Nanotechnologies for biomedical science and translational medicine

Abstract

In 2000 the United States launched the National Nanotechnology Initiative and, along with it, a well-defined set of goals for nanomedicine. This Perspective looks back at the progress made toward those goals, within the context of the changing landscape in biomedicine that has occurred over the past 15 years, and considers advances that are likely to occur during the next decade. In particular, nanotechnologies for health-related genomics and single-cell biology, inorganic and organic nanoparticles for biomedicine, and wearable nanotechnologies for wellness monitoring are briefly covered.

Keywords: biotechnology; nanomedicine; nanotechnology.

Fig. 1.

Nanotechnologies for genome mapping and genome sequencing. (A) Nanochannel-based genome mapping. (i) The microchip is designed to untangle the DNA and guide long fragments into nanochannels with diameters <100 nm. (ii) The DNA fragments are fluorescently labeled at specific sites to provide a spatial map of those sites. (iii) Different fragments are lined up according to the spatially resolved fluorescent signatures to provide the genome map, shown here for a 300-kb segment. Adapted from ref. , with permission from Macmillan Publishers Ltd: Nature Biotechnology, copyright 2012. (B) The Pacific Biosciences nanopore-based genome-sequencing platform, in which single-molecule, real-time sequencing data are obtained from a DNA polymerase that is isolated within a 100-nm-diameter pore in an aluminum film. (i) The pore serves as a zero mode waveguide for optical analysis of uninterrupted template-directed DNA synthesis using four distinguishable fluorescently labeled dNTPs. (ii) The temporal order of enzymatic incorporation of the dNTPs into a growing DNA strand is illustrated. At each step a fluorescent dNTP is incorporated, generating a fluorescent signal that is collected efficiently within the nanowaveguide. The fluorophore then is cleaved and diffuses out of the waveguide. (iii) An optical readout for a single channel is illustrated. Reproduced from ref. , with permission from AAAS.

Fig. 2.

Microfluidics and nanotech tools for single-cell analysis. (A) Illustration of a single-cell barcode chip (SCBC) in which individual cells are isolated within nanoliter or smaller volume microchambers within a microfluidics chip mounted on a microscope slide. The glass slide is patterned with a high-density barcode for protein and/or metabolite assays from isolated single cells. Cells are lysed using the valved microchamber structure shown in the middle drawing, and the contents are captured on specific locations within the barcode array. The fluorescence intensities of the developed barcode stripes are related to calibration curves to yield the level of the specific analytes. (B) Sample of single-cell data taken on an SCBC. (i) The scatter plot shows the correlated levels of two phosphoproteins as measured from single cells (red dots) or zero-cell chambers (blue dots). (ii) A protein–protein correlation matrix from a multiplex SCBC protein and metabolite assay. Adapted from ref. . (C) An illustration of a microfluidics platform for building a regular array of single cells within nanoliter droplets of water, entrained in oil. The optical micrograph is reproduced from ref. , with permission from The Royal Society of Chemistry. The drawing illustrates some of the flexible design parameters that are used in this type of high-throughput assay. Cells can be probed with antibodies, viruses, mRNA-encoded beads, NPs, and so forth for a controllable amount of time, using a delay line or related method. Cells may be interrogated optically and sorted or otherwise analyzed at the protein, transcript, or functional level.

Fig. 3.

The gold NP-based nanoflare construct is used for detecting specific mRNAs in live cells. The gold NPs are coated with a dense layer of DNA, which promotes cell penetration. The DNA shown comprises a fluorescent reporter (the Cy5 flare), which is nonfluorescent when bound to the Au NP. This nanoflare is hybridized with an antisense DNA. When the nanoflare encounters the target mRNA, the flare is released, thus activating fluorescence within the cell and permitting live-cell sorting based on the expression of a specific gene. Adapted from ref. .

Fig. 4.

Semiconductor QD and SWNT in vivo imaging probes. (A) Semiconductor QD imaging of stem cells in bone marrow. (i) Polyimidazole incorporating norbornene provides a bio-compatible surface functionalization for highly luminescent semiconductor core-shell QDs as well as a chemical handle for preparing QD–antibody conjugates, as shown (not to scale). Lyscine (amine-presenting) residues on the antibody are highlighted in red. The QD–antibody particles exhibit a moderate negative surface charge, which is generally favorable for improved in vivo circulation. (ii) Use of the QD–antibody particles as in vivo imaging probes for single-cell imaging in the bone marrow of a live murine model, viewed through a calvarial window. The arrow points to single Sca-1⁺c-Kit⁺ cell, which is a late-stage hematopoietic stem cell. The red and green cells represent Sca-1⁺ and c-Kit⁺ cells, respectively. Adapted from ref. . (B) Polymer-stabilized SWNTs used as in vivo near-infrared (NIR) fluorescent probes of vasculature. (i) Near-IR fluorescence of mouse vasculature. (ii) Fluorescence intensity taken along the dashed green line drawn on the image in i is plotted and reveals an imaging resolution of a few tens of micrometers. Adapted from ref. , with permission from Macmillan Publishers Ltd: Nature Medicine, copyright 2012.

Fig. 5.

Illustration of the PRINT method for making nano- and microparticles. (A) PRINT uses the micro- and nanolithography fabrication tools of the semiconductor industry to build molds (shown in green). These are coupled with roll-to-roll processing to prepare size- and shape-controlled particles that then are released from the molds. Different polymer and hydrogel chemistries are used to control the chemical and physical properties of those particles. (B and C) Two batches of fluorescent hydrogel microparticles are prepared with different elastic moduli, based on the extent of cross-linking (10% in B; 1% in C). The particles with the lowest cross-linking have elastic moduli designed to emulate that of a red blood cell. (D) Illustration of the organ distribution of the PRINT particles with high and low numbers of elastic moduli 2 h after tail injection into a mouse. Adapted from ref. . The particles illustrated here are being investigated, in a preclinical setting, as a component of synthetic blood.

Fig. 6.

A polymer-based 70-nm nanotherapeutic for siRNA delivery in humans. (A) Cyclodextran (CD) forms a conical binding pocket for the supramolecular assembly of adamantane (AD). A poly-CD oligomer has several such binding pockets, which can be used for the assembly of adamantane-labeled drugs or, in the example shown, TF ligands that can target cancer cells. When poly-CD is combined with adamantane-labeled TF and siRNA, the TF is presented on the surface of the NP, and the siRNA is localized within the hydrophilic interior, thus providing directed delivery of the siRNA to cancer cells. The nanotherapeutic is administered to patients intravenously. (B) Data from a clinical trial on melanoma cancer patients. Five-nanometer adamantane-labeled gold NPs (Au-PEG-AD) are used for tissue labeling of the poly-CD NPs. The three images show that the NPs (green color in left image) are not in the skin (s) or the epidermis (epi) but instead are localized within the tumor (t). Adapted from ref. , with permission from Macmillan Publishers Ltd, Nature, copyright 2012. Related poly-CD nanotherapeutics are being tested in several clinical trials for various cancer indications.

Fig. 7.

Graphene nanotechnology integrated into flexible electronics yields a potentially wearable sensor platform. (A) Graphene is printed onto bioresorbable silk and then is electrically contacted with a small electrical circuit before transfer onto the surface of a tooth. The flexible circuit consists of interdigitated capacitive electrodes (to sense the graphene electrical conductivity) and a planar meander line inductor. The graphene is chemically modified with a bifunctional peptide to bind to the graphene and to exhibit affinity for specific bacteria. Exposure to bacteria modulates the electrical conductivity of the graphene, which is measured by the interdigitating electrodes and is transmitted wirelessly to an inductively coupled receiver. (B) Benchtop experiments show the ability of this sensor system to detect a specific biological agent (Helicobacter pylori) (Left) and a periodic physiological process (breathing) (Right). Adapted from ref. , with permission from Macmillan Publishers Ltd: Nature Communications, copyright 2012.