Enantioselective Voltammetric Sensors Based on Amino Acid Complexes of Cu(II), Co(III), and Zn(II)

Abstract

The electrochemical and analytical characteristics of enantioselective sensors based on glassy carbon electrodes modified by chelate complexes (bis(L-phenylalaninate) copper(II), glycinato-L-phenylalaninate copper(II), tris(L-phenylalaninate) cobalt(II), bis(L-phenylalaninate) zinc) are studied. It is found that the most promising sensor for determining tryptophan enantiomers is the sensor modified by copper(II) (bis)L-phenylalaninate. In determining tryptophan enantiomers, this sensor provides a linear concentration range from 6.25 × 10 -7 to 0.5 × 10 -3 M for L-tryptophan and from 5 × 10 -6 to 0.5 × 10 -3 M for D-tryptophan. The sensor is more sensitive to L-tryptophan. The proposed sensor was used for the recognition and determination of tryptophan enantiomers in human urine and plasma samples, and also in a mixture of enantiomers. The statistical assessment of the results of determinations by the spiked-found method indicates the absence of a significant systematic error.

Chiral voltammetric sensor on the basis of nanosized MFI zeolite for recognition and determination of tryptophan enantiomers

“…It is seen from the table that this sensor has a wide linear concentration range and a lower Trp detection limit compared to the other enantioselective sensors [44–45, 47–57]. In terms of the enantioselectivity coefficient, this sensor is comparable or superior to some others [44–46, 48, 51, 53–57] reported in the literature. In addition, this method of creating a chiral sensor is simple and relatively inexpensive.…”

“…In addition, this method of creating a chiral sensor is simple and relatively inexpensive. At the same time, the developed sensor is stable for 30 days, while the stability of the others reported in the literature [44][45][46][47][48][49][50][51][52][53][54][55][56][57] is maintained only for up to a maximum of 7 days.…”

Rational design of highly enantioselective composite voltammetric sensors using a computationally predicted chiral modifier

“…[14][15][16][17][18][19] It is well known that a chiral modifier is the key component for building an electrode's chiral surface for creating high enantioselectivity (ϑ) for selected analytes. 19 The majority of methods (except for molecular imprinting [20][21][22][23][24][25][26] ) use one or more chiral components [27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44] as modifiers for building a chiral layer on the electrode surface (Scheme 1). Obviously, the value of enantioselectivity depends on the structure of the modifier, and for any chiral analyte, the corresponding "complementary" modifier exists that provides the best enantioselectivity (Scheme 2).…”

“…However, at present, there are no simple and fast methods for determining a "complementary" chiral modifier for a specified analyte, and, as a result, there is no technology for a rapid design of highly enantioselective composite voltammetric sensors. In most cases, the choice of a chiral modifier is based on a brute-force search 27 or on a similarity to previously reported modifiers. 28,29 Certainly, these approaches do not promise that the best modifier for a given analyte will be identified in a reasonable time period.…”

“…The majority of methods (except for molecular imprinting 20–26 ) use one or more chiral components 27–44 as modifiers for building a chiral layer on the electrode surface (Scheme 1). Obviously, the value of enantioselectivity depends on the structure of the modifier, and for any chiral analyte, the corresponding “complementary” modifier exists that provides the best enantioselectivity (Scheme 2).…”