RESUMO
The proposed L-histidine sensing system composed of a molecularly imprinted solid-phase microextraction component combined with a molecularly imprinted polymer sensor was used to determine critical levels of test analyte in a complex matrix of highly diluted human blood serum without any non-specific sorption and false-positive contributions. The molecularly imprinted polymer was a zwitterionic polymer brush derived from the disodium salt of EDTA and chloranil, grafted to solid-phase microextraction material. The hyphenated approach was able to detect L-histidine quantitatively with a limit of detection as low as 0.0435 ng/mL (RSD = 0.2%, S/N = 3).
Assuntos
Histidina/análise , Impressão Molecular/instrumentação , Impressão Molecular/métodos , Polímeros/química , Microextração em Fase Sólida/instrumentação , Microextração em Fase Sólida/métodos , Íons/química , Microscopia Eletrônica de Varredura , Estrutura Molecular , Sensibilidade e EspecificidadeRESUMO
Main inborn errors of metabolism diagnosable through uracil (Ura) analysis and the therapeutic monitoring of toxic 5-fluorouracil (5FU) in dihydro pyrimidine dehydrogenase (DPD) deficient patients require a sensitive, reproducible, selective and accurate method. In this work, an artificial receptor in the format of molecularly imprinted polymer (MIP) brush 'grafted to' the surface of sol-gel immobilized on cost-effective homemade solid-phase microextraction (SPME) fibers, individually imprinted with either of Ura and 5FU, was used in combination with a voltammetric sensor duly modified with the same MIP. This combination provided up to 10- and 8.4-fold preconcentrations of Ura and 5FU, respectively, which was more than sufficient for achieving stringent detection limits in the primitive diagnosis of uracil disorders and fluoropyrimidine toxicity in DPD-deficient patients. The proposed method permits the assessment of Ura and 5FU plasma concentrations with detection limits pf 0.0245 and 0.0484 ng mL(-1) (RSD = 1.0-2.5%, S/N = 3), respectively, without any problems of non-specific false-positives and cross-reactivities in complicated matrices of biological samples.
Assuntos
Fluoruracila/análise , Impressão Molecular/métodos , Microextração em Fase Sólida/métodos , Uracila/análise , Benzenossulfonatos/química , Sítios de Ligação , Deficiência da Di-Hidropirimidina Desidrogenase/diagnóstico , Fluoruracila/sangue , Fluoruracila/isolamento & purificação , Humanos , Microscopia Eletrônica de Varredura , Impressão Molecular/economia , Impressão Molecular/instrumentação , Polímeros/química , Sensibilidade e Especificidade , Microextração em Fase Sólida/economia , Microextração em Fase Sólida/instrumentação , Solventes/química , Espectroscopia de Infravermelho com Transformada de Fourier , Propriedades de Superfície , Uracila/sangue , Uracila/isolamento & purificaçãoRESUMO
Clinical manifestations owing to ascorbic acid deficiency demand an easy-to-use, rapid, robust and inexpensive technique, which can measure serum ascorbic acid at ultratrace level to attend the problem of hypovitaminosis C and acute cases of scurvy. In the present work, a novel molecularly imprinted polymer (MIP)-coated solid-phase microextraction (SPME) fiber that could be coupled to a complementary MIP-sensor was prepared with ascorbic acid as a template molecule. The characteristics and applications of this fiber were investigated. The same MIP receptor for both SPME and the corresponding sensor was able to enhance the preconcentration of analyte substantially so as to attain the stringent level of sensitivity in highly diluted aqueous, blood serum and pharmaceutical samples. The extraction yield of ascorbic acid (AA) with the MIP-coated fiber was found to be quantitative (detection limit 0.0396 ng mL(-1), RSD=2.3%, S/N=3) in aqueous samples without any problem of non-specific false positive results and cross-reactivity.
