Brian Creran

Colorimetric Protein Sensing Using Catalytically Amplified Sensor Arrays

Catalytically active iron oxide nanoparticles are used as recognition elements and signal amplifiers for the array-based colorimetric sensing of proteins. Interactions between cationic monolayers on the Fe(3) O(4) NPs and analyte proteins differentially modulates the peroxidase-like activity of Fe(3) O(4) NPs, affording catalytically amplified colorimetric signal patterns that enable the detection and identification of proteins at 50 nM.

Controlled and Sustained Release of Drugs from Dendrimer-Nanoparticle Composite Films

A dendrimer-nanoparticle hybrid scaffold based on robust dithiocarbamate formation provides a controlled drug delivery system. These composite films are nontoxic and can incorporate a variety of guests, providing sustained drug release over multiple uses. The system is highly modular: the release process can be easily tuned by altering the dendrimer generation and the size of the AuNPs, generating a versatile delivery system.

Detection of bacteria using inkjet-printed enzymatic test strips.

Low-cost diagnostics for drinking water contamination have the potential to save millions of lives. We report a method that uses inkjet printing to copattern an enzyme–nanoparticle sensor and substrate on a paper-based test strip for rapid detection of bacteria. A colorimetric response is generated on the paper substrate that allows visual detection of contamination without the need for expensive instrumentation. These strips demonstrate a viable nanomanufacturing strategy for low-cost bacterial detection.

Chemically Directed Immobilization of Nanoparticles onto Gold Substrates for Orthogonal Assembly Using Dithiocarbamate Bond Formation

Dithiocarbamate-mediated bond formation combined with soft lithography was used for the selective immobilization of amine-functionalized silica nanoparticles on gold substrates. The available amine groups on the upper surface of the immobilized silica nanoparticles were further utilized for postdeposition of additional materials including particles, dyes, and biomolecules. The robustness of dithiocarbamate-mediated immobilization enables orthogonal assembly on surfaces via selective removal of the masking thiol ligands using iodine vapor etching followed by further functionalization.

Direct Patterning of Engineered Ionic Gold Nanoparticles via Nanoimprint Lithography

Gold nanoparticles are engineered for direct imprinting of stable structures. This imprinting strategy provides access to new device architectures, as demonstrated through the fabrication of a prototype photoswitchable device.

Cell Alignment using Patterned Biocompatible Gold Nanoparticle Templates

Biocompatible structures are produced for cellular patterning. The biocompatible surfaces are generated to provide protein nonfouling patterns, offering direct communication to the cells for controlling cell adhesion and proliferation. These biofunctional surfaces provide a platform for aligning the cells in the direction of patterns, indicating potential application in the field of tissue engineering.

Inkjet-Printed Gold Nanoparticle Surfaces for the Detection of Low Molecular Weight Biomolecules by Laser Desorption/Ionization Mass Spectrometry

AbstractEffective detection of low molecular weight compounds in matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) is often hindered by matrix interferences in the low m/z region of the mass spectrum. Here, we show that monolayer-protected gold nanoparticles (AuNPs) can serve as alternate matrices for the very sensitive detection of low molecular weight compounds such as amino acids. Amino acids can be detected at low fmol levels with minimal interferences by properly choosing the AuNP deposition method, density, size, and monolayer surface chemistry. By inkjet-printing AuNPs at various densities, we find that AuNP clusters are essential for obtaining the greatest sensitivity. Graphical Abstractᅟ

Tunable Elastic Modulus of Nanoparticle Monolayer Films by Host–Guest Chemistry

The elastic modulus of an ultrathin nanoparticle (NP) monolayer film is tuned by modulating the binding strength between the NPs on a molecular level. NP monolayer films constructed by crosslinking NPs of different binding affinities are fabricated at oil/water interfaces. By inducing buckling patterns on these films, the correlation between the binding affinity of the NPs and the elastic modulus is investigated.

Gradient and Patterned Protein Films Stabilized via Nanoimprint Lithography for Engineered Interactions with Cells

Protein-based biomaterials provide versatile scaffolds for generating functional surfaces for biomedical applications. However, tailoring the functional and biological properties of protein films remains a challenge. Here, we describe a high-throughput method to designing stable, functional biomaterials by combining inkjet deposition of protein inks with a nanoimprint lithography based methodology. The translation of the intrinsically charged proteins into functional materials properties was demonstrated through controlled cellular adhesion. This modular strategy offers a rapid method to produce customizable biomaterials.

Polymer – Nanoparticle Assemblies for Array Based Sensing

Sensing clinically relevant biomolecules is crucial for the detection and prevention of disease. Currently used detection methods tend to be expensive, time intensive, and specific for only one particular biomolecule of interest. Nanoparticle-based arrays using conjugated polymers have emerged as an analytical and potential clinical tool, allowing detection of a wide range of biomolecules using selective, not specific, sensor components. In this report, we highlight recent progress in nanoparticle - polymer sensor arrays in both the fundamental understanding of how the sensor arrays function as well as the detection of clinically relevant bacteria and cells.