Development of a microfluidic "click chip" incorporating an immobilized Cu(I) catalyst

Palladium nanoparticles immobilized on polyethylenimine-derivatized gold surfaces for catalysis of Suzuki reactions: development and application in a lab-on-a-chip context

Gold surface-bound hyperbranched polyethyleneimine (PEI) films decorated with palladium nanoparticles have been used as efficient catalysts for a series of Suzuki reactions. This thin film-format demonstrated good catalytic efficiency (TON up to 3.4 × 10³) and stability. Incorporation into a quartz crystal microbalance (QCM) instrument illustrated the potential for using this approach in lab-on-a-chip-based synthesis applications.

Gold surface-bound hyperbranched polyethyleneimine (PEI) films decorated with palladium nanoparticles have been used as efficient catalysts for a series of Suzuki reactions in a lab-on-a-chip format.

Click chemistry at the microscale

This manuscript reviews recent developments in click chemistry in microscale systems.

Recent Advances in Recoverable Systems for the Copper-Catalyzed Azide-Alkyne Cycloaddition Reaction (CuAAC)

The explosively-growing applications of the Cu-catalyzed Huisgen 1,3-dipolar cycloaddition reaction between organic azides and alkynes (CuAAC) have stimulated an impressive number of reports, in the last years, focusing on recoverable variants of the homogeneous or quasi-homogeneous catalysts. Recent advances in the field are reviewed, with particular emphasis on systems immobilized onto polymeric organic or inorganic supports.

Microfluidic Preparation of a 89Zr-Labeled Trastuzumab Single-Patient Dose

(89)Zr-labeled antibodies are being investigated in several clinical trials; however, the time requirement for synthesis of clinical doses can hinder patient throughput because of scheduling difficulties. Additionally, low specific activity due to poor labeling efficiency can require larger amounts of the radiopharmaceutical to be administered, possibly leading to adverse side effects. Here, we describe the design and evaluation of a microfluidic reactor capable of synthesizing a single clinical dose of (89)Zr-labeled antibody. (89)Zr-labeled trastuzumab was chosen for this validation because it is currently being evaluated in clinical trials for imaging human epidermal growth factor receptor 2-positive cancer patients.

METHODS

A microreactor fabricated from polydimethylsiloxane/glass was silanated with trimethoxy(octadecyl) silane to reduce antibody adsorption. Desferrioxamine-p-benzyl-isothiocyanate (DFO-Bz-NCS) was conjugated to trastuzumab in an 8:1 molar ratio following the literature procedures using aseptic techniques. Radiolabeling was performed by pumping (89)Zr-oxalate and DFO-Bz-trastuzumab into the microfluidic reactor at a total rate of 20 μL/min in ratios varying from 1:37 to 1:592 mg:MBq at 37°C to achieve optimal labeling.

RESULTS

Silanated reactors showed low antibody adsorption in comparison to unmodified reactors (95% monoclonal antibody recovered vs. 0% recovered). Labeling of the modified trastuzumab was shown to be achievable at a specific activity above the reported literature value of 220 MBq/mg. A high radiochemical purity was achieved without an incubation period at specific activities of less than 148 MBq/mg; however, specific activities up to 592 MBq/mg could be achieved with an incubation period. Clinical doses were able to be prepared and passed all quality control guidelines set by the Food and Drug Administration. Samples were sterile, colorless, and radiochemically pure (100%); maintained the ability to bind to the intended receptor; formed a minimal amount of aggregates (1%-4%); and were completed within 45-60 min.

CONCLUSION

(89)Zr-labeled trastuzumab for use in a clinical setting was synthesized in a microfluidic reactor in under an hour while reducing the amount of handling required by a technician. Use of this compact platform not only could enable the use of radiolabeled antibodies to become a common practice, but also could spread the use of radiolabeled antibodies beyond locations with cyclotron facilities.

An injectable PEG-based hydrogel synthesized by strain-promoted alkyne–azide cycloaddition for use as an embolic agent

Cyclooctyne and azide functionalized PEGs are prepared by ring-opening polymerization. They form a biodegradable hydrogel in situ to temporarily block rabbit ear vessels.

Synthesis of the copper chelator TGTA and evaluation of its ability to protect biomolecules from copper induced degradation during copper catalyzed azide-alkyne bioconjugation reactions

One of the most successful bioconjugation strategies to date is the copper(I)-catalyzed cycloaddition reaction (CuAAC), however, the typically applied reaction conditions have been found to degrade sensitive biomolecules. Herein, we present a water soluble copper chelator which can be utilized to protect biomolecules from copper induced degradation.

Diffusion phenomena of cells and biomolecules in microfluidic devices

Biomicrofluidics is an emerging field at the cross roads of microfluidics and life sciences which requires intensive research efforts in terms of introducing appropriate designs, production techniques, and analysis. The ultimate goal is to deliver innovative and cost-effective microfluidic devices to biotech, biomedical, and pharmaceutical industries. Therefore, creating an in-depth understanding of the transport phenomena of cells and biomolecules becomes vital and concurrently poses significant challenges. The present article outlines the recent advancements in diffusion phenomena of cells and biomolecules by highlighting transport principles from an engineering perspective, cell responses in microfluidic devices with emphases on diffusion- and flow-based microfluidic gradient platforms, macroscopic and microscopic approaches for investigating the diffusion phenomena of biomolecules, microfluidic platforms for the delivery of these molecules, as well as the state of the art in biological applications of mammalian cell responses and diffusion of biomolecules.

Flow chemistry as a versatile tool for the synthesis of triazoles

This review surveys the continuous-flow strategies for the synthesis of triazoles by means of copper-catalyzed and catalyst-free cycloadditions between azides and various dipolarophiles.