well as current developments to overcome low drug solubility and its extensive first pass metabolism.

Injectable delivery system of 2-methoxyestradiol for breast cancer therapy using biodegradable thermosensitive poly(organophosphazene) hydrogel

2-Methoxyestradiol (2-ME) has been reported to have antiangiogenic and antitumor activity. Its biomedical application is limited due to its poor water solubility resulting in its low bioavailability. Poly(organophosphazenes) containing l-isoleucine ethyl ester, ethyl-2-(O-glycyl)lactate, and α-amino-ω-methoxy-poly(ethylene glycol) 550 were synthesized having M(W) of 35-38 kDa and polydispersity index of 2.38-2.73. Using a viscometer, the thermosensitivity useful for locally injectable drug delivery was verified. The aqueous polymer solution showed a sol state at a low temperature and transformed to a gel state at body temperature. The polymer solution (10 wt%) enhanced the solubility of 2-ME by about 10(4) times compared to that of phosphate buffered saline. 2-ME was released from the hydrogel mainly by diffusion, hydrophobic interaction, and surface erosion of the matrix. This release profile could be confirmed through an in vitro release test as a function of polymers and the concentration of 2-ME in hydrogels. By monitoring tumor volume and CD31 immunohistochemical staining in mouse orthotopic breast tumor (MDA-MB-231) model, it was found that the hydrogel containing a relatively low concentration (15 mg/kg) of 2-ME showed the improved antitumor and antiangiogenic activity relative to the original formulation. This research suggests that the developed formulation of poly(organophosphazenes) may have injectable carrier potentials for 2-ME and other lipophilic drugs.

Influence of dendrimer surface charge on the bioactivity of 2-methoxyestradiol complexed with dendrimers

We report the complexation of a potential anticancer agent 2-methoxyestradiol (2-ME) with generation 5 (G5) poly(amidoamine) dendrimers having different surface functional groups for therapeutic applications. The complexation experiment shows that approximately 6-8 drug molecules can be complexed with one dendrimer molecule regardless the type of the dendrimer terminal groups. The bioactivity of 2-ME complexed with dendrimers was found to be significantly dependent on the surface charge of G5 dendrimers. In vitro cell biological assays show that amine, hydroxyl, and acetamide-terminated G5 dendrimers with positive, slightly positive, and close to neutral surface charges, respectively are able to deliver 2-ME to inhibit cancer cell growth. In contrast, 2-ME complexed with carboxyl-terminated G5 dendrimers with negative surface charges does not show its inherent bioactivity. Further molecular dynamics simulation studies show that the compact structure of carboxylated G5 dendrimers complexed with 2-ME does not allow the release of the drug molecules even at a pH of 5.0, which is the typical pH value in lysosome. Our findings indicate that the surface modification of dendrimers with different charges is crucial for the development of formulations of various anticancer drugs for therapeutic applications.

Polyelectrolyte multilayer-assisted immobilization of zero-valent iron nanoparticles onto polymer nanofibers for potential environmental applications

We report a facile approach to synthesizing and immobilizing zero-valent iron nanoparticles (ZVI NPs) onto polyelectrolyte (PE) multilayer-assembled electrospun polymer nanofibers for potential environmental applications. In this approach, negatively charged cellulose acetate (CA) nanofibers fabricated by electrospinning were assembled with multilayers of poly(diallyldimethylammonium chloride) (PDADMAC) and polyacrylic acid (PAA) through electrostatic layer-by-layer assembly. The formed PAA/PDADMAC multilayers onto CA nanofibers were then used as a nanoreactor to complex Fe(II) ions through the binding with the free carboxyl groups of PAA for subsequent reductive formation of ZVI NPs. Combined scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, Fourier transform infrared spectroscopy, and thermogravimetry analysis studies demonstrate that the ZVI NPs are successfully synthesized and uniformly distributed into the PE multilayers assembled onto the CA nanofibers. The produced hybrid nanofibrous mats containing ZVI NPs were found to exhibit superior capability to decolorize acid fuchsin, an organic dye in dyeing wastewater. We show that the loading capacity of ZVI NPs can be tuned by changing the number of PE layers and the cycles of binding/reduction process. Increasing the number of the binding/reduction cycles leads to a slight bigger size of the ZVI NPs, which is not beneficial for improving the reactivity of ZVI NPs. The present approach to synthesizing and immobilizing ZVI NPs onto polymer nanofibers opens a new avenue to fabricating various fiber-based composite materials with a high surface area to volume ratio for environmental, catalytic, and sensing applications.