Hollow/porous nanoparticles, including nanocarriers, nanoshells, and mesoporous materials have applications in catalysis, photonics, biosensing, and delivery of theranostic agents. Using a hierarchical template synthesis scheme, we have synthesized a nanocarrier mimicking a golf ball, consisting of (i) solid silica core with a pitted gold surface and (ii) a hollow/porous gold shell without silica. The template consisted of 100 nm polystyrene beads attached to a larger silica core. Selective gold plating of the core followed by removal of the polystyrene beads produced a golf ball-like nanostructure with 100 nm pits. Dissolution of the silica core produced a hollow/porous golf ball-like nanostructure.

Composite colloidal structures with multi-functional properties have wide applications in targeted delivery of therapeutics and imaging contrast molecules and high-throughput molecular bio-sensing. We have constructed a multifunctional composite magnetic nanobowl using bottom-up approach on an asymmetric silica/polystyrene Janus template consisting of a silica shell around a partially exposed polystyrene core. The nanobowl consists of a silica bowl and a gold exterior shell with iron oxide magnetic nanoparticles sandwiched between the silica and gold shells. Nanobowls were characterized by electron microscopy, atomic force microscopy, magnetometry, vis-NIR and FTIR spectroscopy. Magnetically vectored transport of these nanobowls was ascertained by time-lapsed imaging of their flow in fluid through a porous hydrogel under a defined magnetic field. These magnetically-responsive nanobowls show distinct surface enhanced Raman spectroscopy (SERS) imaging capability. PEGylated magnetically-responsive nanobowls show size-dependent cellular uptake in-vitro.

SummaryDigital health promises a paradigm shift for medicine where biomarkers in individuals are continuously monitored to improve diagnosis and treatment of disease. To that end, a technology for minimally invasive quantification of endogenous analytes in bodily fluids will be required. Here, we describe a strategy for designing and fabricating hydrogel microfilaments that can penetrate the skin while allowing for optical fluorescence sensing. The polyacrylamide formulation was selected to provide high elastic modulus in the dehydrated state and optical transparency in the hydrated state. The microfilaments can be covalently tethered to a fluorescent aptamer to enable functional sensing. The microfilament array can penetrate the skin with low pain and without breaking, contact the dermal interstitial fluid, and be easily removed from the skin. In the future, hydrogel microfilaments could be integrated with a wearable fluorometer to serve as a platform for continuous, minimally invasive monitoring of intradermal biomarkers.

Advances in mobile biosensors, integrating developments in materials science and instrumentation, are fueling an expansion in health data being collected and analyzed in decentralized settings. For example, semiconductor‐based sensors are enabling measurement of vital signs, and microfluidic‐based sensors are enabling measurement of biochemical markers. As biosensors for mobile health are becoming increasingly paired with smart devices, it can become critical for researchers to design biosensors—with appropriate functionalities and specifications—to work seamlessly with accompanying connected hardware and software. Here, recent research in biosensors, as well as current mobile health devices in use is described and classified into four distinct system architectures that take into account the biosensing and data processing functions required in personal mobile health devices. The path forward for integrating biosensors into smartphone‐based mobile health devices is also discussed.

Colloidal particles with asymmetric surface chemistry (Janus particles) have unique bifunctional properties. The size of these particles is an important determinant for their applications in diverse fields from drug delivery to chemical catalysis. The size of Janus particles, with a core surface coated with carboxylate and a partially encapsulating silica shell, depends upon several factors, including the core size and the concentration of carboxylate coating. The role of the carboxylate coating on the Janus particle size is well-understood; however, the role of the core size is not well defined. The role of the carboxylated polystyrene (cPS) core size on the cPS-silica Janus particle morphology (its size and shape) was examined by testing two different silica sizes and five different cPS core sizes. Results from electron microscopy (EM) and dynamic light scattering (DLS) analysis indicate that the composite cPS-silica particle acquires two distinct shapes: (i) when the size of the cPS core is much smaller than the non-cPS silica (b-SiO2) sphere, partially encapsulated Janus particles are formed, and (ii) when the cPS core is larger than or equal to the b-SiO2 sphere, a raspberry-like structure rather than a Janus particle is formed. The cPS-silica Janus particles of ∼100-500 nm size were obtained when the size of the cPS core was much smaller than the non-cPS silica (b-SiO2) sphere. These scalable nanoscale Janus particles will have wide application in a multifunctional delivery platform and catalysis.