Synthesis and characterization of citrate-based fluorescent small molecules and biodegradable polymers

Abstract

Novel citric acid based photoluminescent dyes and degradable polymers are synthesized via a facile “one-pot” reaction. A comprehensive understanding of the fluorescence mechanisms of the resulting citric acid-based fluorophores is reported. Two distinct types of fluorophores are identified: a thiozolopyridine family with high quantum yield, long lifetime, and exceptional photostability, and a dioxopyridine family with relatively lower quantum yield, multiple lifetimes, and solvent-dependent band shifting behavior. Applications in molecule labeling and cell imaging were demonstrated. The above discoveries contribute to the field of fluorescence chemistry and have laid a solid foundation for further development of new fluorophores and materials that show promise in a diversity of fluorescence-based applications.

Citrate‐Based Fluorescent Biomaterials

“…For example, researchers revealed the reaction possibility of citrate-based molecular fluorophores by reacting TPA (CA-Cys) and DPR (CA-Ala) structured fluorophores with 1,8-octanediol. [32, 34] LC-ESI-MS mass spectrum confirmed the ester bonds between fluorophores and diols. Fluorescence studies also showed that the resulting BPLP-TPA had identical fluorescence properties as that of CA-Cys and BPLP-Cys, including an excitation-independent emission.…”

“…Yang’s group also prepared a series of CA based fluorophores via heating CA with various primary amines, amino acids, or analogs of amino acids. [32] After analyses of chemical structures and fluorescence properties, fluorescence mechanism based on TPA and DPR structures were established, depending on the choices of amines. As such, the authors proposed several amine reagents which can readily be used to prepare efficient CA based fluorescent molecules.…”

“…[32] The molecular/cellular labeling were achieved through conjugation between free carboxyl groups of molecular fluorophores and the surface of BSA/fibroblasts using carbodiimide chemistry. Strong blue fluorescence emission were observed from BSA molecules conjugated with CA-Cys, which indicated the molecular labeling capability of CA-Cys fluorophores.…”

“…[29–33] Recently, due to the importance of small molecular fluorophores formed by CA and amine based molecules, various citrate-based fluorescent molecules have also been developed. [32, 34–36] …”

Citrate chemistry and biology for biomaterials design

“…The 6-membered ring structure formed by citric acid and α-amino acids has been identified to be the fluorescent moiety in BPLP. These fluorescent moieties can also be released from BPLP during degradation, as CA-Cys has been found in the alkaline hydrolysis productions of BPLP-Cys [39]. Meanwhile, a family of citratebased fluorescent small molecules have been synthesized via a one-pot reaction of citric acid with a primary amine or amino acid.…”