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The successful delivery of nanoparticles to solid tumors depends on their ability to pass through blood vessels and into the tumor microenvironment. Here, we discovered a subset of tumor endothelial cells that facilitate nanoparticle transport into solid tumors. We named these cells nanoparticle transport endothelial cells (N-TECs). We show that only 21% of tumor endothelial cells located on a small number of vessels are involved in transporting nanoparticles into the tumor microenvironment. N-TECs have an increased expression of genes related to nanoparticle transport and vessel permeability compared to other tumor endothelial cells. The N-TECs act as gatekeepers that determine the entry point, distribution, cell accessibility, and number of nanoparticles that enter the tumor microenvironment.

Nanoparticle delivery to solid tumours over the past ten years has stagnated at a median of 0.7% of the injected dose. Varying nanoparticle designs and strategies have yielded only minor improvements. Here we discovered a dose threshold for improving nanoparticle tumour delivery: 1 trillion nanoparticles in mice. Doses above this threshold overwhelmed Kupffer cell uptake rates, nonlinearly decreased liver clearance, prolonged circulation and increased nanoparticle tumour delivery. This enabled up to 12% tumour delivery efficiency and delivery to 93% of cells in tumours, and also improved the therapeutic efficacy of Caelyx/Doxil. This threshold was robust across different nanoparticle types, tumour models and studies across ten years of the literature. Our results have implications for human translation and highlight a simple, but powerful, principle for designing nanoparticle cancer treatments. Efficient nanoparticle delivery into tumours has been a challenge in the field. It is now shown that the efficiency can be improved substantially when the dose breaches a specific threshold.

Current urinary tract infection (UTI) diagnostic methods are slow or provide limited information, resulting in prescribing antibiotic therapy before bacterial pathogen identification. Here, we adapted a gold nanoparticle colorimetric approach and developed a smartphone platform for UTI detection. We show the parallel identification of five major UTI pathogens at clinically relevant concentrations of 10

The surface of nanoparticles changes immediately after intravenous injection because blood proteins adsorb on the surface. How this interface changes during circulation and its impact on nanoparticle distribution within the body is not understood. Here, we developed a workflow to show that the evolution of proteins on nanoparticle surfaces predicts the biological fate of nanoparticles in vivo. This workflow involves extracting nanoparticles at multiple time points from circulation, isolating the proteins off the surface and performing proteomic mass spectrometry. The mass spectrometry protein library served as inputs, while blood clearance and organ accumulation were used as outputs to train a supervised deep neural network that predicts nanoparticle biological fate. In a double-blinded study, we tested the network by predicting nanoparticle spleen and liver accumulation with upward of 94% accuracy. Our neural network discovered that the mechanism of liver and spleen uptake is due to patterns of a multitude of nanoparticle surface adsorbed proteins. There are too many combinations to change these proteins manually using chemical or biological inhibitors to alter clearance. Therefore, we developed a technique that uses the host to act as a bioreactor to prepare nanoparticles with predictable clearance patterns that reduce liver and spleen uptake by 50% and 70%, respectively. These techniques provide opportunities to both predict nanoparticle behavior and also to engineer surface chemistries that are specifically designed by the body.

Limited tumor nanoparticle accumulation remains one of the main challenges in cancer nanomedicine. Here, we demonstrate that subtherapeutic photodynamic priming (PDP) enhances the accumulation of nanoparticles in subcutaneous murine prostate tumors ∼3-5-times without inducing cell death, vascular destruction, or tumor growth delay. We also found that PDP resulted in an ∼2-times decrease in tumor collagen content as well as a significant reduction of extracellular matrix density in the subendothelial zone. Enhanced nanoparticle accumulation combined with the reduced extravascular barriers improved therapeutic efficacy in the absence of off-target toxicity, wherein 5 mg/kg of Doxil with PDP was equally effective in delaying tumor growth as 15 mg/kg of Doxil. Overall, this study demonstrates the potential of PDP to enhance tumor nanomedicine accumulation and alleviate tumor desmoplasia without causing cell death or vascular destruction, highlighting the utility of PDP as a minimally invasive priming strategy that can improve therapeutic outcomes in desmoplastic tumors.

Coating the nanoparticle surface with cancer cell recognizing ligands is expected to facilitate specific delivery of nanoparticles to diseased cells in vivo. While this targeting strategy is appealing, no nanoparticle-based active targeting formulation for solid tumor treatment had made it past phase III clinical trials. Here, we quantified the cancer cell-targeting efficiencies of Trastuzumab (Herceptin) and folic acid coated gold and silica nanoparticles in multiple mouse tumor models. Surprisingly, we showed that less than 14 out of 1 million (0.0014% injected dose) intravenously administrated nanoparticles were delivered to targeted cancer cells, and that only 2 out of 100 cancer cells interacted with the nanoparticles. The majority of the intratumoral nanoparticles were either trapped in the extracellular matrix or taken up by perivascular tumor associated macrophages. The low cancer cell targeting efficiency and significant uptake by noncancer cells suggest the need to re-evaluate the active targeting process and therapeutic mechanisms using quantitative methods. This will be important for developing strategies to deliver emerging therapeutics such as genome editing, nucleic acid therapy, and immunotherapy for cancer treatment using nanocarriers.

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 (3D) optical microscopy can be used to understand and improve the delivery of nanomedicine. However, this approach cannot be performed for analyzing liposomes in tissues because the processing step to make tissues transparent for imaging typically removes the lipids. Here, we developed a tag, termed REMNANT, that enables 3D imaging of organic materials in biological tissues. We demonstrated the utility of this tag for the 3D mapping of liposomes in intact tissues. We also showed that the tag is able to monitor the release of entrapped therapeutic agents. We found that liposomes release their cargo >100-fold faster in tissues in vivo than in conventional in vitro assays. This allowed us to design a liposomal formulation with enhanced ability to kill tumor associated macrophages. Our development opens up new opportunities for studying the chemical properties and pharmacodynamics of administered organic materials in an intact biological environment. This approach provides insight into the in vivo behavior of degradable materials, where the newly discovered information can guide the engineering of the next generation of imaging and therapeutic agents.

Mobile phone technology is a perfect companion for point-of-care diagnostics as they come equipped with advanced processors, high resolution cameras, and network connectivity. Despite several academic pursuits, only a few mobile phone diagnostics have been tested in the field, commercialized or achieved regulatory approval. This review will address the challenges associated with developing mobile diagnostics and suggest strategies to overcome them. We aim to provide a resource for researchers to accelerate the development of new diagnostics. Our Account includes an overview of published mobile phone diagnostics and highlights lessons learned from their approach to diagnostic development. Also, we have included recommendations from regulatory and public health agencies, such as the U.S. Food and Drug Administration and World Health Organization, to further guide researchers. We believe that the development of mobile phone point-of-care diagnostics takes place in four distinct steps: (1) Needs and Value Assessment, (2) Technology Development, (3) Preclinical Verification, and (4) Clinical Validation and Field Trials. During each step, we outline developmental strategies to help researchers avoid potential challenges. (1) Researchers commonly develop devices to maximize technical parameters such as sensitivity and time which do not necessarily translate to increased clinical impact. Researchers must focus on assessing specific diagnostic needs and the value which a potential device would offer. (2) Often, researchers claim they have developed devices for feasible implementation at the point-of-care, yet they rely on laboratory resources. Researchers must develop equipment-free devices which are agnostic to any mobile phone. (3) Another challenge researchers face is decreased performance during field evaluations relative to initial laboratory verification. Researchers must ensure that they simulate the field conditions during laboratory verification to achieve successful translation. (4) Finally, proper field testing of devices must be performed in conditions which match that of the final intended use. The future of mobile phone point-of-care diagnostic devices is bright and has the potential to radically change how patients are diagnosed. Before we reach this point, researchers must take a step backward and focus on the first-principles of basic research. The widespread adoption and rapid scaling of these devices can only be achieved once the fundamentals have been considered. The insights and strategies provided here will help researchers avoid pitfalls, streamline development and make better decisions during the development of new diagnostics. Further, we believe this Account can help push the field of mobile diagnostics toward increased productivity, leading to more approved devices and ultimately helping curb the burden of disease worldwide.

Metastasis of solid tumors is a key determinant of cancer patient survival. Targeting micrometastases using nanoparticles could offer a way to stop metastatic tumor growth before it causes excessive patient morbidity. However, nanoparticle delivery to micrometastases is difficult to investigate because micrometastases are small in size and lie deep within tissues. Here, we developed an imaging and image analysis workflow to analyze nanoparticle–cell interactions in metastatic tumors. This technique combines tissue clearing and 3D microscopy with machine learning-based image analysis to assess the physiology of micrometastases with single-cell resolution and quantify the delivery of nanoparticles within them. We show that nanoparticles access a higher proportion of cells in micrometastases (50% nanoparticle-positive cells) compared with primary tumors (17% nanoparticle-positive cells) because they reside close to blood vessels and require a small diffusion distance to reach all tumor cells. Furthermore, the high-throughput nature of our image analysis workflow allowed us to profile the physiology and nanoparticle delivery of 1,301 micrometastases. This enabled us to use machine learning-based modeling to predict nanoparticle delivery to individual micrometastases based on their physiology. Our imaging method allows researchers to measure nanoparticle delivery to micrometastases and highlights an opportunity to target micrometastases with nanoparticles. The development of models to predict nanoparticle delivery based on micrometastasis physiology could enable personalized treatments based on the specific physiology of a patient’s micrometastases.

The surface of nanoparticles changes immediately after intravenous injection because blood proteins adsorb on the surface. How this interface changes during circulation and its impact on nanoparticle distribution within the body is not understood. Here, we developed a workflow to show that the evolution of proteins on nanoparticle surfaces predicts the biological fate of nanoparticles

The concept of nanoparticle transport through gaps between endothelial cells (inter-endothelial gaps) in the tumour blood vessel is a central paradigm in cancer nanomedicine. The size of these gaps was found to be up to 2,000 nm. This justified the development of nanoparticles to treat solid tumours as their size is small enough to extravasate and access the tumour microenvironment. Here we show that these inter-endothelial gaps are not responsible for the transport of nanoparticles into solid tumours. Instead, we found that up to 97% of nanoparticles enter tumours using an active process through endothelial cells. This result is derived from analysis of four different mouse models, three different types of human tumours, mathematical simulation and modelling, and two different types of imaging techniques. These results challenge our current rationale for developing cancer nanomedicine and suggest that understanding these active pathways will unlock strategies to enhance tumour accumulation. The dominant mechanism of nanoparticle entry into solid tumours has now been shown to be an active trans-endothelial pathway rather than the currently established passive transport via inter-endothelial gaps.

On-chip imaging of intact three-dimensional tissues within microfluidic devices is fundamentally hindered by intratissue optical scattering, which impedes their use as tissue models for high-throughput screening assays. Here, we engineered a microfluidic system that preserves and converts tissues into optically transparent structures in less than 1 d, which is 20× faster than current passive clearing approaches. Accelerated clearing was achieved because the microfluidic system enhanced the exchange of interstitial fluids by 567-fold, which increased the rate of removal of optically scattering lipid molecules from the cross-linked tissue. Our enhanced clearing process allowed us to fluorescently image and map the segregation and compartmentalization of different cells during the formation of tumor spheroids, and to track the degradation of vasculature over time within extracted murine pancreatic islets in static culture, which may have implications on the efficacy of beta-cell transplantation treatments for type 1 diabetes. We further developed an image analysis algorithm that automates the analysis of the vasculature connectivity, volume, and cellular spatial distribution of the intact tissue. Our technique allows whole tissue analysis in microfluidic systems, and has implications in the development of organ-on-a-chip systems, high-throughput drug screening devices, and in regenerative medicine.

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.

Nanoparticles are commonly administered through systemic injection, which exposes them to the dynamic environment of the bloodstream. Injected nanoparticles travel within the blood and experience a wide range of flow velocities that induce varying shear rates to the blood vessels. Endothelial cells line these vessels, and have been shown to uptake nanoparticles during circulation, but it is difficult to characterize the flow-dependence of this interaction in vivo. Here, a microfluidic system is developed to control the flow rates of nanoparticles as they interact with endothelial cells. Gold nanoparticle uptake into endothelial cells is quantified at varying flow rates, and it is found that increased flow rates lead to decreased nanoparticle uptake. Endothelial cells respond to increased flow shear with decreased ability to uptake the nanoparticles. If cells are sheared the same way, nanoparticle uptake decreases as their flow velocity increases. Modifying nanoparticle surfaces with endothelial-cell-binding ligands partially restores uptake to nonflow levels, suggesting that functionalizing nanoparticles to bind to endothelial cells enables nanoparticles to resist flow effects. In the future, this microfluidic system can be used to test other nanoparticle-endothelial cell interactions under flow. The results of these studies can guide the engineering of nanoparticles for in vivo medical applications.

The role of tissue architecture in mediating nanoparticle transport, targeting, and biological effects is unknown due to the lack of tools for imaging nanomaterials in whole organs. Here, we developed a rapid optical mapping technique to image nanomaterials in intact organs ex vivo and in three-dimensions (3D). We engineered a high-throughput electrophoretic flow device to simultaneously transform up to 48 tissues into optically transparent structures, allowing subcellular imaging of nanomaterials more than 1 mm deep into tissues which is 25-fold greater than current techniques. A key finding is that nanomaterials can be retained in the processed tissue by chemical cross-linking of surface adsorbed serum proteins to the tissue matrix, which enables nanomaterials to be imaged with respect to cells, blood vessels, and other structures. We developed a computational algorithm to analyze and quantitatively map nanomaterial distribution. This method can be universally applied to visualize the distribution and interactions of materials in whole tissues and animals including such applications as the imaging of nanomaterials, tissue engineered constructs, and biosensors within their intact biological environment.

Local delivery of drugs offers the potential for high local drug concentration while minimizing systemic toxicity, which is often observed with oral dosing. However, local depots are typically administered less frequently and include an initial burst followed by a continuous release. To maximize efficiency of therapy, it is critical to ensure that drug is only released when needed. One of the hallmarks of rheumatoid arthritis, for example, is its variable disease activity consisting of exacerbations of inflammation punctuated by periods of remission. This presents significant challenges for matching localized drug delivery with disease activity. An optimal system would be nontoxic and only release drugs during the period of exacerbation, self-titrating in response to the level of inflammation. We report the development of an injectable self-assembled nanofibrous hydrogel, from a generally recognized as safe material, which is capable of encapsulation and release of agents in response to specific enzymes that are significantly upregulated in a diseased state including matrix metalloproteinases (MMP-2 and MMP-9) and esterases. We show that these self-assembled nanofibrous gels can withstand shear forces that may be experienced in dynamic environments such as joints, can remain stable following injection into healthy joints of mice, and can disassemble in vitro to release encapsulated agents in response to synovial fluid from arthritic patients. This novel approach represents a next-generation therapeutic strategy for localized treatment of proteolytic diseases.

This paper presents a novel MOEMS (Micro Opto Electromechanical Systems) pressure sensor suitable for localized precision measurements in high temperature environments. The sensor is based on a micromachined Fabry-Perot device (MFPD) that uses a thin film microcantilever beam as the top mirror and a silicon substrate as the bottom mirror of the optical microcavity. The major effect that the viscosity and density of the air surrounding the MFPD have on the viscous damping provides the mechanism for the detection of the pressure. A major advantage of this configuration is that there is no need for a sealed microcavity since the air is trapped by the viscous damping effects. The sensor has been tested up to 90 psi and pressure sensitivities of about 0·04%/psi with a MFPD sensor with a resonant frequency of about 46·7 kHz have been measured.

Inorganic nanoparticles are ideal precursors for engineering barcodes for rapidly detecting diseases. Despite advances in the chemical design of these barcodes, they have not advanced to clinical use because they lack sensitivity and are not cost-effective due to requirement of a large read-out system. Here we combined recent advances in quantum dot barcode technology with smartphones and isothermal amplification to engineer a simple and low-cost chip-based wireless multiplex diagnostic device. We characterized the analytical performance of this device and demonstrated that the device is capable of detecting down to 1000 viral genetic copies per milliliter, and this enabled the diagnosis of patients infected with HIV or hepatitis B. More importantly, the barcoding enabled us to detect multiple infectious pathogens simultaneously, in a single test, in less than 1 h. This multiplexing capability of the device enables the diagnosis of infections that are difficult to differentiate clinically due to common symptoms such as a fever or rash. The integration of quantum dot barcoding technology with a smartphone reader provides a capacity for global surveillance of infectious diseases and the potential to accelerate knowledge exchange transfer of emerging or exigent disease threats with healthcare and military organizations in real time.

There are currently no nanoparticle formulations that optimally target diseased cells in the body. A small percentage of nanoparticles reach these cells and most accumulate in cells of the mononuclear phagocytic system. This chapter explores the interactions between nanoparticles and cells that may explain the causes for off-target accumulation of nanoparticles. A greater understanding of the nanoparticle-cellular interactions will lead to improvements in particle design for improved therapeutic outcome.

The galvanic effect may notably damage associated micro-electro-mechanical devices fabricated with processes involving electrochemical steps. This effect is commonly observed when a significant amount of gold is used to design MEMS devices that are fabricated using PolyMUMPsreg. To study and overcome the galvanic effect on these devices, three methods are proposed: (1) connecting the device to a poly0 ring; (2) increasing the device surface area and (3) grounding the device to the substrate. The three methods are compared for their effectiveness in preventing galvanic corrosion. It is observed that although all three methods can considerably restrain the galvanic effect, grounding the device to the substrate is the best solution.