A novel interfacial route has been developed for the synthesis of a bright-red-emitting new subnanocluster, Au(23), by the core etching of a widely explored and more stable cluster, Au(25)SG(18) (in which SG is glutathione thiolate). A slight modification of this procedure results in the formation of two other known subnanoclusters, Au(22) and Au(33). Whereas Au(22) and Au(23) are water soluble and brightly fluorescent with quantum yields of 2.5 and 1.3 %, respectively, Au(33) is organic soluble and less fluorescent, with a quantum yield of 0.1 %. Au(23) exhibits quenching of fluorescence selectively in the presence of Cu(2+) ions and it can therefore be used as a metal-ion sensor. Aqueous- to organic-phase transfer of Au(23) has been carried out with fluorescence enhancement. Solvent dependency on the fluorescence of Au(23) before and after phase transfer has been studied extensively and the quantum yield of the cluster varies with the solvent used. The temperature response of Au(23) emission has been demonstrated. The inherent fluorescence of Au(23) was used for imaging human hepatoma cells by employing the avidin-biotin interaction.
Gasotransmitters belong to the subfamily
of endogenous gaseous
signaling molecules, which find a wide range of biomedical applications.
Among the various gasotransmitters, nitric oxide (NO) has an enormous
effect on the cardiovascular system. Apart from this, NO showed a
pivotal role in neurological, respiratory, and immunological systems.
Moreover, the paradoxical concentration-dependent activities make
this gaseous signaling molecule more interesting. The gaseous NO has
negligible stability in physiological conditions (37 °C, pH 7.4),
which restricts their potential therapeutic applications. To overcome
this issue, various NO delivering carriers were reported so far. Unfortunately,
most of these NO donors have low stability, short half-life, or low
NO payload. Herein, we review the synthesis of NO delivering motifs,
development of macromolecular NO donors, their advantages/disadvantages,
and biological applications. Various NO detection analytical techniques
are discussed briefly, and finally, a viewpoint about the design of
polymeric NO donors with improved physicochemical characteristics
is predicted.
Alternating sequencing of styrene‐maleimide/maleic anhydride (S‐MI/MA) in the copolymer chain is known for a long time. But since early 2000, this class of copolymers has been extensively studied using various living/controlled polymerization techniques to design S‐MI/MA alternating copolymers with tunable molecular weight, narrow dispersity (Ð), and precise chain‐end functionality. The widespread diverse applications of this polymeric backbone are due to its ease of synthesis, cheap starting materials, high precision in alternating sequencing, and facile post‐polymerization functionalization with simple organic reactions. Recently, S‐MI/MA alternating copolymers have been rediscovered as novel polymers with unprecedented emissive behavior. It outperforms the traditional fluorophores with no aggregation caused quenching (ACQ), aqueous solubility, and greater cell viability. Herein, the origin of alternating sequence, synthesis, and recent (2010‐Present) developments in applications of these polymers in different fields are elaborately discussed, including the advantages of the unconventional luminogenic property. This review article also highlights the future research directions of the versatile S‐MI/MA copolymers.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.