Coumarin derivative-functionalized nanoporous silica as an on-off fluorescent sensor for detecting Fe3+ and Hg2+ ions: a circuit logic gate.

A highly efficient fluorescent sensor (S-DAC) was easily created by functionalizing the SBA-15 surface with N-(2-Aminoethyl)-3-Aminopropyltrimethoxysilane followed by the covalent attachment of 7-diethylamino 3-acetyl coumarin (DAC). This chemosensor (S-DAC) demonstrates selective and sensitive recognition of Fe3+ and Hg2+ in water-based solutions, with detection limits of 0.28 × 10-9 M and 0.2 × 10-9 M for Hg2+ and Fe3+, respectively. The sensor's fluorescence characteristics were examined in the presence of various metal ions, revealing a decrease in fluorescence intensity upon adding Fe3+ or Hg2+ ions at an emission wavelength of 400 nm. This sensor was also able to detect ferric and mercury ions in spinach and tuna fish. The quenching mechanism of S-DAC was investigated using UV-vis spectroscopy, which confirmed a static-type mechanism for fluorescence quenching. Moreovre, the decrease in fluorescence intensity caused by mercury and ferric ions can be reversed using trisodium citrate dihydrate and EDTA as masking agents, respectively. As a result, a circuit logic gate was designed using Hg2+, Fe3+, trisodium citrate dihydrate, and EDTA as inputs and the quenched fluorescence emission as the output.

A facile synthesis of chromeno[3,4-c]spiropyrrolidine indenoquinoxalines via 1,3-dipolar cycloadditions.

A one-pot, four-component reaction for the synthesis of novel chromeno[3,4-c]spiropyrrolidine-indenoquinoxalines is described via a 1,3-dipolar cycloaddition of 3-acetyl-coumarins with the azomethine ylides followed by deacetylation and protonation (deuteration). The products were obtained in moderate to high yields, and their structures were confirmed by 1H NMR, 13C NMR, FT-IR, and MS spectroscopy.

Long-Term Vaccine Delivery and Immunological Responses Using Biodegradable Polymer-Based Carriers.

Biodegradable polymers are largely employed in the biomedical field, ranging from tissue regeneration to drug/vaccine delivery. The biodegradable polymers are highly biocompatible and possess negligible toxicity. In addition, biomaterial-based vaccines possess adjuvant properties, thereby enhancing immune responses. This Review introduces the use of different biodegradable polymers and their degradation mechanism. Different kinds of vaccines, as well as the interaction between the carriers with the immune system, then are highlighted. Natural and synthetic biodegradable micro-/nanoplatforms, hydrogels, and scaffolds for local or targeted and controlled vaccine release are subsequently discussed.

Dual Photo- and pH-Responsive Spirooxazine-Functionalized Dextran Nanoparticles.

A dual photo- and pH-responsive spirooxazine-functionalized polymer was synthesized by functionalization of dextran with a spirooxazine derivative (SO-COOH). The functionalized dextran derivatives can form nanoparticles in aqueous medium. Under UV light irradiation, the spirooxazine-functionalized dextran (Dex-SO) nanoparticles isomerize to zwitterionic merocyanine-functionalized dextran (Dex-MC), which leads to aggregation. However, the process is reversible upon irradiation with visible light. Under acidic conditions, the hydrophobic spirooxazine is protonated, and the nanoparticles aggregate or swell at pH values of 5 or 3, respectively. The encapsulation of the hydrophobic fluorescent dye Nile Red as model drug allowed us to gain more information about the structural changes under stimulation of UV light and acid treatment.

Preparation and characterization of rod-like chitosan-quinoline nanoparticles as pH-responsive nanocarriers for quercetin delivery.

Novel chitosan-quinoline nanoparticles as anticancer drug nanocarriers were prepared using 2-chloro-3-formylquinoline and 3-formylquinolin-2(1H)-one as non-toxic modifying agents via oil-in-water nanoemulsion technique. Chitosan-quinoline nanoparticles were characterized by FT-IR, UV-vis spectrophotometry, XRD, SEM, AFM and DLS techniques. The morphological and particle size studies demonstrated that drug-loaded chitosan-quinoline nanoparticles have a regular nanorod shape and monolithic structure with the desired particle size of 141 to 174.8 nm and a negative zeta potential of -2.4 to -14.1 mV. Drug loading capacity (LC) and encapsulation efficiency (EE) were achieved using quercetin as a hydrophobic anticancer drug and were about 4.8-9.6% and 65.8-77%, respectively. The in vitro release studies displayed great pH-sensitive release behavior. Evaluation of the anticancer efficacy of quercetin loaded chitosan-quinoline nanoparticles using the in vitro cytotoxicity studies against HeLa cells indicated that the chitosan nanoparticles are a promising candidate for the anticancer drugs delivery.

Development of photo and pH dual crosslinked coumarin-containing chitosan nanoparticles for controlled drug release.

A new strategy has been developed to the fabrication of chitosan nanoparticles as anticancer drug nanocarriers with ultraviolet-responsive coumarin derivatives and pH-responsive imine groups. For this purpose 8-formyl-7-hydroxy-4-methylcoumarin (8-FHMC) was initially synthesized as novel and dual crosslinking agent in order to produce coumarin-containing chitosan nanoparticles via oil-in-water nanoemulsion system. The structure of the resultant compounds and nanoparticles were confirmed by means of 1H NMR, FT-IR, UV-vis spectroscopy and XRD. The morphology and size distribution of the coumarin-containing chitosan nanoparticles was also characterized using SEM, AFM and DLS. The drug-loaded coumarin-containing chitosan nanoparticles were stable at physiological conditions, and can also be disassociated by the cleavage of imine linkages in the crosslinking segments under acidic condition. Compared to non-photo-crosslinked chitosan nanoparticles, photo-crosslinked chitosan nanoparticles displayed controllable and slower release. Thus, we have showed that chitosan nanoparticles crosslinked by coumarin with photo- and pH-responsive properties is a promising and novel drug carrier for designing intelligent drug delivery systems.