Tear Glucose Sensor Development

Clinical Evidence for Use of a Noninvasive Biosensor for Tear Glucose as an Alternative to Painful Finger-Prick for Diabetes Management Utilizing a Biopolymer Coating

Alicja E. Kownacka, Dovile Vegelyte, Maurits Joosse, Nicoleta Anton, B. Jelle Toebes, Jan Lauko, Irene Buzzacchera, Katarzyna Lipinska, Daniela A. Wilson, Nel Geelhoed-Duijvestijn, and Christopher J. Wilson

ABSTRACT: Diabetes is a metabolic condition that is exponentially increasing worldwide. Current monitoring methods for diabetes are invasive, painful, and expensive. Herein, we present the first multipatient clinical trial that demonstrates clearly that tear fluid may be a valuable marker for systemic glucose measurements. The NovioSense Glucose Sensor, worn under the lower eye lid (inferior conjunctival fornix), is reported to continuously measure glucose levels in the basal tear fluid with good correlation to blood glucose values, showing clear clinical feasibility in both animals and humans. Furthermore, the polysaccharide coated device previously reported by our laboratory when worn, does not induce pain or irritation. In a phase II clinical trial, six patients with type 1 Diabetes Mellitus were enrolled and the capability of the device to measure glucose in the tear fluid was evaluated. The NovioSense Glucose Sensor gives a stable signal and the results correlate well to blood glucose values obtained from finger-prick measurements determined by consensus error grid analysis.


Polymer Brush-Functionalized Chitosan Hydrogels as Antifouling Implant Coatings

Irene Buzzacchera, Mariia Vorobii, Nina Yu. Kostina, Andres de los Santos Pereira, Tomaś̌Riedel, Michael Bruns, Wojciech Ogieglo, Martin Möller, Christopher J. Wilson* and Cesar Rodriguez-Emmenegger*

Implantable sensor devices require coatings that efficiently interface with the tissue environment to mediate biochemical analysis. In this regard, bioinspired polymer hydrogels offer an attractive and abundant source of coating materials. However, upon implantation these materials generally elicit inflammation and the foreign body reaction as a consequence of protein fouling on their surface and concomitant poor hemocompatibility. In this report we investigate a strategy to endow chitosan hydrogel coatings with antifouling properties by the grafting of polymer brushes in a “grafting-from” approach. Chitosan coatings were functionalized with polymer brushes of oligo(ethylene glycol) methyl ether methacrylate and 2-hydroxyethyl methacrylate using photoinduced single electron transfer living radical polymerization and the surfaces were thoroughly characterized by XPS, AFM, water contact angle goniometry, and in situ ellipsometry. The antifouling properties of these new bioinspired hydrogel-brush coatings were investigated by surface plasmon resonance. The influence of the modifications to the chitosan on hemocompatibility was assessed by contacting the surfaces with platelets and leukocytes. The coatings were hydrophilic and reached a thickness of up to 180 nm within 30 min of polymerization. The functionalization of the surface with polymer brushes significantly reduced the protein fouling and eliminated platelet activation and leukocyte adhesion. This methodology offers a facile route to functionalizing implantable sensor systems with antifouling coatings that improve hemocompatibility and pave the way for enhanced device integration in tissue.


Wireless Tear Glucose Sensor

A. Hennig, J. Lauko, A. Grabmaier, C. J. Wilson

This paper presents a novel wireless tear glucose level sensor for diabetes patients. The miniaturized sensor can be worn non– invasively under the eye lid. It is composed of a chronoamperometric glucose sensor and an ASIC set with integrated potentiostat and transponder circuits. Wireless energy and data transmission according to the passive transponder standard ISO18000-3 is used to power and readout the sensor. A special coil shape enables high comfort for the patient. High integration level is achieved by a combination of antenna and sensor electrode wires. A complete demonstrator system including ASIC and sensor fabrication as well as assembly was manufactured and the function is demonstrated.


Exploring functional pairing between surface glycoconjugates and human galectins using programmable glycodendrimersomes

Qi Xiao, Anna-Kristin Ludwig, Cecilia Romanò, Irene Buzzacchera, Samuel E. Sherman, Maria Vetro, Sabine Vértesy, Herbert Kaltner, Ellen H. Reed, Martin Möller, Christopher J. Wilson, Daniel A. Hammer, Stefan Oscarson, Michael L. Klein, Hans-Joachim Gabius, and Virgil Percec

Precise translation of glycan-encoded information into cellular activity depends critically on highly specific functional pairing between glycans and their human lectin counter receptors. Sulfoglycolipids, such as sulfatides, are important glycolipid components of the biological membranes found in the nervous and immune systems. The optimal molecular and spatial design aspects of sulfated and nonsulfated glycans with high specificity for lectin-mediated bridging are unknown. To elucidate how different molecular and spatial aspects combine to ensure the high specificity of lectin-mediated bridging, a bottom-up toolbox is devised. To this end, negatively surface-charged glycodendrimersomes (GDSs), of different nanoscale dimensions, containing sulfo-lactose groups are self-assembled in buffer from a synthetic sulfatide mimic: Janus glycodendrimer (JGD) containing a 3′-Osulfo-lactose headgroup. Also prepared for comparative analysis are GDSs with nonsulfated lactose, a common epitope of human membranes. These self-assembled GDSs are employed in aggregation assays with 15 galectins, comprising disease-related human galectins, and other natural and engineered variants from four families, having homodimeric, heterodimeric, and chimera architectures. There are pronounced differences in aggregation capacity between human homodimeric and heterodimeric galectins, and also with respect to their responsiveness to the charge of carbohydrate-derived ligand. Assays reveal strong differential impact of ligand surface charge and density, as well as lectin concentration and structure, on the extent of surface cross-linking. These findings demonstrate how synthetic JGD-headgroup tailoring teamed with protein engineering and network assays can help explain how molecular matchmaking operates in the cellular context of glycan and lectin complexity.


Review Articles Written by NovioSense

Sensor Devices Inspired by the Five Senses: A Review

Mila I. Svechtarova, Irene Buzzacchera, B. Jelle Toebes, Jan Lauko, Nicoleta Anton, and Christopher J. Wilson

Wearable devices (wearables) have recently gained significant traction and are predicted to dominate many areas of research over the next 5 years. Many wearables contain a host of sensors that feedback vital bodily parameters to a central system. Although many artificial sensors exist, the biggest challenge to medical wearables is to interface and harness the “big data” set from the human bodies own complex sensor network to better allow early diagnosis and/or treatment and prevention of diseases that have a huge economic burden on society such as type II diabetes. Cybernetics and medicine are joining their forces to overcome the new challenges in developing smarter, more intuitive and smaller sensors that interface with the human sensory system. This review is focused on the interface of devices to ion‐mediated transduction pathways both through G‐Coupled Protein Receptors and direct or mechanically transduced ion pathways.


Marie Curie Funded Projects

Screening Libraries of Amphiphilic Janus Dendrimers Based on Natural Phenolic Acids to Discover Monodisperse Unilamellar Dendrimersomes

Irene Buzzacchera, Qi Xiao, Hong Han, Khosrow Rahimi, Shangda Li, Nina Yu. Kostina, B. Jelle Toebes, Samantha E Wilner, Martin Moeller, Cesar Rodriguez-Emmenegger, Tobias Baumgart, Daniela A. Wilson, Christopher J. Wilson, Michael L. Klein, and Virgil Percec

Natural, including plant, and synthetic phenolic acids are employed as building blocks for the synthesis of constitutional isomeric libraries of self-assembling dendrons and dendrimers that are the simplest examples of programmed synthetic macromolecules. Amphiphilic Janus dendrimers are synthesized from a diversity of building blocks including natural phenolic acids. They self-assemble in water or buffer into vesicular dendrimersomes employed as biological membrane mimics, hybrid and synthetic cells. These dendrimersomes are predominantly unilamellar or multilamellar vesicles with size and polydispersity that is predicted by their primary structure. However, in numerous cases unilamellar dendrimersomes completely free of multilamellar assemblies are desirable. Here we report the synthesis and structural analysis of a library containing 13 amphiphilic Janus dendrimers containing linear and branched alkyl chains on their hydrophobic part. They were prepared by an optimized iterative modular synthesis starting from natural phenolic acids. Monodisperse dendrimersomes were prepared by injection and giant polydisperse by hydration. Both were structurally characterized to select the molecular design principles that provide unilamellar dendrimersomes in higher yields and shorter reaction times than under previously used reaction conditions. These dendrimersomes are expected to provide important tools for synthetic cell biology, encapsulation and delivery.


3D Printing of Thermoresponsive Polyisocyanide (PIC) Hydrogels as Bioink and Fugitive Material for Tissue Engineering

Nehar Celikkin, Joan Simó Padial, Marco Costantini, Hans Hendrikse, Rebecca Cohn, Christopher J. Wilson, Alan Edward Rowan and Wojciech Święszkowski

Despite the rapid and great developments in the field of 3D hydrogel printing, a major ongoing challenge is represented by the development of new processable materials that can be effectively used for bioink formulation. In this work, we present an approach to 3D deposit, a new class of fully-synthetic, biocompatible PolyIsoCyanide (PIC) hydrogels that exhibit a reverse gelation temperature close to physiological conditions (37 °C). Being fully-synthetic, PIC hydrogels are particularly attractive for tissue engineering, as their properties—such as hydrogel stiffness, polymer solubility, and gelation kinetics—can be precisely tailored according to process requirements. Here, for the first time, we demonstrate the feasibility of both 3D printing PIC hydrogels and of creating dual PIC-Gelatin MethAcrylate (GelMA) hydrogel systems. Furthermore, we propose the use of PIC as fugitive hydrogel to template structures within GelMA hydrogels. The presented approach represents a robust and valid alternative to other commercial thermosensitive systems—such as those based on Pluronic F127—for the fabrication of 3D hydrogels through additive manufacturing technologies to be used as advanced platforms in tissue engineering.


SET-LRP in biphasic mixtures of fluorinated alcohols with water

Adrian Moreno, Tong Liu, Liang Ding, Irene Buzzacchera, Marina Galià, Martin Möller, Christopher J. Wilson, Gerard Lligadasa and Virgil Percec

Biphasic-binary mixtures of 2,2,2-trifluoroethanol (TFE) or 2,2,3,3-tetrafluoropropanol (TFP) with water were used as reaction media to synthesize well-defined poly(methyl acrylate) (PMA) with chain end functionality close to 100% by SET-LRP. Non-activated Cu(0) wire was used as a catalyst, taking advantage of the Cu(0)-activation property that these fluorinated alcohols possess. Biphasic-binary mixtures of water, containing a ligand and Cu(II)Br2 either generated by disproportionation of Cu(I)Br or externally added, and an organic solvent, containing a monomer and a polymer, were studied. Two N-ligands were investigated: the classic tris(2-dimethylaminoethyl)amine (Me6-TREN) and tris(2-aminoethyl)amine (TREN), as a more economically attractive alternative for technological purposes. The results reported here support the replacement of Me6-TREN by TREN, taking into account the fact that the latter requires small loadings of an externally added Cu(II)Br2 deactivator and a ligand in the water phase to mediate a living radical polymerization process. Both catalytic systems ensure efficient SET-LRP processes with first order kinetics to high conversion, linear dependence of experimental Mn on conversion, narrow molecular weight distribution, and near-quantitative chain end functionality.

Polyisocyanopeptide hydrogels: a novel thermo-responsive hydrogel supporting pre-vascularization and the development of organotypic structures

Jakub Zimoch, Joan Simó Padial, Agnes S. Klar, Queralt Vallmajo-Martin, Martin Meuli, Thomas Biedermann, Christopher J. Wilson, Alan Rowan and Ernst Reichmann

Molecular and mechanical interactions with the 3D extracellular matrix are essential for cell functions such as survival, proliferation, migration, and differentiation. Thermo-responsive biomimetic polyisocyanopeptide (PIC) hydrogels are promising new candidates for 3D cell, tissue, and organ cultures. This is a synthetic, thermo-responsive and stress-stiffening material synthesized via polymerization of the corresponding monomers using a nickel perchlorate as a catalyst. It can be tailored to meet various demands of cells by modulating its stiffness and through the decoration of the polymer with short GRGDS peptides using copper free click chemistry. These peptides make the hydrogels biocompatible by mimicking the binding sites of certain integrins.

This study focuses on the optimization of the PIC polymer properties for efficient cell, tissue and organ development. Screening for the optimal stiffness of the hydrogel and the ideal concentration of the GRGDS ligand conjugated with the polymer, enabled cell proliferation, migration and differentiation of various primary cell types of human origin. We demonstrate that fibroblasts, endothelial cells, adipose-derived stem cells and melanoma cells, do survive, thrive and differentiate in optimized PIC hydrogels. Importantly, these hydrogels support the spontaneous formation of complex structures like blood capillaries in vitro. Additionally, we utilized the thermo-responsive properties of the hydrogels for a rapid and gentle recovery of viable cells. Finally, we show that organotypic structures of human origin grown in PIC hydrogels can be successfully transplanted subcutaneously onto immune-compromised rats, on which they survive and integrate into the surrounding tissue.