Advance in boronate affinity-based controllable orientedsurface imprinting

Abstract

Biomolecules, like antibody, aptamer and lectin, are still the main force for applications involved in selective separation and recognition. However, these biomolecules are usually suffered from many inevitable problems, such as hard to prepare, high cost, poor stability, as well as limited quantities. Molecular imprinting technique (MIT) as a robust biomimetic molecular recognition strategy to mimic the targeting ability of antibody and enzyme plays a significant role in many areas, including chemical separation, biosensing, catalysis, disease diagnosis, etc. Scientists have pay a lot of attention to developing advanced imprinting approaches to enable MIT adapt many more possible applications. Several user-friendly molecular imprinting methods, such as surface imprinting, epitope imprinting and emulsion imprinting, are hence developed to meet the high analytical requirements. Even so, facile MITs with wide-range versatility and high imprinting efficiency are extremely limited, which restrict the applicability of MIT. Boronate affinity-based controllable oriented surface imprinting (BACOSI) allows for easy and efficient preparation of molecularly imprinted polymers specific to saccharide compounds, which covering glycoproteins, glycopeptides, glycans and monosaccharides. In this paper, the principle, preparation process, applications and recent developments of BACOSI are briefly introduced. Three steps, namely template immobilization, oriented imprinting and template removal, are included in this approach. Template molecules (glycoprotein, glycopeptide, glycan or monosaccharide) immobilized on the surface of boronic-acid-functionalized substrate by virtue of boronate affinity interaction, followed by controllable self-polymerization of biocompatible monomer(s) to form an imprinting layer on the template-anchored substrate with tailored thickness in terms of molecule size of templates, and then the templates are effectively removed under suitable conditions (weak acidic solutions with or without surfactant are often utilized for templates removal). Imprinting in this approach is performed in a precise-controllable manner permitting the thickness of the imprinting layer to be fine-tuned via adjusting the imprinting time. This manner not only simplifies the imprinting procedure but also makes the approach widely applicable to a large range of sugar-containing biomolecules. Most of all, it can provide a guidance for design and preparation of other biomimetic molecular recognition materials, and a new level in methodology of MIT has been promoted by the presentation of this approach. In addition, some issues and future prospects of BACOSI are also presented in this paper based on our previous researches. From the viewpoint of preparation mechanism, template anchoring of BACOSI highly relies on the boronate affinity effect between boronic acid and cis-diol groups, thus it does not work for non-cis-diol-containing compounds. Exploiting some other means for template immobilization or template-anchoring-free imprinting modes is benefit for extending the application scope of BACOSI. Likewise, ideal biocompatibility and the ability of targeting are also significant for biological applications, for instance, cell imaging, clinical diagnosis and therapy. (Nevertheless, available aqueous phase polymerization for BACOSI is very limited, and its non-specific effect is also cannot be ignored when used for clinical analysis. The further study and exploration of imprinting system with negligible non-specific effect and suitable for the biomedical analysis is the key to form practical imprinting technology). In summary, BACOSI strategy just opens the pathway for the research and application based on facile and versatile imprinting technique in the future, there is still a long distance from being ready for use on industrial production and commercialization.