Temporal Release of Cell Cycle Regulator α-Lipoic Acid: An NIR-Light (Two-Photon) Activatable Quinoxaline-Based Nano-Prodrug Delivery System.

The regulation of the cell cycle has recently opened up a new research perspective for cancer treatment. So far, no effort has been made for temporal control of cell cycles using a photocleavable linker. Presented herein is the first report of regulation of disrupted cell cycles through the temporal release of a well-known cell cycle regulator α-lipoic acid (ALA), enabled by a newly designed NIR-active quinoxaline-based photoremovable protecting group (PRPG). The suitable quinoxaline-based photocage of ALA (tetraphenylethelene conjugated) has been formulated as fluorescent organic nanoparticles (FONs) and used effectively as a nano-DDS (drug delivery system) for better solubility and cellular internalization. Fascinatingly, the enhanced TP (two-photon) absorption cross section of the nano-DDS (503 GM) signifies its utility for biological applications. Using green light, we have successfully controlled the time span of cell cycles and cell growth of skin melanoma cell lines (B16F10) by the temporal release of ALA. Further, in silico studies and PDH activity assay supported the observed regulatory behavior of our nano-DDS with respect to photoirradiation. Overall, this approach expands the research path toward a futuristic photocontrolled toolbox for cell cycle regulation.

Spatiotemporal photo-release of hydrogen sulphide from ß-carboline-derived nanoparticles for therapeutic applications.

Hydrogen sulfide (H2S) is an important gasotransmitter that plays a significant role in the regulation of various physiological activities. The therapeutic effect of H2S is highly concentration-dependent and has recently been recognized for wound healing applications. Until now, the reported H2S delivery systems for wound healing applications have been focused on polymer-coated cargo systems for the encapsulation of H2S donors that are based just on endogenous stimuli-responsive systems such as pH or glutathione. These delivery systems lack spatio-temporal control and can cause premature H2S release depending on the wound microenvironment. In this regard, polymer-coated light-activated gasotransmitter donors provide a promising and efficient means of delivering high spatial and temporal control along with localized delivery. Hence, for the first time, we developed a ß-carboline photocage-based H2S donor (BCS) and formulated it into two photo-controlled H2S delivery systems: (i) Pluronic-coated nanoparticles loaded with BCS (Plu@BCS nano); and (ii) a hydrogel platform impregnated with BCS (Plu@BCS hydrogel). We investigated the mechanism of photo-release and the photo-regulated H2S release profile from the BCS photocage. We found that the Plu@BCS nano and Plu@BCS hydrogel systems were stable and did not release H2S without light treatment. Interestingly, external light manipulation, such as changing the irradiation wavelength, time, and location, regulate the release of H2S precisely. Biological studies (in vitro) suggest that the Pluronic coating on the BCS photocage makes the donor highly biocompatible and desirable for biological applications.

Processing of semolina, a wonder resource for resistant starch production: In vitro digestibility and biochemical evaluation.

With the advent of modern technology, the utilization of residues obtained after food processing are being largely explored for commercialization. Semolina, a starch rich food ingredient is one of such byproducts of food processing that has not been yet vividly studied, although it is profusely used as an important ingredient in Indian cuisines. Rapid digestibility of most starch rich foods boosts up the blood glucose level. Thus, the present study put forward an attempt to curtail the rapid digestibility of starch rich semolina flour by increasing its resistant starch content through enzymatic process. The enzymatically modified semolina flour (MS) was compared with its native counterpart (NS) on grounds of their digestibility pattern, biochemical and functional properties. A rise in resistant starch content by 9.3 ± 1.6 %, amylose content by 10.9 ± 1.2 %, crystallinity by 10.4 % and the drop in readily digestible starch by 11.9 ± 1.4 % and oil absorption by 2.1 ± 0.3 g/g were observed in MS. These initial findings of the present study are interesting as the results showed elevated potential of the modified semolina flour to be used as functional ingredient in cuisines worldwide.

Single component photoresponsive fluorescent organic nanoparticles: a smart platform for improved biomedical and agrochemical applications.

In the last two decades, light responsive nano drug delivery systems (DDSs) have gained considerable importance, particularly in the area of biology and medicine. In general, light responsive nano DDSs are bicomponent and constructed using two ingredients, namely a nanocarrier and a phototrigger. The synthesis of these bicomponent nano DDSs requires multiple steps, which limits their applications. Hence, we have reported single component light responsive nano DDSs using fluorescent organic nanoparticles (FONPs) which acted both as a nanocarrier and a phototrigger. This feature article provides an overview of recently developed light responsive single component FONPs and their applications in the regulated release of anticancer drugs, gasotransmitters, antibacterial agents, and pesticides, and also as efficient PDT agents. We have summarised the synthesis, characterisation, and photophysical, photochemical, and in vitro behaviours of these light responsive FONPs. In addition, we also discussed the advantages of using FONPs as a nano DDS for cellular studies like: excellent biocompatibility, efficient cellular internalisation, real time monitoring of the drug release ability inside the cells, and enhanced cytotoxicity due to regulated release of bioactive molecules inside the cells.

Recent Advances on Stimuli-Responsive Combination Therapy against Multidrug-Resistant Bacteria and Biofilm.

The widespread occurrence of infections from multidrug-resistant (MDR) bacteria is a global health problem. It has been amplified over the past few years due to the increase in adaptive traits in bacteria and lack of advanced treatment strategies. Because of the low bioavailability and limited penetration at infected sites, the existing antibiotics often fail to resist bacterial growth. Recently, developed stimuli-responsive drug delivery systems and combinatorial therapeutic systems based on nanoparticles, metal-organic frameworks, hydrogels, and organic chromophores offer the ability to improve the therapeutic efficacy of antibiotics by reducing drug resistance and other side effects. These therapeutic systems have been designed with the relevant chemical and physical properties that respond to specific triggers resulting in spatiotemporal controlled release and site-specific transportability. This review highlights the latest development of single and dual/multistimuli-responsive antibiotic delivery systems for combination therapies to treat MDR bacterial infections and biofilm eradication.

A Natural Alkaloid, ß-Carboline, as a One- and Two-Photon Responsive Fluorescent Photoremovable Protecting Group: Sequential Release of the Same or Different Carboxylic Acids.

The ß-carboline moiety, substituted at the C1 and C3 benzylic positions with a leaving group, has been demonstrated for the first time as a photoremovable protecting group for time-dependent sequential release of two (same or different) carboxylic acids upon one- and two-photon light irradiation. Density functional theory calculations suggest that the electronic environment of the ß-carboline moiety at C1 and C3 positions plays a key role in the rate of photorelease.