Colorimetric and Fluorometric Discrimination of Geometrical Isomers (Maleic Acid vs Fumaric Acid) with Real-Time Detection of Maleic Acid in Solution and Food Additives

Heterobis imine Schiff base probe <b>L</b> is able to discriminate geometrical isomers (maleic acid vs fumaric acid) through sharp colorimetric as well as fluorogenic responses even conspicuous with the naked eye. Colorimetric as well as fluorogenic sensing of maleic acid among various carboxylic acids was also demonstrated in ethanol-buffer medium. Sensing behavior of <b>L</b> was corroborated by ¹H NMR spectra, mass spectrometry, and theoretical calculations. Subsequently sensing behavior of <b>L</b> was used to probe maleic acid in starch rich food samples

NIR- and FRET-Based Sensing of Cu²⁺ and S^2‑ in Physiological Conditions and in Live Cells

We have synthesized a new indole functionalized rhodamine derivative <b>L</b>_<b>1</b> which specifically binds to Cu²⁺ in the presence of large excess of other competing ions with visually observable changes in their electronic and fluorescence spectral behavior. These spectral changes are significant enough in the NIR and visible region of the spectrum and thus enable naked eye detection. The receptor, <b>L</b>_<b>1</b>, could be employed as a resonance energy transfer (RET) based sensor for detection of Cu²⁺ based on the process involving the donor indole and the acceptor Cu²⁺ bound xanthene fragment. Studies reveal that <b>L</b>_<b>1</b>–<b>Cu</b> complex is selectively and fully reversible in presence of sulfide anions. Further, fluorescence microscopic studies confirmed that the reagent <b>L</b>_<b>1</b> could also be used as an imaging probe for detection of uptake of these ions in HeLa cells

Ratiometric Fluorescent Probe Promotes Trans-differentiation of Human Mesenchymal Stem Cells to Neurons

Development of multifunctional theranostics is challenging and crucial for deciphering complex biological phenomena and subsequently treating critical disease. In particular, development of theranostics for traumatic brain injury (TBI) and understanding its repair mechanism are challenging and highly complex areas of research. Recently, there have been interesting pieces of research work demonstrated that a small molecule-based neuroregenerative approach using stem cells has potential for future therapeutic lead development for TBI. However, these works demonstrated the application of a mixture of multiple molecules as a “chemical cocktail”, which may have serious toxic effects in the differentiated cells. Therefore, development of a single-molecule-based potential differentiating agent for human mesenchymal stem cells (hMSCs) into functional neurons is vital for the upcoming neuro-regenerative therapeutics. This lead could be further extraploted for the design of theranostics for TBI. In this study, we have developed a multifunctional single-molecule-based fluorescent probe, which can image the transdifferentiated neurons as well as promote the differentiation process. We demonstrated a promising class of fluorescent probes (CP-4) that can be employed to convert hMSCs into neurons in the presence of fibroblast growth factor (FGF). This fluorescent probe was used in cellular imaging as its fluorescence intensity remained unaltered for up to 7 days of trans-differentiation. We envision that this imaging probe can have an important application in the study of neuropathological and neurodegenerative studies

Zn²⁺ and Pyrophosphate Sensing: Selective Detection in Physiological Conditions and Application in DNA-Based Estimation of Bacterial Cell Numbers

A diformyl-quinoline based receptor (<b>L</b>_<b>1</b>) exhibits selective colorimetric and fluorometric sensing of Zn²⁺ in aqueous medium at pH 7.4 based on the intraligand charge transfer (ICT) process. The <i>in situ</i> formed phenoxo-bridged complex, <b>L</b>_<b>1</b>·2Zn can selectively and specifically sense PPi among all the other biologically important anions including ATP through reversible binding. The detection limit for Zn²⁺ and PPi were found to be approximately 56 and 2 ppb, respectively. The unique selectivity of the PPi by the <b>L</b>_<b>1</b>-Zn ensemble could be used as an analytical tool to probe PPi generation in a prototype polymerase chain reaction (PCR) setup and track DNA amplification with higher sensitivity as compared to conventional agarose gel electrophoresis. Interestingly, the principle of PPi estimation in PCR rendered rapid estimation of bacterial cell numbers with a limit of detection of 10 CFU of <i>Escherichia coli</i> MTCC 433 in as early as 10 PCR cycles. The proposed method of PPi sensing offers interesting application potential in PCR-based rapid diagnostics for pathogenic agents and microbiological quality control

Mitochondria-Targeted New Blue Light-Emitting Fluorescent Molecular Probe

Discovery of a nontoxic fluorescent molecular probe to “light up” specific cellular organelles is extremely essential to understand dynamics of intracellular components. Here, we report a new nontoxic mitochondria-targeted linear bithiazole compound, containing trifluoroacetyl terminal groups, which emits intense blue fluorescence and stained mitochondria of various cells. Interestingly, the power of fluorescence is completely off when the bithiazole unit is stapled by a carbonyl bridge

Crystalline Domains Nested on Two-Dimensional Nanosheets as Heterogeneous Nanomachineries for the Sustainable Production of Bioactive Compounds from Chlorella sorokiniana

Naturally occurring bioactive compounds have attracted significant interest from the perspective of scientific and industrial aspects owing to the wide range of technological, economic, and healthcare benefits. Their synthetic origin still suffers from several impeding challenges, such as expensive extraction and low yield. To address these critical issues, a unique hybridized system termed “algal-nanohybrids” was established by integrating green microalgae, Chlorella sorokiniana, with carbon-based heterostructured nanomaterials (CHNs), enhancing the microalgal growth for the sustainable augmentation of bioactive compounds as renewable sources of secondary metabolites. Hitherto, this work presents a new avenue in the formation of CHNs comprising propene-bridged cyanurate tetramer crystals nested on two-dimensional (2D) nanosheets, possessing excellent photocatalytic activity along with biocompatibility for the sustainable production of bioactive compounds. Mechanistic insights into the formation of CHNs and their plausible interaction with the algal cells were deciphered using a suite of characterization techniques. The conceptual significance of CHNs was elaborated, as an efficient nanomachinery for bolstering the enhanced production of lutein (97%) from C. sorokiniana, which is higher than that reported for other lutein-producing microalgae grown under photoautotrophic conditions. Interestingly, CHNs not only promoted microalgal biomass by 88% but also enhanced the production of chlorophyll a and carotenoids by 42 and 75%, respectively. This unprecedented work advances the synthesis of biocompatible CHNs, which can provide a breakthrough in the industry for the production of natural lutein and other bioactive compounds from microalgae

Power of Tyrosine Assembly in Microtubule Stabilization and Neuroprotection Fueled by Phenol Appendages

Microtubules play a crucial role in maintenance of structure, function, axonal extensions, cargo transport, and polarity of neurons. During neurodegenerative diseases, microtubule structure and function get severely damaged due to destabilization of its major structural proteins. Therefore, design and development of molecules that stabilize these microtubule networks have always been an important strategy for development of potential neurotherapeutic candidates. Toward this venture, we designed and developed a tyrosine rich trisubstituted triazine molecule (TY3) that stabilizes microtubules through close interaction with the taxol binding site. Detailed structural investigations revealed that the phenolic protons are the key interacting partners of tubulin. Interestingly, we found that this molecule is noncytotoxic in PC12 derived neurons, stabilizes microtubules against nocodazole induced depolymerization, and increases expression of acetylated tubulin (Ac-K40), an important marker of tubulin stability. Further, results show that TY3 significantly induces neurite sprouting as compared to the untreated control as well as the two other analogues (TS3 and TF3). It also possesses anti-Aβ fibrillation properties as confirmed by ThT assay, which leads to its neuroprotective effect against amyloidogenic induced toxicity caused through nerve growth factor (NGF) deprivation in PC12 derived neurons. Remarkably, our results reveal that it reduces the expression of TrkA (pY490) associated with NGF deprived amyloidogenesis, which further proves that it is a potent amyloid β inhibitor. Moreover, it promoted the health of the rat primary cortical neurons through higher expression of key neuronal markers such as MAP2 and Tuj1. Finally, we observed that it has good serum stability and has the ability to cross the blood–brain barrier (BBB). Overall, our work indicates the importance of phenolic −OH in promoting neuroprotection and its importance could be implemented in the development of future neurotherapeutics