Wenqian Yang

A glucose-selective fluorescence sensor based on boronicacid-diol recognition

A glucose selective diphenylboronic acid fluorescent sensor (10a) with a K(a) of 1472M(-1) has been synthesized and evaluated. This sensor shows a 43- and 49-fold selectivity for glucose over fructose and galactose, respectively. The binding affinity improvement is about 300-fold and the selectivity improvement for glucose over fructose is about 1400-fold compared with the monoboronic acid compound, phenylboronic acid. 1H NMR studies indicate that sensor 10a binds with alpha-D-glucofuranose in a bidentate manner (1:1 ratio).

Diboronic acids as fluorescent probes for cells expressing sialyl lewis X

A series of fluorescent diboronic acids was synthesized in nine steps as potential sensors for sialyl Lewis X (sLex). The fluorescent binding studies of these sensors with sLex were carried out in a mixed aqueous solution. Compound 7e was found to show the strongest fluorescence enhancement upon binding with sLex. Using cell cultures, 7e was shown to label sLex-expressing HEPG2 cells at 1 microM, while non-sLex-expressing cells were not labeled.

A novel type of fluorescent boronic acid that shows large fluorescence intensity changes upon binding with a carbohydrate in aqueous solution at physiological pH

In this paper we report 8-quinolineboronic acid as a novel type of fluorescent probe for carbohydrates. This boronic acid responds to the binding of a carbohydrate with over 40-fold increases in fluorescence intensity and shows optimal fluorescence change at physiological pH in aqueous solution.

Catechol pendant polystyrene for solid-phase synthesis

A catechol pendant polystyrene polymer was prepared from the Merrifield resin via a convenient procedure with high-density loading. Due to the high affinity binding between catechol and boronic acid, the polymer resin readily captures boronic acid compounds. The feasibility of using immobilized catechol to capture boronic acid products for purification and solid-phase transformation was demonstrated. Moreover, the immobilized catechol was also used for the preparation of resin-bound catecholborane, which can be used as a solid-phase amidation reagent.

A new class of fluorescent boronic acids that have extraordinarily high affinities for diols in aqueous solution at physiological pH.

The boronic acid group is an important recognition moiety for sensor design. Herein, we report a series of isoquinolinylboronic acids that have extraordinarily high affinities for diol-containing compounds at physiological pH. In addition, 5- and 8-isoquinolinylboronic acids also showed fairly high binding affinities towards D-glucose (K(a)=42 and 46 M(-1), respectively). For the first time, weak but encouraging binding of cis-cyclohexanediol was found for these boronic acids. Such binding was coupled with significant fluorescence changes. Furthermore, 4- and 6-isoquinolinylboronic acids also showed the ability to complex methyl α-D-glucopyranose (K(a)=3 and 2 M(-1), respectively).

The first fluorescent sensor for D-glucarate based on the cooperative action of boronic acid and guanidinium groups

A new fluorescent sensor (1) with a recognition unit consisting of a boronic acid moiety and a guanidinium unit shows selective binding of D-glucarate in aqueous solution.

Synthesis and evaluation of dual wavelength fluorescent benzo[b]thiophene boronic acid derivatives for sugar sensing.

Cell surface glycoproteins have been known to play very important roles in various physiologic and pathologic processes. Small molecule compounds capable of carbohydrate recognition can be very useful for the development of sensing, diagnostic, and therapeutic agents. Along this line, we are interested in developing water‐soluble fluorescent boronic acid compounds for carbohydrate recognition. As such, a series of benzo[b]thiophene boronic acid derivatives have been synthesized and their fluorescent properties analyzed at physiologic pH. Benzo[b]thiophene derivatives were found to be a new type of fluorescent reporter compounds capable of dual fluorescent emission under physiologic pH conditions. Compounds 1, 3, 4, 5, and 6 showed unusual emission wavelength shifts upon binding of sugars. These boronic acids will be useful tools for building glycoprotein biosensors for biologic applications.

Selective elimination of perennial ryegrass by activation of a pro-herbicide through engineering E. coli argE gene

Perennial ryegrass is widely used for overseeding dormant bermudagrass on golf courses and sports fields in Southeastern United States to provide green color and improved playability. Late spring and summer persistence of perennial ryegrass may decrease the quality of the bermudagrass turf and reduce its winter hardiness. To help solve this problem, we developed a strategy to activate a pro-herbicide within the transgenic perennial ryegrass plants and to cause self elimination of the plants. An E. coli argE gene was introduced into perennial ryegrass by the biolistic method, which resulted in four independently transformed green plants. The mRNA of argE gene was detected in three of the plants by RT-PCR. Perennial ryegrass plants expressing the argE transgene were selectively controlled upon application of a pro-herbicide, N-acetyl-l-phosphinothricin (or N-acetyl-PPT), since the N-acetylornithinase encoded by argE gene is able to convert N-acetyl-PPT to the herbicide phosphinothricin (PPT). The non-transgenic bermudagrass plants were unaffected by the treatment. This approach provides a means to selectively remove a group of transgenic plants without affecting other plants growing with them.

A fluorescent bisboronic acid compound that selectively labels cells expressing oligosaccharide Lewis X.

Two fluorescent diboronic acid compounds (6a and 6b) with a dipeptide linker were synthesized as potential sensors for cell surface saccharide Lewis X (Le(X)). Compound 6a with a dipeptide (H-Asp-Ala-) as the linker was found to selectively label CHOFUT4 cells, which express Le(x), at micromolar concentrations, while non-Le(x)-expressing control cells were not labeled.