Nanogels open up access to a wide range of applications and offer among others hopeful approaches for use in the field of biomedicine. This review provides a brief overview of current developments of nanogels in general, particularly in the fields of drug delivery, therapeutic applications, tissue engineering, and sensor systems. Specifically, cyclodextrin (CD)‐based nanogels are important because they have exceptional complexation properties and are highly biocompatible. Nanogels as a whole and CD‐based nanogels in particular can be customized in a wide range of sizes and equipped with a desired surface charge as well as containing additional molecules inside and outside, such as dyes, solubility‐mediating groups or even biological vector molecules for pharmaceutical targeting. Currently, biological investigations are mainly carried out in vitro, but more and more in vivo applications are gaining importance. Modern molecular imaging methods are increasingly being used for the latter. Due to an extremely high sensitivity and the possibility of obtaining quantitative data on pharmacokinetic and pharmacodynamic properties, nuclear methods such as single photon emission computed tomography (SPECT) and positron emission tomography (PET) using radiolabeled compounds are particularly suitable here. The use of radiolabeled nanogels for imaging, but also for therapy, is being discussed.

Stable water-in-oil emulsion membranes can be prepared using [dilauryl(dimethyl)ammonium] bromide (DDAB), a cationic surfactant. We prepared ultrasmall cyclodextrin (γ-CyD) nanogels (γ-CyDngs) by forming ionic pairs between the secondary hydroxyl groups of γ-CyDs and DDAB. Fluorescence and NMR characterisation of the obtained γ-CyDngs revealed superior inclusion affinities compared with native γ-CyDs, beneficial for the solubilisation of hydrophobic compounds in water.

Cyclodextrins (CDs) are oligosaccharides composed of six (α), seven (β) or eight (γ) glucose units. Their inner hydrophobic cavity and hydrophilic external surface enable the formation of the “host-guest inclusion complex” with different organic or inorganic molecules showing high molecular selectivity. For these characteristics, CDs have many potential applications in electrochemical sensing. To enable CDs immobilization on the electrode surfaces, different chemical modifications are needed depending of the electrode material, while nanomaterials have been exploited to enhance the sensing signal. The CDs binding onto gold nanoparticles or carbon nanotubes, as an electron-transfer mediator to the electrode surface, is a typical example of it, while also graphene is largely used. The aim of the present review is to give an overview of CDs properties and their applications to electrochemical sensors for medical diagnostics. Different kinds for the functionalization of CDs onto electrode surfaces will be reviewed as well as their performance in presence of nanomaterials. Finally, CDs-based devices for sensing biomedical molecules of biomedical interest will be briefly presented and discussed.

Specifically designed electrochemical sensors are standing out as alternatives to enzyme-based biosensors for the sensing of metabolites. In our previous works, we developed a new electrochemical assay based on cyclodextrin supramolecular complexes. A ferrocene moiety (Fc) was chemically modified by phenylboronic acid (4-Fc-PB) and combined with two different kinds of cyclodextrins (CDs): β-CD and β-CD modified by a dipicolylamine group (dpa-p-HB-β-CDs) for the sensing of fructose and adenosine-triphosphate (ATP), respectively. The aim of the present work is to better comprehend the features underlining the aforementioned complex formation. For the first time, a study about inclusion phenomena between the 4-Fc-PB electroactive probe with β-CD and with dpa-p-HB-β-CD was performed by using nuclear magnetic resonance (NMR) analysis. In particular, we focused on providing insights on the interaction involved and on the calculation of the binding constant of 4-Fc-PB/β-CD supramolecular complex, and elucidation about a drift in the time observed during the control experiments of the electrochemical measurements for the 4-Fc-PB/dpa-p-HB-β-CD supramolecular complex. In this sense, this paper represents a step further in the explanation of the electrochemical results obtained, pointing out the nature of the interactions present both in the formation of the inclusions and in the sensing with the analytes.