Study On The Application Of Carbon Dots In Pharmaceutical Analysis And Regulation Of Luminescent Properties

Carbon dots are a new type of graphene-based nanomaterials with fluorescent properties.Due to its good physical optical properties and broad application prospects,it has attracted the attention of considerable researchers.Compared with conventional fluorescent probes?for example,organic molecules,metal nanoclusters and semiconductor quantum dots?,carbon dots have good light stability,inherent hydrophilicity,unique biocompatibility,rich carbon sources,easy synthesis and surface modification.It has been widely used in ion and molecular detection,light-emitting devices,selective imaging,anti-counterfeiting and other fields.In this paper,a series of fluorescent carbon dots were mainly prepared by microwave and hydrothermal methods.The effects of reactants on the performance of carbon dots and the use of carbon dots as probes for the detection of chlorpromazine hydrochloride in urine and ascorbic acid in serum were studied.1.Redox modulated fluorometric sensing of ascorbic acid by using a hybrid material composed of carbon dots and CoOOH nanosheetsAscorbic acid?AA?is a crucial biological molecule in the human body.Inadequate AA in the body can induce a disease called scurvy,while supplementation with excess AA may give rise to urinary stones,diarrhea and stomach convulsion.Consequently,the development of a sensitive approach for accurately and efficiently monitoring of AA in biological samples fields is of paramount importance for medical diagnosis.Carbon dots?CDs?were hydrothermally prepared from gelatin as the sole precursor,which were hybridized with NSs to form the fluorescence probe CD-CoOOH.It was found that NSs can evidently quench the luminescence of CDs via IFE.Upon addition of AA,the fluorescent quenching ability of NSs is extremely disturbed and NSs will be reduced to Co²⁺,thereby causing the blue fluorescence of CDs to recover.Our approach,as a burgeoning strategy,may open up a new path for more sensitive and quicker testing of AA.The hybrid nanoprobe has a linear response in the 0.8?12.5?mol L^-?16?and12.5?690.0?mol L^-?16?AA concentration ranges and a 0.025?mol L^-?16?limit of detection.The CD-CoOOH as a fluorescent probe is employed for the analysis of AA in human serum samples.The recovery rate of AA in human serum samples is range from 96.8%to 100.5%.This strategy is also designed to fabricate an“AND”logic gate,eliminating sophisticated material decoration and chemical tracking.2.Cost effective and facile fluorescent probes for label-free recognition of chlorpromazine hydrochloride and logic gate operationChlorpromazine hydrochloride?CPH?,is a phenothiazine drug containing an aliphatic side chain,which is beneficial for treating psychiatric patients suffering from depression.It has the effects of controlling excitement,hyperkinetic symptoms,anxiety and other psychomotor disorders of persons with schizophrenia and reducing the manic phase of manic depressive states.CPH is also applied to prevent vomiting and intravenous anti-hypertensive therapeutics.However,if the concentration of CPH exceeds a certain value,there is a risk of poisoning.In order to ensure the quality of the drug and prevent drug poisoning,it is necessary to accurately measure the content of CPH.Therefore,it is necessary to establish a new method for detecting the concentration of CPH.In this section,water-soluble nitrogen-doped carbon dots?N-CDs?possessing strong blue fluorescence were synthesized by one-step hydrothermal treatment using citric acid and semicarbazide hydrochloride with NaOH as solvent.The maximum excitation and emission wavelengths of N-CDs are located at 340 and 427 nm,respectively,and its fluorescence quantum yield was found to be 8.96%.The N-CDs interacted with CPH,leading to the quenching of strong fluorescence.In this system,two linear ranges of 7.5?100.0?mol L^-?16?and 100.0?1000.0?mol L^-?16?CPH could be easily tracked,and a 0.043?mol L^-?16?detection limit was available.Based on the above phenomenon,a“switch-off”fluorescent probe with excellent sensitivity and superior selectivity was designed for specifically detecting CPH,and an“AND”logic gate for sensing CPH was first proposed.The as-constructed sensor was conditioned for CPH determination in spiked human urine.The recoveries of the known spiked amounts of CPH in urine are 96.12%?100.1%with RSD around 1.26%?3.02%.3.Insight into the effect of raw materials on visible fluorescence emissions of carbon dotsWe presented a stratety for exploring the effects of the reactants on the characteristics of the nitrogen-doped carbon dots.Nitrogen doped carbon dots?N-CDs?were formed by microwave approach using citric acid monohydrate?CA?as carbon source and semicarbazide?SE?,urea?UA?and formamide?FA?as nitrogen source with NaOH,H2O and HCl as solvent,respectively.The nine carbon dots were prepared by microwave method.It was found that when the same carbon source reacts with different nitrogen sources,the higher the nitrogen content of the carbon dots obtained in the same solvent,the higher the fluorescence quantum yield and the blue shift of the fluorescence emission peak,which is due to the relatively strong N atom electronic affinity.At the same time,when the carbon source and nitrogen source are the same,the solvent changed from NaOH to H₂O,leading to the following two phenomena:the emission peaks have been red-shifted respectively and the fluorescence quantum yield of carbon dots synthesized under alkaline conditions is lower than that synthesized under neutral conditions,indicating that the solvent has an effect on peak position and fluorescence quantum yield.It shows that the synthesis of carbon dots by controlling the precursors and reaction conditions can not only regulate the functional groups on the surface of the carbon dots,but also change the charge characteristics of the carbon dots,thereby achieving specific recognition of the target substance.