Evaluation of the Direct Interaction between Amino Acids and Glutathione-Coated CdTe Quantum Dots and Application in Urinalysis for Histidine Determination

Journal of the Brazilian Chemical Society

article

Barbosa, Leila S. V.¹  Teixeira, Leonardo S. G.¹  Korn, Maria G. A.¹  Santana, Rodolfo M. M.¹ 

[1] Departamento de Química Analítica, Instituto de Química, Universidade Federal da Bahia (UFBA), Campus Universitário de Ondina;Instituto Nacional de Ciência e Tecnologia (INCT em Energia e Ambiente), Instituto de Química, Universidade Federal da Bahia (UFBA), Campus Universitário de Ondina

关键词: amino acids;    histidine;    urine;    quantum dots;    clinical test;   

DOI  :  10.21577/0103-5053.20200212

学科分类：内科医学

来源: SciELO

【 摘 要 】

The present work aimed to direct amino acid (AA) sensing by quantum dots (QD) and development of an analytical method for potential fast clinical tests. Notably, AA with a positive charge or neutral polar chains, namely L-histidine (His) and L-threonine (Thr), responded to glutathione-coated CdTe (GSH-CdTe) (ΔF ≤ 90%, variation of fluorescence intensity). However, in ammoniacal buffer (0.25 mol L -1 ) at pH 8.0, 2.2 nm GSH-CdTe responded only to His. Static quenching with complex association constant (K sv ) varying from 2.81 to 0.94 (10 L mol -1 ) as well as van der Waals forces and/or hydrogen bonding were predicted for His-QD quenching mechanism and binding type. Additionally, thermodynamic parameters as ΔH = -76.5 kJ mol -1 (enthalpy), ΔS = -227.4 J K -1 mol -1 (entropy) and ΔG from -9.8 until -6.4 kJ mol -1 (Gibbs free energy) at 20 to 35 °C were estimated by van’t Hoff equation. Under optimal conditions, the developed method presented a linear range from 0.42 to 35 mmol L -1 (with correlation coefficient (r) of 0.9970, n = 7), good precision (relative standard deviations (RSD) < 2.5% for 2.5 and 20 mmol L -1 ; n = 6) and limit of detection 1.6 × 10 -4 mol L -1 (0.025 mg mL -1 ). Recovery tests were performed on artificial urine and human urine samples with recoveries ranging from 78.7 to 127.6%.

【 授权许可】

CC BY