Stereochemical identification of glucans by a donor–acceptor–donor conjugated pentamer enables multi-carbohydrate anatomical mapping in plant tissues

Abstract

Optotracing is a novel method for analytical imaging of carbohydrates in plant and microbial tissues. This optical method applies structure-responsive oligothiophenes as molecular fluorophores emitting unique optical signatures when bound to polysaccharides. Herein, we apply Carbotrace TM 680, a short length anionic oligothiophene with a central heterocyclic benzodithiazole (BTD) motif, to probe for different glucans. The donor-acceptor-donor type electronic structure of Carbotrace TM 680 provides improved spectral properties compared to oligothiophenes due to the possibility of intramolecular chargetransfer transition to the BTD motif. This enables differentiation of glucans based on the glycosidic linkage stereochemistry. Thus a-configured starch is readily differentiated from b-configured cellulose. The versatility of optotracing is demonstrated by dynamic monitoring of thermo-induced starch remodelling, shown in parallel by spectrophotometry and microscopy of starch granules. Imaging of Carbotrace TM 680 bound to multiple glucans in plant tissues provided direct identification of their physical locations, revealing the spatial relationship between structural (cellulose) and storage (starch) glucans at sub-cellular scale. Our work forms the basis for the development of superior optotracers for sensitive detection of polysaccharides. Our non-destructive method for anatomical mapping of glucans in biomass will serve as an enabling technology for developments towards efficient use of plant-derived materials and biomass.

Optotracing for selective fluorescence-based detection, visualization and quantification of live S. aureus in real-time

“…Optotracing also enabled the development of a diagnostic assay for biofilm-related urinary tract infections by detection of native cellulose produced by uropathogenic E. coli (UPEC) in urine from infected patients 15 . We expanded optotracing to become a versatile method for nondisruptive analysis of polysaccharides 16 . The donor-acceptor-donor (D-A-D)-type electronic structure of the optotracers' conjugated backbone increased the spectral separation of bound optotracers.…”

“…The donor-acceptor-donor (D-A-D)-type electronic structure of the optotracers' conjugated backbone increased the spectral separation of bound optotracers. A remarkable sensitivity to the glucan stereochemistry was observed, with β-configured cellulose readily differentiated from α-configured glucans 16 .…”

Cellulose from the green macroalgae Ulva lactuca: isolation, characterization, optotracing, and production of cellulose nanofibrils

“…The method utilizes optotracers, a class of molecular probes called oligothiophenes, which bind selectively to glucans producing a unique spectral pattern that identifies the bound target. Applying heptameric (Choong et al 2018) and pentameric (Choong et al 2019) optotracers, cellulose can be clearly distinguished from a range of glucans and glucose-containing heteropolysaccharides based on differences in size and stereochemistry. Here, we applied optotracing as a complementary tool to overcome the limitation of HPAEC-PAD and solidstate NMR to verify the polymeric origin of the detected xylose and glucose building blocks in the extracted cellulose.…”

“…Hence, the origin of xylose in the insoluble fraction of Ulva cell walls will be very difficult to determine. A novel method for carbohydrate analysis, optotracing, opens new possibilities to determine the spatial and compositional structure of polysaccharides in plant tissues (Choong et al 2016(Choong et al , 2018(Choong et al , 2019. Oligothiophenes bind selectively to glucans and produce unique spectral patterns that are recorded by excitation and emission fluorescence spectra and allow for new insights in the polysaccharide structure of biomass samples and plant tissues.…”

Electrospun cellulose acetate/gelatin nanofibrous wound dressing containing berberine for diabetic foot ulcer healing: in vitro and in vivo studies

“…Cellulose is one of the most abundant natural polymers on earth which has various derivative, but the most fascinating derivative is cellulose acetate (CA), the acetate ester form of cellulose [18][19][20]. CA is applicable in various applications such as membrane separation, biomedical, textile fibers, cigarette industries, and plastics [21][22][23][24]. The biomedical applications of CA are mainly categorized in drug delivery systems, tissue engineering, and wound dressing [25][26][27][28].…”