13 research outputs found
A Simple Method to Fabricate the Highly Sensitive SERS Substrate by Femtosecond Laser-Based 3D Printer
Surface-enhanced Raman spectroscopy (SERS) is a potent technique for analyzing and detecting various targets, including toxic ions, pesticides, and biomarkers, at the single-molecule level. The efficiency of SERS techniques relies heavily on the underlying SERS substrate, which is primarily responsible for the strong induction of localized plasmon resonance on nanostructures. Noble metals such as gold and silver were commonly used to fabricate SERS substrates, leveraging the electromagnetic mechanism (EM) to enhance the Raman signal. However, chemically synthesized nanoparticle-based SERS substrates suffer from low uniformity and reproducibility. Furthermore, the high cost associated with noble metals makes most SERS substrates expensive to produce. In this study, we present a straightforward method for fabricating a highly uniform and reproducible SERS substrate using a femtosecond laser-based 3D printer. Notably, our method offers good cost competitiveness since it requires only a minimal amount of gold coating for the SERS signal. Moreover, the proposed method exhibits exceptional versatility in SERS analysis and detection, catering to numerous targets in the field
Optimization of Field-Free Point Position, Gradient Field and Ferromagnetic Polymer Ratio for Enhanced Navigation of Magnetically Controlled Polymer-Based Microrobots in Blood Vessel
Microscale and nanoscale robots, frequently referred to as future cargo systems for targeted drug delivery, can effectively convert magnetic energy into locomotion. However, navigating and imaging them within a complex colloidal vascular system at a clinical scale is exigent. Hence, a more precise and enhanced hybrid control navigation and imaging system is necessary. Magnetic particle imaging (MPI) has been successfully applied to visualize the ensemble of superparamagnetic nanoparticles (MNPs) with high temporal sensitivity. MPI uses the concept of field-free point (FFP) mechanism in the principal magnetic field. The gradient magnetic field (|∇B|) of MPI scanners can generate sufficient magnetic force in MNPs; hence, it has been recently used to navigate nanosized particles and micron-sized swimmers. In this article, we present a simulation analysis of the optimized navigation of an ensemble of microsized polymer MNP-based drug carriers in blood vessels. Initially, an ideal two-dimensional FFP case is employed for the basic optimization of the FFP position to achieve efficient navigation. Thereafter, a nine-coil electromagnetic actuation simulation system is developed to generate and manipulate the FFP position and |∇B|. Under certain vessel and fluid conditions, the particle trajectories of different ferromagnetic polymer ratios and |∇B| were compared to optimize the FFP position
Wearable Localized Surface Plasmon Resonance-Based Biosensor with Highly Sensitive and Direct Detection of Cortisol in Human Sweat
Wearable biosensors have the potential for developing individualized health evaluation and detection systems owing to their ability to provide continuous real-time physiological data. Among various wearable biosensors, localized surface plasmon resonance (LSPR)-based wearable sensors can be versatile in various practical applications owing to their sensitive interactions with specific analytes. Understanding and analyzing endocrine responses to stress is particularly crucial for evaluating human performance, diagnosing stress-related diseases, and monitoring mental health, as stress takes a serious toll on physiological health and psychological well-being. Cortisol is an essential biomarker of stress because of the close relationship between cortisol concentration in the human body and stress level. In this study, a flexible LSPR biosensor was manufactured to detect cortisol levels in the human body by depositing gold nanoparticle (AuNP) layers on a 3-aminopropyltriethoxysilane (APTES)-functionalized poly (dimethylsiloxane) (PDMS) substrate. Subsequently, an aptamer was immobilized on the surface of the LSPR substrate, enabling highly sensitive and selective cortisol capture owing to its specific cortisol recognition. The biosensor exhibited excellent detection ability in cortisol solutions of various concentrations ranging from 0.1 to 1000 nM with a detection limit of 0.1 nM. The flexible LSPR biosensor also demonstrated good stability under various mechanical deformations. Furthermore, the cortisol levels of the flexible LSPR biosensor were also measured in the human epidermis before and after exercise as well as in the morning and afternoon. Our biosensors, which combine easily manufactured flexible sensors with sensitive cortisol-detecting molecules to measure human stress levels, could be versatile candidates for human-friendly products
Integrated Microalgae Analysis Photobioreactor for Rapid Strain Selection
Algal
photosynthesis is considered to be a sustainable, alternative,
and renewable solution to generating green energy. For high-productivity
algaculture in diverse local environments, a high-throughput screening
method is needed to select algal strains from naturally available
or genetically engineered strains. Herein, we present an integrated
plasmonic photobioreactor for rapid, high-throughput screening of
microalgae. Our 3D nanoplasmonic optical cavity-based photobioreactor
permits the amplification of a selective wavelength favorable to photosynthesis
in the cavity. The hemispheric plasmonic cavity allows intercellular
interaction to be promoted in the optically favorable milieu and also
permits effective visual examination of algal growth. Using Chlamydomonas reinhardtii, we demonstrated a 2-fold
enhanced growth rate and a 1.5-fold lipid production rate with no
distinctive lag phase. By facilitating growth and biomass conversion
rates, the integrated microalgae analysis platform will serve as rapid
microalgae screening platforms for biofuel applications
Asymmetric Nanocrescent Antenna on Upconversion Nanocrystal
Frequency
upconversion activated with lanthanide has attracted
attention in various real-world applications, because it is far simpler
and more efficient than traditional nonlinear susceptibility-based
frequency upconversion, such as second harmonic generation. However,
the quantum yield of frequency upconversion of lanthanide-based upconversion
nanocrystals remains inefficient for practical applications, and spatial
control of upconverted emission is not yet developed. Here, we developed
an asymmetric nanocrescent antenna on upconversion nanocrystal (ANAU)
to deliver excitation light effectively to the core of upconversion
nanocrystal by nanofocusing light and generating asymmetric frequency
upconverted emission concentrated toward the tip region. ANAUs were
fabricated by high-angle deposition (60°) of gold (Au) on the
isolated upconversion nanoparticles supported by nanopillars then
moved to refractive-index matched substrate for orientation-dependent
upconversion luminescence analysis in the single-nanoparticle scale.
We studied shape-dependent nanofocusing efficiency of nanocrescent
antennae as a function of the tip-to-tip distance by modulating the
deposition angle. The generation of asymmetric frequency upconverted
emission toward the tip region was simulated by the asymmetric far-field
radiation pattern of dipoles in the nanocrescent antenna and experimentally
demonstrated by the orientation-dependent photon intensity of frequency
upconverted emission of an ANAU. This finding provides a new way to
improve frequency upconversion using an antenna, which locally increases
the excitation light and generates the radiation power to certain
directions for various applications
Microrobot with Gyroid Surface and Gold Nanostar for High Drug Loading and Near-Infrared-Triggered Chemo-Photothermal Therapy
The use of untethered microrobots for precise synergistic anticancer drug delivery and controlled release has attracted attention over the past decade. A high surface area of the microrobot is desirable to achieve greater therapeutic effect by increasing the drug load. Therefore, various nano- or microporous microrobot structures have been developed to load more drugs. However, as most porous structures are not interconnected deep inside, the drug-loading efficiency may be reduced. Here, we propose a magnetically guided helical microrobot with a Gyroid surface for high drug-loading efficiency and precise drug delivery. All spaces inside the proposed microrobot are interconnected, thereby enabling drug loading deep inside the structure. Moreover, we introduce gold nanostars on the microrobot structure for near-infrared-induced photothermal therapy and triggering drug release. The results of this study encourage further exploration of a high loading efficiency in cell-based therapeutics, such as stem cells or immune cells, for microrobot-based drug-delivery systems
Single-Step LRET Aptasensor for Rapid Mycotoxin Detection
Contamination
of foods by mycotoxins is a common yet serious problem.
Owing to the increase in consumption of fresh produce, consumers have
become aware of food safety issues caused by mycotoxins. Therefore,
rapid and sensitive mycotoxin detection is in great demand in fields
such as food safety and public health. Here we report a single-step
luminescence resonance energy transfer (LRET) aptasensor for mycotoxin
detection. To accomplish the single-step sensor, our sensor was constructed
by linking a quencher-labeled aptamer through a linker to the surface
of upconversion nanoparticles (UCNPs). Our LRET aptasensor is composed
of Mn<sup>2+</sup>-doped NaYF<sub>4</sub>:Yb<sup>3+</sup>,Er<sup>3+</sup> UCNPs as the LRET donor, and black hole quencher 3 (BHQ3) as the
acceptor. The maximum quenching efficiency is obtained by modulating
the linker length, which controls the distance between the quencher
and the UCNPs. Our distinctive design of LRET aptasensor allows detection
of mycotoxins selectively in colored food samples within 10 min without
multiple bioassay steps. We believe our single-step aptasensor has
a significant potential for on-site detection of food contaminants,
environmental pollutants, and biological metabolites