Microfluidic SERS biosensor based on Au-semicoated photonic crystals for melanoma diagnosis.

Surface-enhanced Raman scattering (SERS) shows great promise for early diagnosis due to its high specificity and rapid detection capabilities. However, its application is often hindered by substrate instability and insufficient interaction between the substrate and incident light. To address these challenges, a photonic-plasmonic strategy is often employed to enhance sensing performance but it is generally limited by the low efficiency of plasmonic metal and optical cavity resonances.

Small-scale magnetic soft robotic catheter for in-situ biomechanical force sensing.

Miniaturized magnetic soft robotic catheters offer significant potential in minimally invasive surgery by enabling remote active steering and reduced radiation exposure. However, existing magnetic catheters are limited by the absence of in-situ biomechanical force sensing, which is crucial for controlling the contact force exerted on surrounding tissues during surgical procedures. Here, we report an in-situ force sensing strategy for small-scale magnetic robotic catheters.

Flow tweezing of anisotropic magnetic microrobots in a dynamic magnetic trap for active retention and localized flow sensing.

Controlled manipulation of microscale robotic devices in complex fluidic networks is critical for various applications in biomedical endovascular sensing, lab-on-chip biochemical assays, and environmental monitoring. However, achieving controlled transport and active retention of microscale robots with flow sensing capability has proven to be challenging. Here, we report the dynamic tweezing of an anisotropic magnetic microrobot in a rotating magnetic trap for active retention and localized flow sensing under confined fluidic conditions.

Modular DNAzymes-Hydrogel Membrane Carriers for Highly Sensitive Isothermal Cross-Cascade Detection of Pathogenic Bacteria Nucleic Acids.

The increasing prevalence of antimicrobial resistance has called for improved diagnostic testing of pathogenic bacteria. However, the development of rapid, cost-effective, and easy-to-use tests for bacterial infections remains a constant challenge. Here, we report a class of modular hydrogel membrane carriers incorporated with composite DNAzymes, which enable rapid and highly sensitive detection of pathogenic bacteria gene target analytes.

Responsive Magnetic Nanocomposites for Intelligent Shape-Morphing Microrobots.

With the development of advanced biomedical theragnosis and bioengineering tools, smart and soft responsive microstructures and nanostructures have emerged. These structures can transform their body shape on demand and convert external power into mechanical actions. Here, we survey the key advances in the design of responsive polymer-particle nanocomposites that led to the development of smart shape-morphing microscale robotic devices.

Aspect Ratio of PEGylated Upconversion Nanocrystals Affects the Cellular Uptake In Vitro and In Vivo.

The central nervous system (CNS) is protected by the blood-brain barrier (BBB), which acts as a physical barrier to regulate and prevent the uptake of endogenous metabolites and xenobiotics. However, the BBB prevents most non-lipophilic drugs from reaching the CNS following systematic administration. Therefore, there is considerable interest in identifying drug carriers that can maintain the biostability of therapeutic molecules and target their transport across the BBB.

Single Small Extracellular Vesicle (sEV) Quantification by Upconversion Nanoparticles.

Cancer-derived small extracellular vesicles (sEVs) are potential circulating biomarkers in liquid biopsies. However, their small sizes, low abundance, and heterogeneity in molecular makeups pose major technical challenges for detecting and characterizing them quantitatively. Here, we demonstrate a single-sEV enumeration platform using lanthanide-doped upconversion nanoparticles (UCNPs).

Responsive Sensors of Upconversion Nanoparticles.

Upconversion nanoparticles are a class of luminescent materials that convert longer-wavelength near-infrared photons into visible and ultraviolet emissions. They can respond to various external stimuli, which underpins many opportunities for developing the next generation of sensing technologies. In this perspective, the unique stimuli-responsive properties of upconverting nanoparticles are introduced, and their recent implementations in sensing are summarized.

Stratified Disk Microrobots with Dynamic Maneuverability and Proton-Activatable Luminescence for Imaging.

Microrobots can expand our abilities to access remote, confined, and enclosed spaces. Their potential applications inside our body are obvious, ..

Enabling peristalsis of human colon tumor organoids on microfluidic chips.

Peristalsis in the digestive tract is crucial to maintain physiological functions. It remains challenging to mimic the peristaltic microenvironment in gastrointestinal organoid culture. Here, we present a method to model the peristalsis for human colon tumor organoids on a microfluidic chip.

Mammary Tumor Organoid Culture in Non-Adhesive Alginate for Luminal Mechanics and High-Throughput Drug Screening.

Mammary tumor organoids have become a promising in vitro model for drug screening and personalized medicine. However, the dependency on the basement membrane extract (BME) as the growth matrices limits their comprehensive application. In this work, mouse mammary tumor organoids are established by encapsulating tumor pieces in non-adhesive alginate.

Unidirectional intercellular communication on a microfluidic chip.

Cell co-culture serves as a standard method to study intercellular communication. However, random diffusion of signal molecules during co-culture may arouse crosstalk among different types of cells and hide directive signal-target responses. Here, a microfluidic chip is proposed to study unidirectional intercellular communication by spatially controlling the flow of the signal molecules.

Nanorods with multidimensional optical information beyond the diffraction limit.

Precise design and fabrication of heterogeneous nanostructures will enable nanoscale devices to integrate multiple desirable functionalities. But due to the diffraction limit (~200 nm), the optical uniformity and diversity within the heterogeneous functional nanostructures are hardly controlled and characterized. Here, we report a set of heterogeneous nanorods; each optically active section has its unique nonlinear response to donut-shaped illumination, so that one can discern each section with super-resolution.

Coding and decoding stray magnetic fields for multiplexing kinetic bioassay platform.

Polymer microspheres can be fluorescently-coded for multiplexing molecular analysis, but their usage has been limited by fluorescent quenching and bleaching and crowded spectral domain with issues of cross-talks and background interference. Each bioassay step of mixing and separation of analytes and reagents require off-line particle handling procedures. Here, we report that stray magnetic fields can code and decode a collection of hierarchically-assembled beads.

Emerging technologies for profiling extracellular vesicle heterogeneity.

Extracellular vesicles (EVs) are membrane-bound vesicles secreted by most cell types and exist in virtually all bodily fluids. They carry on a wealth of proteomic and genetic information including proteins, lipids, miRNAs, mRNA, non-coding RNA and other molecules from parental cells. Increasing evidence shows that within populations of EVs, their biogenesis, physical characteristics (e.

Gradient-sized control of tumor spheroids on a single chip.

Multicellular tumor spheroids are attracting more attention as a physiologically relevant in vitro tumor model for biomedical research. The size of spheroids is one of the critical parameters related to drug penetration and cellular responses. It remains challenging to generate a large number of gradient-sized spheroids in one culture vessel.

Optical Nanomaterials and Enabling Technologies for High-Security-Level Anticounterfeiting.

Optical nanomaterials have been widely used in anticounterfeiting applications. There have been significant developments powered by recent advances in material science, printing technologies, and the availability of smartphone-based decoding technology. Recent progress in this field is surveyed, including the availability of optical reflection, absorption, scattering, and luminescent nanoparticles.

Quantitative Lateral Flow Strip Sensor Using Highly Doped Upconversion Nanoparticles.

Paper-based lateral flow assays, though being low-cost and widely used for rapid in vitro diagnostics, are indicative and do not provide sufficient sensitivity for the detection and quantification of low abundant biomarkers for early stage cancer diagnosis. Here, we design a compact device to create a focused illumination spot with high irradiance, which activates a range of highly doped 50 nm upconversion nanoparticles (UCNPs) to produce orders of magnitude brighter emissions. The device employs a very low-cost laser diode, simplified excitation, and collection optics and permits a mobile phone camera to record the results.

DNA-mediated anisotropic silica coating of upconversion nanoparticles.

We report a facile approach of using DNA molecules as switches to selectively activate silica coating onto specific facets of upconversion nanoparticles. Being simple and reproducible, this method improves the understanding of the silica coating mechanism and opens up new opportunities for nanomedicine delivery.

Anisotropic functionalization of upconversion nanoparticles.

Despite significant advances toward accurate tuning of the size and shape of colloidal nanoparticles, the precise control of the surface chemistry thereof remains a grand challenge. It is desirable to conjugate functional bio-molecules onto the selected facets of nanoparticles owing to the versatile capabilities rendered by the molecules. We report here facet-selective conjugation of DNA molecules onto upconversion nanoparticles ligand competition reaction.

Bispecific Antibody-Functionalized Upconversion Nanoprobe.

Upconversion nanoparticles (UCNPs) are new optical probes for biological applications. For specific biomolecular recognition to be realized for diagnosis and imaging, the key lies in developing a stable and easy-to-use bioconjugation method for antibody modification. Current methods are not yet satisfactory regarding conjugation time, stability, and binding efficiency.

Encoding Microreactors with Droplet Chains in Microfluidics.

Droplet-based high throughput biomolecular screening and combinatorial synthesis entail a viable indexing strategy to be developed for the identification of each microreactor. Here, we propose a novel indexing scheme based on the generation of droplet sequences on demand to form unique encoding droplet chains in fluidic networks. These codes are represented by multiunit and multilevel droplets packages, with each code unit possessing several distinct signal levels, potentially allowing large encoding capacity.

Microtubular Fuel Cell with Ultrahigh Power Output per Footprint.

A novel realization of microtubular direct methanol fuel cells (µDMFC) with ultrahigh power output is reported by using "rolled-up" nanotechnology. The microtube (Pt-RuO -RUMT) is prepared by rolling up Ru O layers coated with magnetron-sputtered Pt nanoparticles (cat-NPs). The µDMFC is fabricated by embedding the tube in a fluidic cell.

Magnetic sensing platform technologies for biomedical applications.

Detection and quantification of a variety of micro- and nanoscale entities, e.g. molecules, cells, and particles, are crucial components of modern biomedical research, in which biosensing platform technologies play a vital role.