Lipase is essential for the study of in vitro release kinetics from organogels

Engineering Lipid Spherulites for the Sustained Release of Highly Dosed Small Hydrophilic Compounds

Currently, there is a lack of parenteral sustained release formulations for the delivery of highly dosed small hydrophilic drugs. Therefore, parenteral lipid spherulites are engineered capable of entrapping large amounts of such compounds and spontaneously releasing them in a sustained fashion. A library of spherulites is prepared with a simple green process, using phosphatidylcholine (PC) and/or phosphatidylethanolamine (PE), nonionic surfactants and water. The vesicle formulations exhibiting appropriate size distribution and morphology are selected and loaded with 4,6-di-O-(methoxy-diethyleneglycol)-myo-inositol-1,2,3,5-tetrakis(phosphate), ((OEG₂ )₂ -IP4), an inositol phosphate derivative currently under clinical evaluation for the treatment of aortic valve stenosis. The loading efficiency of spherulites is up to 12.5-fold higher than that of liposomes produced with the same materials. While the PC-containing vesicles showed high stability, the PE spherulites gradually lost their multilayer organization upon dilution, triggering the active pharmaceutical ingredient (API) release over time. In vitro experiments and pharmacokinetic studies in rats demonstrated the ability of PE spherulites to increase the systemic exposure of (OEG₂ )₂ -IP4 up to 3.1-fold after subcutaneous injection, and to completely release their payload within 3-4 d. In conclusion, PE spherulites represent a promising lipid platform for the extravascular parenteral administration of highly dosed small hydrophilic drugs.

Dual Delivery of Gemcitabine and Paclitaxel by Wet-Spun Coaxial Fibers Induces Pancreatic Ductal Adenocarcinoma Cell Death, Reduces Tumor Volume, and Sensitizes Cells to Radiation

Pancreatic ductal adenocarcinoma (PDAC) has a dismal prognosis, with surgical resection of the tumor in conjunction with systemic chemotherapy the only potential curative therapy. Up to 80% of diagnosed cases are deemed unresectable, prompting the need for alternative treatment approaches. Herein, coaxial polymeric fibers loaded with two chemotherapeutic agents, gemcitabine (Gem) and paclitaxel (Ptx), are fabricated to investigate the effect of local drug delivery on PDAC cell growth in vitro and in vivo. A wet-spinning fabrication method to form a coaxial fiber with a polycaprolactone shell and alginate core loaded with Ptx and Gem, respectively, is used. In vitro, Gem+Ptx fibers display significant cytotoxicity as well as radiosensitizing properties toward PDAC cell lines greater than the equivalent free drugs, which may be attributed to a radiosensitizing effect of the polymers. In vivo studies assessing Gem+Ptx fiber efficacy found that Gem+Ptx fibers reduce tumor volume in a xenograft mouse model of PDAC. Importantly, no difference in mouse weight, circulating cytokines, or liver function is observed in mice treated with Gem+Ptx fibers compared to the empty fiber controls confirming the safety of the implant approach. With further development, Gem+Ptx fibers can improve the treatment of unresectable PDAC in the future.

A Cyclodextrin-Based Controlled Release System in the Simulation of In Vitro Small Intestine

A novel cyclodextrin (CD)-based controlled release system was developed in the small intestine to control the rate of drug release, on the premise of enteric-coated tablets. The system was designed based on the enzymes exogenous β-cyclodextrin glycosyltransferase (β-CGTase) and endogenous maltase-glucoamylase (MG), wherein MG is secreted in the small intestine and substituted by a congenerous amyloglucosidase (AG). The vanillin-/curcumin-β-CD complexes were prepared and detected by Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC), and host CD degradation was measured based on the glucose yield. The combination of β-CGTase and AG was also functional in the CD complex system. The variations in the concentrations of added β-CGTase, with AG constantly in excess, could effectively alter the rate of host CD degradation and guest release by monitoring glucose production and color disappearance, thus, demonstrating that guest release in the CD complex system could be precisely controlled by changing the amount of β-CGTase used. Thus, the in vitro simulation of the system indicated that a novel controlled release system, based on endogenous MG, could be established in the small intestine. The CD-based controlled release system can be potentially applied in drug delivery and absorption in the small intestine.

Low-Molecular-Weight Gelators as Base Materials for Ointments

Ointments have been widely used as an efficient means of transdermal drug application for centuries. In order to create ointments suitable for various new medicinal drugs, the creation of ointment base materials, such as gels, has attracted much research attention in this decade. On the other hand, the chemical tuning of low-molecular-weight gelators (LMWGs) has been increasingly studied for two decades because LMWGs can be tailored for different purposes by molecular design and modification. In this review, several series of studies related to the creation of ointment base materials with enhanced properties using existing and newly-created LMWGs are summarized.

Multifunctional white-light-emitting metal-organic gels with a sensing ability of nitrobenzene

In this study, three novel luminescent nanofibrous metal-organic gels (MOGs) have been synthesized by the reaction of 1,3,5-tris(3-pyridylmethoxyl)benzene (L) with chloride salts of Cd(II), Hg(II), and Cu(II). The metal-ligand coordination, intermolecular π-π stacking and several other weak interactions found to play an important role in the formation of nanofibrous materials. The gel materials are characterized by rheology, diffuse reflectance spectra and various microscopic techniques such as TEM, FESEM, and AFM. The gels MOG-1 and MOG-2 were found to exhibit significant white photoluminescence, whereas the MOG-3 exhbits green emission upon excitation at 325 nm. Furthermore, the MOG-1 has shown its application as a chemosensor for the remarkable detection of nitroaromatics such as nitrobenzene (NB), 2,4-dinitrophenol (DNP). The significant quenching response for NB and DNP is attributed to the strong charge-transfer interactions between the electron-deficient aromatic ring of NB and the electron rich aromatic group of L in MOG-1. The crystal structure of Cd(II) complex of L reveals the formation one-dimensional network which contains strong π-π interactions within and between the networks and these strong π-π interactions generate the free charge carrier in all these nanofibrous gels.