Cyclodextrin-based nanosponges (CD-NS) are a novel class of polymers cross-linked with a three-dimensional network and can be obtained from cyclodextrins (CD) and pyromellitic dianhydride. Their properties, such as their ability to form an inclusion complex with drugs, can be used in biomedical science, as nanosponges influence stability, toxicity, selectivity, and controlled release. Most pharmaceutical research use CD-NS for the delivery of drugs in cancer treatment. Application of molecular targeting techniques result in increased selectivity of CD-NS; for example, the addition of disulfide bridges to the polymer structure makes the nanosponge sensitive to the presence of glutathione, as it can reduce such disulfide bonds to thiol moieties. Other delivery applications include dermal transport of pain killers or photosensitizers and delivery of oxygen to heart cells. This gives rise to the opportunity to transition to medical scaffolds, but more, in modern times, to create an ultrasensitive biosensor, which employs the techniques of surface-modified nanoparticles and molecularly imprinted polymers (MIP). The following review focuses on the biomedical research of cyclodextrin polymers cross-linked via dianhydrides of carboxylic acids.

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Recently a great interest in the field of protein engineering and the design of innovative drug delivery systems employing specific ligands such as cyclodextrins is observed. The paper reports the solid state, thermal method for protein coupling with β-cyclodextrin and the physicochemical and biological properties of the obtained conjugates. The structure of the obtained conjugates was investigated via liquid chromatography-mass spectrometry, dynamic light scattering and circular dichroism analysis. The presented conjugates were biologically active and covalently bound β-cyclodextrin preserved the ability to form inclusion complexes with the model compound. This report demonstrates the great potential of cyclodextrin as a modifying unit that can be used to modulate the properties of therapeutic proteins, additionally giving such conjugates the possibility to transport many therapeutic substances in the form of inclusion complexes. In addition, the paper presents the potential of protein-cyclodextrin conjugates to construct innovative bioactive molecules for biological and medical applications.Electronic supplementary materialThe online version of this article (doi:10.1007/s10847-017-0706-8) contains supplementary material, which is available to authorized users.

Water soluble highly anionic β-cyclodextrin-based polymers were synthesized by reaction between cyclodextrin oxyanion and pyromellitic anhydride. The synthesis method utilizes activation hydroxyl groups in anhydrous glucopyranosyl units (AGU) in the DMF solution with the use of NaH. In these conditions, like in the case of the cyclodextrin reactions in the highly alkaline media, there is a nucleophilic substitution of difunctional compounds, which develops a polymer network with various cyclodextrin substitution. Different molar ratios of the reagents were investigated in terms of molecular size, chemical structure and water solubility of the polymers. The separation of the polymer due to particle size by ultrafiltration process and HPSEC-MALLS-RI and MALDI-TOF MS measurements for molecular mass analysis were employed. The IR, H NMR, SEM, DSC and TG measurements were taken for the structural characterization of the polymers. Additionally, the solubility test and metal ion complexation processes were also investigated in a wide range of pH. These polymers could be used in several areas such as: improving the aqueous solubility of poor water-soluble molecules, removing heavy metals from waste water, protecting degradable substances or synthesizing new drug delivery systems.

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