Oligosaccharide Sensing in Aqueous Media by Porphyrin–Curdlan Conjugates: A Prêt‐á‐Porter Rather Than Haute‐Couture Approach

Saccharide sensing in aqueous media is an intriguing but challenging goal in current chemistry. Herein we report the oligosaccharide‐sensing behavior of newly synthesized porphyrin–curdlan conjugates, which are random coils in DMSO but become globules in aqueous solutions to induce circular dichroism (ICD) in the biologically accessible spectral region due to the conformational fixation of porphyrin reporters. The magnitude of ICD was significantly varied specifically in the presence of acarbose, a drug for type‐2 diabetes, enabling us to detect the aminosaccharide at concentrations down to 200 μm. This result demonstrates that the prêt‐á‐porter approach, using less‐defined reporter‐curdlan conjugates, is more advantageous than the traditional haute‐couture approach with highly sophisticated hosts in particular in oligosaccharide sensing. Ready to use: A random coil curdlan with moving porphyrin reporters in DMSO converts to globule curdlan‐saccharide co‐aggregate in aqueous media upon addition of saccharide, enabling the selective sensing of tetrasaccharide “acarbose”, a drug for diabetes and obesity, by using circular dichroism as read out responses for conformationally fixed porphyrins.