Metabolomics based markers predict type 2 diabetes in a 14-year follow-up study

Chemical probes are key components of the bioimaging toolbox, as they label biomolecules in cells and tissues. The new challenge in bioimaging is to design chemical probes for three-dimensional (3D) tissue imaging. In this work, we discovered that light scattering of metal nanoparticles can provide 3D imaging contrast in intact and transparent tissues. The nanoparticles can act as a template for the chemical growth of a metal layer to further enhance the scattering signal. The use of chemically grown nanoparticles in whole tissues can amplify the scattering to produce a 1.4 million-fold greater photon yield than obtained using common fluorophores. These probes are non-photobleaching and can be used alongside fluorophores without interference. We demonstrated three distinct biomedical applications: (a) molecular imaging of blood vessels, (b) tracking of nanodrug carriers in tumors, and (c) mapping of lesions and immune cells in a multiple sclerosis mouse model. Our strategy establishes a distinct yet complementary set of imaging probes for understanding disease mechanisms in three dimensions

Engineering the Structure and Properties of DNA-Nanoparticle Superstructures Using Polyvalent Counterions

DNA assembly of nanoparticles is a powerful approach to control their properties and prototype new materials. However, the structure and properties of DNA-assembled nanoparticles are labile and sensitive to interactions with counterions, which vary with processing and application environment. Here we show that substituting polyamines in place of elemental counterions significantly enhanced the structural rigidity and plasmonic properties of DNA-assembled metal nanoparticles. These effects arose from the ability of polyamines to condense DNA and cross-link DNA-coated nanoparticles. We further used polyamine wrapped DNA nanostructures as structural templates to seed the growth of polymer multilayers via layer-by-layer assembly, and controlled the degree of DNA condensation, plasmon coupling efficiency, and material responsiveness to environmental stimuli by varying polyelectrolyte composition. These results highlight counterion engineering as a versatile strategy to tailor the properties of DNA-nanoparticle assemblies for various applications, and should be applicable to other classes of DNA nanostructures

Automating Quantum Dot Barcode Assays Using Microfluidics and Magnetism for the Development of a Point-of-Care Device

The impact of detecting multiple infectious diseases simultaneously at point-of-care with good sensitivity, specificity, and reproducibility would be enormous for containing the spread of diseases in both resource-limited and rich countries. Many barcoding technologies have been introduced for addressing this need as barcodes can be applied to detecting thousands of genetic and protein biomarkers simultaneously. However, the assay process is not automated and is tedious and requires skilled technicians. Barcoding technology is currently limited to use in resource-rich settings. Here we used magnetism and microfluidics technology to automate the multiple steps in a quantum dot barcode assay. The quantum dot-barcoded microbeads are sequentially (a) introduced into the chip, (b) magnetically moved to a stream containing target molecules, (c) moved back to the original stream containing secondary probes, (d) washed, and (e) finally aligned for detection. The assay requires 20 min, has a limit of detection of 1.2 nM, and can detect genetic targets for HIV, hepatitis B, and syphilis. This study provides a simple strategy to automate the entire barcode assay process and moves barcoding technologies one step closer to point-of-care applications

Simplifying Assays by Tableting Reagents

Medical diagnostic assays provide exquisite sensitivity and precision in the diagnoses of patients. However, these technologies often require multiple steps, skilled technicians, and facilities to store heat-sensitive reagents. Here, we developed a high-throughput compression method to incorporate different assay components into color-coded tablets. With our technique, premeasured quantities of reagents can be encapsulated in compressed tablets. We show that tableting stabilizes heat-sensitive reagents and simplifies a broad range of assays, including isothermal nucleic acid amplification techniques, enzyme-based immunoassays, and microbead diagnostics. To test the clinical readiness of this tableting technology, we show the ability of tableted diagnostics for screening hepatitis B-positive patient samples. Our development simplifies complicated assays and the transportation of reagents and mitigates the need for refrigeration of reagents. This advances the use of complex assays in remote areas with limited infrastructure

Exploring Passive Clearing for 3D Optical Imaging of Nanoparticles in Intact Tissues

The three-dimensional (3D) optical imaging of nanoparticle distribution within cells and tissues can provide insights into barriers to nanoparticle transport in vivo. However, this approach requires the preparation of optically transparent samples using harsh chemical and physical methods, which can lead to a significant loss of nanoparticles and decreased sensitivity of subsequent analyses. Here, we investigate the influence of electrophoresis and clearing time on nanoparticle retention within intact tissues and the impact of these factors on the final 3D image quality. Our findings reveal that longer clearing times lead to a loss of nanoparticles but improved transparency of tissues. We discovered that passive clearing improved nanoparticle retention 2-fold compared to results from electrophoretic clearing. Using the passive clearing approach, we were able to observe a small population of nanoparticles undergoing hepatobiliary clearance, which could not be observed in liver tissues that were prepared by electrophoretic clearing. This strategy enables researchers to visualize the interface between nanomaterials and their surrounding biological environment with high sensitivity, which enables quantitative and unbiased analysis for guiding the next generation of nanomedicine designs

Clinical Validation of Quantum Dot Barcode Diagnostic Technology

There has been a major focus on the clinical translation of emerging technologies for diagnosing patients with infectious diseases, cancer, heart disease, and diabetes. However, most developments still remain at the academic stage where researchers use spiked target molecules to demonstrate the utility of a technology and assess the analytical performance. This approach does not account for the biological complexities and variabilities of human patient samples. As a technology matures and potentially becomes clinically viable, one important intermediate step in the translation process is to conduct a full clinical validation of the technology using a large number of patient samples. Here, we present a full detailed clinical validation of Quantum Dot (QD) barcode technology for diagnosing patients infected with Hepatitis B Virus (HBV). We further demonstrate that the detection of multiple regions of the viral genome using multiplexed QD barcodes improved clinical sensitivity from 54.9–66.7% to 80.4–90.5%, and describe how to use QD barcodes for optimal clinical diagnosis of patients. The use of QDs in biology and medicine was first introduced in 1998 but has not reached clinical care. This study describes our long-term systematic development strategy to advance QD technology to a clinically feasible product for diagnosing patients. Our “blueprint” for translating the QD barcode research concept could be adapted for other nanotechnologies, to efficiently advance diagnostic techniques discovered in the academic laboratory to patient care

Nanoparticle Size and Surface Chemistry Determine Serum Protein Adsorption and Macrophage Uptake

Delivery and toxicity are critical issues facing nanomedicine research. Currently, there is limited understanding and connection between the physicochemical properties of a nanomaterial and its interactions with a physiological system. As a result, it remains unclear how to optimally synthesize and chemically modify nanomaterials for <i>in vivo</i> applications. It has been suggested that the physicochemical properties of a nanomaterial after synthesis, known as its “synthetic identity”, are not what a cell encounters <i>in vivo</i>. Adsorption of blood components and interactions with phagocytes can modify the size, aggregation state, and interfacial composition of a nanomaterial, giving it a distinct “biological identity”. Here, we investigate the role of size and surface chemistry in mediating serum protein adsorption to gold nanoparticles and their subsequent uptake by macrophages. Using label-free liquid chromatography tandem mass spectrometry, we find that over 70 different serum proteins are heterogeneously adsorbed to the surface of gold nanoparticles. The relative density of each of these adsorbed proteins depends on nanoparticle size and poly­(ethylene glycol) grafting density. Variations in serum protein adsorption correlate with differences in the mechanism and efficiency of nanoparticle uptake by a macrophage cell line. Macrophages contribute to the poor efficiency of nanomaterial delivery into diseased tissues, redistribution of nanomaterials within the body, and potential toxicity. This study establishes principles for the rational design of clinically useful nanomaterials

Secreted Biomolecules Alter the Biological Identity and Cellular Interactions of Nanoparticles

A nanoparticle’s physical and chemical properties at the time of cell contact will determine the ensuing cellular response. Aggregation and the formation of a protein corona in the extracellular environment will alter nanoparticle size, shape, and surface properties, giving it a “biological identity” that is distinct from its initial “synthetic identity”. The biological identity of a nanoparticle depends on the composition of the surrounding biological environment and determines subsequent cellular interactions. When studying nanoparticle–cell interactions, previous studies have ignored the dynamic composition of the extracellular environment as cells deplete and secrete biomolecules in a process known as “conditioning”. Here, we show that cell conditioning induces gold nanoparticle aggregation and changes the protein corona composition in a manner that depends on nanoparticle diameter, surface chemistry, and cell phenotype. The evolution of the biological identity in conditioned media enhances the cell membrane affinity, uptake, and retention of nanoparticles. These results show that dynamic extracellular environments can alter nanoparticle–cell interactions by modulating the biological identity. The effect of the dynamic nature of biological environments on the biological identity of nanoparticles must be considered to fully understand nano–bio interactions and prevent data misinterpretation

Three-Dimensional Imaging of Transparent Tissues via Metal Nanoparticle Labeling

Chemical probes are key components of the bioimaging toolbox, as they label biomolecules in cells and tissues. The new challenge in bioimaging is to design chemical probes for three-dimensional (3D) tissue imaging. In this work, we discovered that light scattering of metal nanoparticles can provide 3D imaging contrast in intact and transparent tissues. The nanoparticles can act as a template for the chemical growth of a metal layer to further enhance the scattering signal. The use of chemically grown nanoparticles in whole tissues can amplify the scattering to produce a 1.4 million-fold greater photon yield than obtained using common fluorophores. These probes are non-photobleaching and can be used alongside fluorophores without interference. We demonstrated three distinct biomedical applications: (a) molecular imaging of blood vessels, (b) tracking of nanodrug carriers in tumors, and (c) mapping of lesions and immune cells in a multiple sclerosis mouse model. Our strategy establishes a distinct yet complementary set of imaging probes for understanding disease mechanisms in three dimensions

Three-Dimensional Imaging of Transparent Tissues via Metal Nanoparticle Labeling

Chemical probes are key components of the bioimaging toolbox, as they label biomolecules in cells and tissues. The new challenge in bioimaging is to design chemical probes for three-dimensional (3D) tissue imaging. In this work, we discovered that light scattering of metal nanoparticles can provide 3D imaging contrast in intact and transparent tissues. The nanoparticles can act as a template for the chemical growth of a metal layer to further enhance the scattering signal. The use of chemically grown nanoparticles in whole tissues can amplify the scattering to produce a 1.4 million-fold greater photon yield than obtained using common fluorophores. These probes are non-photobleaching and can be used alongside fluorophores without interference. We demonstrated three distinct biomedical applications: (a) molecular imaging of blood vessels, (b) tracking of nanodrug carriers in tumors, and (c) mapping of lesions and immune cells in a multiple sclerosis mouse model. Our strategy establishes a distinct yet complementary set of imaging probes for understanding disease mechanisms in three dimensions