BSA-Sugar Conjugates as Ideal Building Blocks for SPR-Based Glycan Biosensors

Controlled immobilization of sugar probes is of key importance for the development of glycan biosensors. To this end, a series of BSA-sugar conjugates with different numbers of mannose units are prepared via the squaric acid-mediated coupling reaction. The conjugates can absorb directly on gold substrate without any derivation reactions, thus providing a simple and effective method for the construction of SPR-based glycan biosensors. SPR measurements show that the BSA-mannose conjugate with 11 mannoses exhibit the highest affinity to the lectin concanavalin A with a limit of detection of ca. 1.8 nM. Regeneration and specificity of the obtained glycan biosensors are also investigated

Fluorescent Neomannosyl Bovine Serum Albumin as Efficient Probe for Mannose Receptor Imaging and MCF‑7 Cancer Cell Targeting

Robust carbohydrate conjugated fluorescent bovine serum albumin (BSA) as useful tool to study carbohydrate–receptor interactions and in vivo targeting is reported. Amine terminated α-mannoside was attached to fluorescein labeled BSA via diethyl squarate strategy. The surface functionalization and lectin binding specific to fluorescent neomannosyl glycoprotein were confirmed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS), surface plasmon resonance (SPR), and microarray imaging. The glycoconjugate was further used to image concanavalin A (ConA), pili of <i>E. coli</i> K12, and lysosomes in MCF-7 cancerous cells successfully, suggesting that this neomannosyl glycoprotein can be used as suitable probe to elucidate carbohydrate–protein interactions, image cancers, and target drug specifically toward tumors