Alessandra Zizzari

Radiochemistry on chip

We have developed an integrated microfluidic platform for producing 2-[(18)F]-fluoro-2-deoxy-D-glucose ((18)F-FDG) in continuous flow from a single bolus of radioactive isotope solution, with constant product yields achieved throughout the operation that were comparable to those reported for commercially available vessel-based synthesisers (40-80%). The system would allow researchers to obtain radiopharmaceuticals in a dose-on-demand setting within a few minutes. The flexible architecture of the platform, based on a modular design, can potentially be applied to the synthesis of other radiotracers that require a two-step synthetic approach, and may be adaptable to more complex synthetic routes by implementing additional modules. It can therefore be employed for standard synthesis protocols as well as for research and development of new radiopharmaceuticals.

Catalytic Self‐Propulsion of Supramolecular Capsules Powered by Polyoxometalate Cargos

Multicompartment, spherical microcontainers were engineered through a layer-by-layer polyelectrolyte deposition around a fluorescent core while integrating a ruthenium polyoxometalate (Ru4POM), as molecular motor, vis-à-vis its oxygenic, propeller effect, fuelled upon H2O2 decomposition. The resulting chemomechanical system, with average speeds of up to 25 μm s(-1), is amenable for integration into a microfluidic set-up for mixing and displacement of liquids, whereby the propulsion force and the resulting velocity regime can be modulated upon H2O2-controlled addition.

An SPR based immunoassay for the sensitive detection of the soluble epithelial marker E-cadherin

Protein biomarkers are important diagnostic tools for cancer and several other diseases. To be validated in a clinical context, a biomarker should satisfy some requirements including the ability to provide reliable information on a pathological state by measuring its expression levels. In parallel, the development of an approach capable of detecting biomarkers with high sensitivity and specificity would be ideally suited for clinical applications. Here, we performed an immune-based label free assay using Surface Plasmon Resonance (SPR)-based detection of the soluble form of E-cadherin, a cell-cell contact protein that is involved in the maintaining of tissue integrity. With this approach, we obtained a specific and quantitative detection of E-cadherin from a few hundred microliters of serum of breast cancer patients by obtaining a 10-fold enhancement in the detection limit over a traditional colorimetric ELISA.

Highly sensitive Membrane-based Pressure Sensors (MePS) for real-time monitoring of catalytic reactions

Functional, flexible, and integrated lab-on-chips, based on elastic membranes, are capable of fine response to external stimuli, so to pave the way for many applications as multiplexed sensors for a wide range of chemical, physical and biomedical processes. Here, we report on the use of elastic thin membranes (TMs), integrated with a reaction chamber, to fabricate a membrane-based pressure sensor (MePS) for reaction monitoring. In particular, the TM becomes the key-element in the design of a highly sensitive MePS capable to monitor gaseous species production in dynamic and temporally fast processes with high resolution and reproducibility. Indeed, we demonstrate the use of a functional MePS integrating a 2 μm thick polydimethylsiloxane TM by monitoring the dioxygen evolution resulting from catalytic hydrogen peroxide dismutation. The operation of the membrane, explained using a diffusion-dominated model, is demonstrated on two similar catalytic systems with catalase-like activity, assembled into polyelectrolyte multilayers capsules. The MePS, tested in a range between 2 and 50 Pa, allows detecting a dioxygen variation of the μmol L-1 s-1 order. Due to their structural features, flexibility of integration, and biocompatibility, the MePSs are amenable of future development within advanced lab-on-chips.

One step preparation of quantum dot-embedded lipid nanovesicles by a microfluidic device

Synthetic carriers that mimic “natural lipid-based vesicles” (such as micro/nanovesicles, exosomes) have found broad applications in biomedicine for the delivery of biomolecules and drugs. Remarkable advantages of using synthetic carriers include control over the lipid composition, structure and size, together with the possibility to add tracer molecules to monitor their in situ distribution via fluorescence microscopy. Over the past few years, new methods of vesicles production have been developed and optimized, such as those based on microfluidic techniques. These innovative approaches allow us to overcome the limitations faced in conventional methods of liposome preparation, such as size distribution and polydispersity. Herein, a Microfluidic Hydrodynamic Focusing (MHF) device has been used for the production of lipid-based vesicles with different lipid combinations that resemble natural exosomes, such as phosphatidylcholines (PC), cholesterol (Chol), dicetyl phosphate (DCP) and ceramide (Cer). Thanks to a fine control on fluid manipulation, the MHF device allows preparation of vesicles with controlled size, a relevant feature in the emerging field of carrier-assisted cell-delivery. Interestingly, PC/Chol/Cer vesicles exhibit low polydispersity and high stability up to 45 days. Later, quantum dots (QDs) were successfully embedded in these vesicles through the same preparation process. The development of QD-embedded lipid nanovesicles by MHF devices has never been described previously.

Continuous-Flow Production of Injectable Liposomes via a Microfluidic Approach

Injectable liposomes are characterized by a suitable size and unique lipid mixtures, which require time-consuming and nonstraightforward production processes. The complexity of the manufacturing methods may affect liposome solubility, the phase transition temperatures of the membranes, the average particle size, and the associated particle size distribution, with a possible impact on the drug encapsulation and release. By leveraging the precise steady-state control over the mixing of miscible liquids and a highly efficient heat transfer, microfluidic technology has proved to be an effective and direct methodology to produce liposomes. This approach results particularly efficient in reducing the number of the sizing steps, when compared to standard industrial methods. Here, Microfluidic Hydrodynamic Focusing chips were produced and used to form liposomes upon tuning experimental parameters such as lipids concentration and Flow-Rate-Ratios (FRRs). Although modelling evidenced the dependence of the laminar flow on the geometric constraints and the FRR conditions, for the specific formulation investigated in this study, the lipids concentration was identified as the primary factor influencing the size of the liposomes and their polydispersity index. This was attributed to a predominance of the bending elasticity modulus over the vesiculation index in the lipid mixture used. Eventually, liposomes of injectable size were produced using microfluidic one-pot synthesis in continuous flow.