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Fluorescent carbon dots (CDs) have attracted considerable interest due to their superior optical properties and facile preparation. In this work, O-phenylenediamine and melamine were used as precursors for the one-step hydrothermal synthesis of novel orange emissive CDs (O-CDs) in an aqueous solution. The fluorescence intensity (580 nm) of the O-CDs exhibited a good linear relationship with Ag+ in the range of 0.0–50.0 μM with the detection limit of 0.289 μM. Moreover, the O-CDs were successfully used to determine Ag+ in biological samples (Hela cells) because of their low cytotoxicity, and good biocompatibility. Besides, the O-CDs-doped solid-phase detection materials (test paper and hydrogel) were employed to monitor Ag+ qualitatively and quantitatively, indicated that the O-CDs had a great capacity for the detection of Ag+ in biological and environmental areas. Based on their extraordinary fluorescence property, the O-CDs could also be used as security ink. Overall, based on their excellent fluorescent performance, the CDs in this study have significant potential for practical application toward solid-phase sensing and security ink.

Multicolor carbon dots (CDs) possess tremendous potential applications, especially in optoelectronic devices. However, further applications of multi-color LED have been constrained due to the very limited researches concerning the wavelength control mechanism of multi-color CDs. In this work, through theoretical calculation and experimental veri cation, the regulatory effects of sp 2 conjugated domain on the uorescence wavelength of CDs were explored. Firstly, through a regulation on the structure size and the introduction of amide bonds, four kinds of structures were designed in DFT theoretical calculation to explore the in uence of sp 2 conjugated domain on the uorescence wavelength of CDs theoretically. Then, using thiourea and p-phenylenediamine as the precursors and by regulating the reaction solvents, multicolor CDs with blue, green and red uorescence emission were prepared to experimentally verify the emission mechanism. It was con rmed that the increasing structure size and the introduction of amide bond would induce an increasing size of the sp 2 conjugated domain, leading to the red shift of the CDs uorescence wavelength. Finally, in order to suppress the self-quenching performance, the CDs@PVP uorescent lm possessing bright solid-state uorescence was constructed for a better application in light-emitting diodes. The approach provided an effective strategy to realize the programmed regulation on the uorescence wavelength of CDs, offering us full of potentials for the applications of CDs in the photoelectric device elds.

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Glaucoma is the leading cause of irreversible blindness, and its treatment is attracting widespread attention. Drug-loaded lacrimal suppositories can effectively treat xerophthalmia, but there is little research on the treatment of glaucoma with drug-loaded lacrimal suppositories. This article explored and expanded the non-pharmacological model of lacrimal suppository therapy for glaucoma by using a combination of lacrimal suppository and medication. The drug-loaded lacrimal suppository was rationally designed through the conjugation of gelatin with polyamide (PAM) via the formation of amide linkages, followed by Schiff base reaction grafting with latanoprost. In vitro drug release studies showed that latanoprost released from drug-loaded lacrimal embolus had sustained-release properties with a release time of 33 days and a drug release volume of 82.6%. The biological evaluation of drug-loaded lacrimal thrombus was carried out by IOP test, retinal potential test, and retinal H&E staining. The results showed that the IOP decreased to 27.125 ± 1.1254 mmHg, and the a and b waves of retinal potential increased to 4.39 ± 0.16 μV and 67.9 ± 2.17 μV, respectively. It indicated that latanoprost lacrimal suppository has a good therapeutic effect on glaucoma.