Nanodiagnostics as a field makes use of fundamental advances in nanobiotechnology to diagnose, characterize and manage disease at the molecular scale. As these strategies move closer to routine clinical use, a proper understanding of different imaging modalities, relevant biological systems and physical properties governing nanoscale interactions is necessary to rationally engineer next-generation bionanomaterials. In this Review, we analyse the background physics of several clinically relevant imaging modalities and their associated sensitivity and specificity, provide an overview of the materials currently used for in vivo nanodiagnostics, and assess the progress made towards clinical translation. This work provides a framework for understanding both the impressive progress made thus far in the nanodiagnostics field as well as presenting challenges that must be overcome to obtain widespread clinical adoption.

Nanofluidics represents a promising solution to problems in fields ranging from biomolecular analysis to optical property tuning. Recently a number of simple nanofluidic fabrication techniques have been introduced that exploit the deformability of elastomeric materials like polydimethylsiloxane (PDMS). These techniques are limited by the complexity of the devices that can be fabricated, which can only create straight or irregular channels normal to the direction of an applied strain. Here, we report a technique for nanofluidic fabrication based on the controlled collapse of microchannel structures. As is demonstrated, this method converts the easy to control vertical dimension of a PDMS mold to the lateral dimension of a nanochannel. We demonstrate here the creation of complex nanochannel structures as small as 60 nm and provide simple design rules for determining the conditions under which nanochannel formation will occur. The applicability of the technique to biomolecular analysis is demonstrated by showing DNA elongation in a nanochannel and a technique for optofluidic surface enhanced Raman detection of nucleic acids.concentrator ͉ nanofluidic channel ͉ single molecule manipulation ͉ surface enhanced raman scattering O f the many reasons why nanofluidic (1-8) systems are of interest, the most well developed applications revolve around sensing, detection, and species handling in single or ''few'' molecule environments. Researchers have recently demonstrated unique bioanalytical capabilities in nanofluidic devices including the ability to elongate single DNA molecules (2), concentrate protein samples by more than four orders of magnitude (9), and efficiently separate both large (3, 10) and small (4) biomolecules. As a result of their technological promise, numerous methods have been developed to fabricate these systems, including electron beam lithography (11, 12), focused ion beam milling (13), interference lithography (14), AFM lithography (15), and nano-imprint lithography (2, 16). The significant advantages of these high-end nanofabrication technologies are their high resolution, reproducibility, and flexibility. Despite these advantages, these methods are somewhat limited when it comes to rapid prototyping of nanofluidic systems. To augment these high-resolution techniques, several groups have developed simpler nanofluidic fabrication in polydimethylsiloxane (PDMS) using lower resolution lithography methods. Huh et al. (17) for example used crack formation in a surface oxide layer to make nanochannels with mechanically tunable widths. Similarly, Chung et al. (18) used wrinkles on an elastomeric PDMS surface that, when bonded to another surface, formed discrete nanochannels. While these approaches greatly simplify the fabrication of nanochannels, the complexity of the devices that can be created is relatively low, in that only straight lines orthogonal to the stretching force can be fabricated.An additional challenge of nanofluidic fabrication with soft materials like PDMS is the relatively low stiffness ...

SUMMARY Pref-1 is an EGF-repeat containing protein that inhibits adipocyte differentiation. To better understand the origin and development of white adipose tissue (WAT), we generated transgenic mouse models for transient or permanent fluorescent labeling of cells using the Pref-1 promoter, facilitating inducible ablation. We show that Pref-1 marked cells retain proliferative capacity and are very early adipose precursors, prior to expression of Zfp423 or PPAR g. In addition, Pref-1 marked cells establish adipose precursors as mesenchymal, but not endothelial or pericyte in origin. During embryogenesis, Pref-1 marked cells first appear in the dorsal mesenteric region as early as E10.5. These cells become lipid-laden adipocytes at E17.5 in the subcutaneous region, whereas visceral WAT develops after birth. Finally, ablation of Pref-1 marked cells prevents not only embryonic WAT development but also later adult adipose expansion upon high fat feeding, demonstrating the requirement of Pref-1 cells for adipogenesis.

RNA and DNA aptamers that bind to target molecules with high specificity and affinity have been a focus of diagnostics and therapeutic research. These aptamers are obtained by SELEX (Systematic Evolution of Ligands by EXponential enrichment) often requiring more than 10 successive cycles of selection and amplification, where each cycle normally takes 2 days per cycle of SELEX. Here, we have demonstrated the use of sol-gel arrays of proteins in a microfluidic system for efficient selection of RNA aptamers against multiple target molecules. The microfluidic chip incorporates five sol-gel binding droplets, within which specific target proteins are imbedded. The droplets are patterned on top of individually addressable electrical microheaters used for selective elution of aptamers bound to target proteins in the sol-gel droplets. We demonstrate that specific aptamers bind their respective protein targets and can be selectively eluted by micro-heating. Finally, our microfluidic SELEX system greatly improved selection efficiency, reducing the number of selection cycles needed to produce high affinity aptamers. The process is readily scalable to larger arrays of sol-gel-embedded proteins. To our knowledge, this is the first demonstration of a chip-based selection of aptamers using microfluidics, thereby allowing development of a high throughput and efficient SELEX procedures.

Endogenous biomarkers remain at the forefront of early disease detection efforts, but many lack the sensitivities and specificities necessary to influence disease management. Inspired by emerging adoptive cell transfer immunotherapies and the natural migration of immune cells to pathology, here we describe a new class of cell-based in vivo sensors for ultrasensitive disease detection. In our proof of concept, we perform adoptive transfer of syngeneic macrophages which were engineered to produce a synthetic biomarker upon adopting a 'tumor-associated' metabolic profile. Notably, the macrophage sensor detected tumors as small as 25-50 mm 3 , effectively tracked the immunological response in two models of acute inflammation, and was more sensitive than both protein and nucleic acid cancer biomarkers. This technology establishes a clinically translatable approach to early cancer detection and provides a conceptual framework for the use of engineered immune cells for the monitoring of many disease states in addition to cancer.

Circulating tumor cells (CTCs) are established cancer biomarkers for the “liquid biopsy” of tumors. Molecular analysis of single CTCs, which recapitulate primary and metastatic tumor biology, remains challenging because current platforms have limited throughput, are expensive, and are not easily translatable to the clinic. Here, we report a massively parallel, multigene-profiling nanoplatform to compartmentalize and analyze hundreds of single CTCs. After high-efficiency magnetic collection of CTC from blood, a single-cell nanowell array performs CTC mutation profiling using modular gene panels. Using this approach, we demonstrated multigene expression profiling of individual CTCs from non–small-cell lung cancer (NSCLC) patients with remarkable sensitivity. Thus, we report a high-throughput, multiplexed strategy for single-cell mutation profiling of individual lung cancer CTCs toward minimally invasive cancer therapy prediction and disease monitoring.

Technologies for the longitudinal monitoring of a person's health are poorly integrated with clinical workflows, and have rarely produced actionable biometric data for healthcare providers. Here, we describe easily deployable hardware and software for the long-term analysis of a user's excreta through data collection and models of human health. The 'smart' toilet, which is selfcontained and operates autonomously by leveraging pressure and motion sensors, analyses the user's urine using a standard-of-care colorimetric assay that traces red-green-blue values from images of urinalysis strips, calculates the flow rate and volume of urine using computer vision as a uroflowmeter, and classifies stool according to the Bristol stool form scale using deep learning, with performance that is comparable to the performance of trained medical personnel. Each user of the toilet is identified through their fingerprint and the distinctive features of their anoderm, and the data are securely stored and analysed in an encrypted cloud server. The toilet may find uses in the screening, diagnosis and longitudinal monitoring of specific patient populations.

The detection and analysis of rare blood biomarkers is necessary for early diagnosis of cancer and to facilitate the development of tailored therapies. However, current methods for the isolation of circulating tumour cells (CTCs) or nucleic acids present in a standard clinical sample of only 5–10 ml of blood provide inadequate yields for early cancer detection and comprehensive molecular profiling. Here, we report the development of a flexible magnetic wire that can retrieve rare biomarkers from the subject’s blood in vivo at a much higher yield. The wire is inserted and removed through a standard intravenous catheter and captures biomarkers that have been previously labelled with injected magnetic particles. In a proof-of-concept experiment in a live porcine model, we demonstrate the in vivo labelling and single-pass capture of viable model CTCs in less than 10 s. The wire achieves capture efficiencies that correspond to enrichments of 10–80 times the amount of CTCs in a 5-ml blood draw, and 500–5,000 times the enrichments achieved using the commercially available Gilupi CellCollector.