Gold Nanoparticle Smartphone Platform for Diagnosing Urinary Tract Infections.

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 105 bacteria/mL using bacteria-specific and universal probes. We validated the diagnostic technology using 115 positive and 19 negative samples from patients with Escherichia coli, Proteus mirabilis, and Klebsiella pneumoniae infections. The assay successfully identified the infecting pathogen (specificity: >98% and sensitivity: 51-73%) in 3 h. Our platform is faster than culturing and can wirelessly store and transmit results at the cost of $0.38 per assay.

A Colorimetric Test to Differentiate Patients Infected with Influenza from COVID-19.

Patients infected with SARS-CoV-2 and influenza display similar symptoms, but treatment requirements are different. Clinicians need to accurately distinguish SARS-CoV-2 from influenza to provide appropriate treatment. Here, the authors develope a color-based technique to differentiate between patients infected with SARS-CoV-2 and influenza A using a nucleic acid enzyme-gold nanoparticle (GNP) molecular test requiring minimal equipment. The MNAzyme and GNP probes are designed to be robust to viral mutations. Conserved regions of the viral genomes are targeted, and two MNAzymes are created for each virus. The ability of the system to distinguish between SARS-CoV-2 and influenza A using 79 patient samples is tested. When detecting SARS-CoV-2 positive patients, the clinical sensitivity is 90%, and the specificity is 100%. When detecting influenza A, the clinical sensitivity and specificity are 93% and 100%, respectively. The high clinical performance of the MNAzyme-GNP assay shows that it can be used to help clinicians choose effective treatments.

Diagnosing Antibiotic Resistance Using Nucleic Acid Enzymes and Gold Nanoparticles.

The rapid and accurate detection of antimicrobial resistance is critical to limiting the spread of infections and delivering effective treatments. Here, we developed a rapid, sensitive, and simple colorimetric nanodiagnostic platform to identify disease-causing pathogens and their associated antibiotic resistance genes within 2 h. The platform can detect bacteria from different biological samples (i.e., blood, wound swabs) with or without culturing. We validated the multicomponent nucleic acid enzyme-gold nanoparticle (MNAzyme-GNP) platform by screening patients with central line associated bloodstream infections and achieved a clinical sensitivity and specificity of 86% and 100%, respectively. We detected antibiotic resistance in methicillin-resistant Staphylococcus aureus (MRSA) in patient swabs with 90% clinical sensitivity and 95% clinical specificity. Finally, we identified mecA resistance genes in uncultured nasal, groin, axilla, and wound swabs from patients with 90% clinical sensitivity and 95% clinical specificity. The simplicity and versatility for detecting bacteria and antibiotic resistance markers make our platform attractive for the broad screening of microbial pathogens.

Pulmonary fate and consequences of transferrin-functionalized gold nanoparticles.

Surface functionalization of nanoparticles (NPs) may alter their biological interactions such as uptake by alveolar macrophages (AMs). Pulmonary delivery of gold NPs (Au NPs) has theranostic potential due to their optoelectronic properties, minimal alveoli to blood translocation, and possibility of specific cell targeting. Here, we examined whether coating Au NPs with transferrin alters their protein corona, uptake by macrophages, and pulmonary translocation. Methods: Rats were intratracheally instilled with transferrin-coated Au NPs (Tf-Au NPs) or polyethylene glycol-coated Au NPs (PEG-Au NPs). AMs were collected and processed for quantitation of Au cell uptake using ICP-MS and electron microscopy. Au retention in the lungs and other organs was also determined. The uptake of fluorescently labeled Tf-Au NPs and PEG-Au NPs by monocyte-derived human macrophages was also evaluated in vitro. Results: We showed that Tf-Au NPs were endocytosed by AMs and were retained in the lungs to a greater extent than PEG-Au NPs. Both Au NPs acquired similar protein coronas after incubation in rat broncho-alveolar lavage fluid (BALf). The translocation of Au from both NPs to other organs was less than 0.5% of the instilled dose. Transferrin coating enhanced the uptake of Au NPs by primary monocyte-derived human macrophages. Conclusions: We report that coating of NP surface with transferrin can target them to rat AMs and human monocyte-derived macrophages. NP functionalization with transferrin may enhance NP-based therapeutic strategies for lung diseases.

Nanoparticle Uptake in a Spontaneous and Immunocompetent Woodchuck Liver Cancer Model.

There is a tremendous focus on the application of nanomaterials for the treatment of cancer. Nonprimate models are conventionally used to assess the biomedical utility of nanomaterials. However, these animals often lack an intact immunological background, and the tumors in these animals do not develop spontaneously. We introduce a preclinical woodchuck hepatitis virus-induced liver cancer model as a platform for nanoparticle (NP)-based in vivo experiments. Liver cancer development in these out-bred animals occurs as a result of persistent viral infection, mimicking human hepatitis B virus-induced HCC development. We highlight how this model addresses key gaps associated with other commonly used tumor models. We employed this model to (1) track organ biodistribution of gold NPs after intravenous administration, (2) examine their subcellular localization in the liver, (3) determine clearance kinetics, and (4) characterize the identity of hepatic macrophages that take up NPs using RNA-sequencing (RNA-seq). We found that the liver and spleen were the primary sites of NP accumulation. Subcellular analyses revealed accumulation of NPs in the lysosomes of CD14+ cells. Through RNA-seq, we uncovered that immunosuppressive macrophages within the woodchuck liver are the major cell type that take up injected NPs. The woodchuck-HCC model has the potential to be an invaluable tool to examine NP-based immune modifiers that promote host anti-tumor immunity.

State of diagnosing infectious pathogens using colloidal nanomaterials.

Infectious diseases are a major global threat that accounts for one of the leading causes of global mortality and morbidity. Prompt diagnosis is a crucial first step in the management of infectious threats, which aims to quarantine infected patients to avoid contacts with healthy individuals and deliver effective treatments prior to further spread of diseases. This review article discusses current advances of diagnostic systems using colloidal nanomaterials (e.g., gold nanoparticles, quantum dots, magnetic nanoparticles) for identifying and differentiating infectious pathogens. The challenges involved in the clinical translation of these emerging nanotechnology based diagnostic devices will also be discussed.

Controlling DNA-nanoparticle serum interactions.

Understanding the interaction of molecularly assembled nanoparticles with physiological fluids is critical to their use for in vivo delivery of drugs and contrast agents. Here, we systematically investigated the factors and mechanisms that govern the degradation of DNA on the nanoparticle surface in serum. We discovered that a higher DNA density, shorter oligonucleotides, and thicker PEG layer increased protection of DNA against serum degradation. Oligonucleotides on the surface of nanoparticles were highly resistant to DNase I endonucleases, and degradation was carried out exclusively by protein-mediated exonuclease cleavage and full-strand desorption. These results enabled the programming of the degradation rates of the DNA-assembled nanoparticle system from 0.1 to 0.7 h-1 and the engineering of superstructures that can release two different preloaded dye molecules with distinct kinetics and half-lives ranging from 3.3 to 9.8 h. This study provides a general framework for investigating the serum stability of DNA-containing nanostructures. The results advance our understanding of engineering principles for designing nanoparticle assemblies with controlled in vivo behavior and present a strategy for storage and multistage release of drugs and contrast agents that can facilitate the diagnosis and treatment of cancer and other diseases.

DNA assembly of nanoparticle superstructures for controlled biological delivery and elimination.

The assembly of nanomaterials using DNA can produce complex nanostructures, but the biological applications of these structures remain unexplored. Here, we describe the use of DNA to control the biological delivery and elimination of inorganic nanoparticles by organizing them into colloidal superstructures. The individual nanoparticles serve as building blocks, whose size, surface chemistry and assembly architecture dictate the overall superstructure design. These superstructures interact with cells and tissues as a function of their design, but subsequently degrade into building blocks that can escape biological sequestration. We demonstrate that this strategy reduces nanoparticle retention by macrophages and improves their in vivo tumour accumulation and whole-body elimination. Superstructures can be further functionalized to carry and protect imaging or therapeutic agents against enzymatic degradation. These results suggest a different strategy to engineer nanostructure interactions with biological systems and highlight new directions in the design of biodegradable and multifunctional nanomedicine.