Joseph T. Delaney

Nanoprecipitation and nanoformulation of polymers: from history to powerful possibilities beyond poly(lactic acid)

Nanoprecipitation is a facile, mild, and low energy input process for the preparation of polymeric nanoparticles. Basic requirements, as well as common techniques for the self-assembly of non-charged and non-amphiphilic macromolecules into defined nanoparticles are described. At present, the primary focus of polymer nanoprecipitation research lays on poly(lactic acid) (PLA) and its copolymer poly(lactic-co-glycolic acid) (PLGA). This contribution thus emphasises on polymers beyond PLA systems, such as common industrial- or tailored lab-made polymers, and their ability to form well-defined, functional nanoparticles for a variety of applications now and in the past two centuries. Moreover, in combination with high-throughput devices such as microfluidics, pipetting robots, inkjet printers, and automated analytical instrumentation, the abilities of nanoprecipitation may broaden tremendously with significant effects on new applications.

Inkjet printing of proteins

This article presents a review of the current status of the use of inkjet technology with protein-related applications. It includes a brief history of inkjet printing, discusses the advantages of employing the technology with proteins, using a number of selected applications as illustration, and concludes with a view of future research directions.

Reactive inkjet printing of polyurethanes

Reactive inkjet printing technology was used to create micron-scale polyurethane structures, such as dots, lines and pyramids. These structures were fabricated insitu and cured within five minutes by inkjet printing two separate inks successively from two separate print heads, with one ink containing isophorone diisocyanate, and the other consisting of an oligomer of poly(propylene glycol), a catalyst, and a cross-linking agent. The fast polymerization reaction that forms polyurethane at the surface opens a new route for rapid prototyping, as well as the use of inkjet printing as a technique for handling moisture-sensitive reactions. By the addition of fluorescent dyes to the polyol ink, confocal laser scanning fluorescence microscopy was used to investigate the miscibility behavior of both solutions on the substrate.

Reactive inkjet printing of calcium alginate hydrogel porogens—a new strategy to open-pore structured matrices with controlled geometry

Taking advantage of inkjets ability to dispense uniform droplets in the picolitre/nanolitre ranges of volumes, we have generated reversible hydrogel porogen beads using reactive printing, which we use as templates for creating networks of pores with monomodally distributed pore sizes.

Examination and optimization of the self-assembly of biocompatible, polymeric nanoparticles by high-throughput nanoprecipitation

In recent years, the development of polymer nanoparticle suspensions by nanoprecipitation has gained increased attention both by industry and academia. However, the process by which such formulations are prepared is a highly empirically driven enterprise, whereby developing optimized formulations remains an iterative process. In this contribution, a new approach towards exploration of the materials space for these systems is reported, based on systematically varying processing and formulation to understand their influence on the characteristics of the resulting materials. Taking advantage of the tools and techniques that have already been standardized by informatics-driven life sciences disciplines, we have prepared libraries of nanoparticle formulations of poly(methyl methacrylate-stat-acrylate), poly(lactic-co-glycolic acid), and acetal-derivatized dextran by using a pipetting robot. They were subsequently characterized using a dynamic light scattering plate reader, analytical ultracentrifugation, and scanning electron microscopy. With this high-throughput nanoprecipitation approach, large numbers of materials can be prepared, screened, and the formulation rationally optimized.

A Practical Approach to the Development of Inkjet Printable Functional Ionogels—Bendable, Foldable, Transparent, and Conductive Electrode Materials

Ionic liquid gels, or ionogels, are semi-conductive, flexible materials, offering a host of tunable physical properties, gaining an increasing level of scientific interest. One of the challenges of this emerging category of materials is that the structure-process-property relationships are still empirically driven. In this study, a simple, practical approach is laid out to prepare standardized libraries of these materials, for the purpose of selecting transparent, flexible conductive formulations that can be dispensed using inkjet printing. The net result of this was the optimization of a PEG-DMA ionogel formulation exhibiting an optical transparency that was greater than 94% from near-UV to near-IR from a 150 µm thick films, and a resistivity of 12.4 Ω · m.

Combinatorial Optimization of Multiple MALDI Matrices on a Single Tissue Sample Using Inkjet Printing

Taking advantage of the drop-on-demand capabilities of inkjet printing, the first example of a single tissue being used as a substrate for preparing combinatorial arrays of different matrix-assisted laser desorption/ionization (MALDI) matrices in multiple concentrations on a single chip is reported. By varying the number of droplets per spot that were printed, a gradient array of different amounts of matrix material could be printed on a single chip, while the selection of matrices could be adjusted by switching different matrix materials. The result was a two-dimensional array of multiple matrices on a single tissue slice, which could be analyzed microscopically and by MALDI to elucidate which combination of matrix and printing conditions offered the best resolution in terms of spot-to-spot distance and signal-to-noise ratios for proteins in the recorded MS spectra. This combinatorial approach enables the efficient optimization of possible matrices in an organized, side-by-side array format, which can particularly be useful for the detection of specific protein markers.

Fast high-throughput screening of temoporfin-loaded liposomal formulations prepared by ethanol injection method

A new strategy for fast, convenient high-throughput screening of liposomal formulations was developed, utilizing the automation of the so-called ethanol-injection method. This strategy was illustrated by the preparation and screening of the liposomal formulation library of a potent second-generation photosensitizer, temoporfin. Numerous liposomal formulations were efficiently prepared using a pipetting robot, followed by automated size characterization, using a dynamic light scattering plate reader. Incorporation efficiency of temoporfin and zeta potential were also detected in selected cases. To optimize the formulation, different parameters were investigated, including lipid types, lipid concentration in injected ethanol, ratio of ethanol to aqueous solution, ratio of drug to lipid, and the addition of functional phospholipid. Step-by-step small liposomes were prepared with high incorporation efficiency. At last, an optimized formulation was obtained for each lipid in the following condition: 36.4 mg·mL−1 lipid, 13.1 mg·mL−1 mPEG2000-DSPE, and 1:4 ethanol:buffer ratio. These liposomes were unilamellar spheres, with a diameter of approximately 50 nm, and were very stable for over 20 weeks. The results illustrate this approach to be promising for fast high-throughput screening of liposomal formulations.

Printed conductive features for DNA chip applications prepared on PET without sintering

We present here an innovative and cheap alternative for the preparation of conductive tracks printed on flexible polymer substrates at room temperature. For this purpose, we applied a combination of a Tollens reagent-based silver deposition and printed mask, using an office laser printer. The as-prepared conductive structures were used for DNA chip fabrication. The great advantage of the presented method is that the conductive features can be fabricated in a facile and inexpensive way, while maintaining the high flexibility to tailor the design to its application. The DNA chips showed the same response as well as sensitivity compared to chips made conventionally by photolithography or screen printing.