8 research outputs found
Droplet Microfluidic Device for Rapid and Efficient Metals Separation Using Host-Guest Chemistry
Metals are pivotal elements in our daily life and industrial processes, to produce electronic devices, catalysts, smart materials and so on. However, they are mostly present as a mixture in the environment that makes their separation challenging over the past decade. Host-guest chemistry principle thoroughly has been used to design and synthesize thousands of organic receptors with high complexation ability and selectivity to certain metal ions. On the other hand, the droplet microfluidic device is well-known for its unique characteristics of fluid dynamics, such as large specific surface area and short diffusion distance making the process robust and efficient. Therefore, many reports of research employ host-guest chemistry of the droplet microfluidic system for the effective metal separation process. This chapter deals with up-to-date examples of the droplet microfluidic system application for separation of base and alkali metals, recovery of rare-earth and precious metals and removal of heavy metals either from the competitive metal system or from the real waste solution sample through solvent extraction techniques utilizing host-guest chemistry principle
Gold Nanoparticle-Based Surface-Enhanced Raman Scattering for Noninvasive Molecular Probing of Embryonic Stem Cell Differentiation
This study reports the use of gold nanoparticle-based surface-enhanced Raman scattering (SERS) for probing the differentiation of mouse embryonic stem (mES) cells, including undifferentiated single cells, embryoid bodies (EBs), and terminally differentiated cardiomyocytes. Gold nanoparticles (GNPs) were successfully delivered into all 3 mES cell differentiation stages without affecting cell viability or proliferation. Transmission electron microscopy (TEM) confirmed the localization of GNPs inside the following cell organelles: mitochondria, secondary lysosome, and endoplasmic reticulum. Using bright- and dark-field imaging, the bright scattering of GNPs and nanoaggregates in all 3 ES cell differentiation stages could be visualized. EB (an early differentiation stage) and terminally differentiated cardiomyocytes both showed SERS peaks specific to metabolic activity in the mitochondria and to protein translation (amide I, amide II, and amide III peaks). These peaks have been rarely identified in undifferentiated single ES cells. Spatiotemporal changes observed in the SERS spectra from terminally differentiated cardiomyocyte tissues revealed local and dynamic molecular interactions as well as transformations during ES cell differentiation
Optimization of fluorescent cell-based assays for high-throughput analysis using microchamber array chip formats
Droplet-based microreactor system for stepwise recovery of precious metal ions from real metal waste with calix[4]arene derivatives
Separation of Pb(II) Ion with Tetraacetic Acid Derivative of Calix[4]arene by Using Droplet-based Microreactor System
In this study, the microreactor system was investigated and compared with the batch-wise system as rapid and effective extractive Pb(II) separation over Fe(III), Cu(II) and Zn(II) with tetraacetic acid calix[4]arene. By using a microreactor system, the Pb(II) extraction percentages reached the maximum of 73, 89 and 100% in 8 sec residence time at equilibrium pH of 2.00, 2.25 and 2.50, respectively. The stripping percentage was 92% at 8 sec residence time by using a microreactor system with 2.0 M HNO3 as a stripping reagent. Complete separation of Pb(II) over Fe(III), Cu(II) and Zn(II) ions with the tetraacetic acid calix[4]arene in a competitive metal system was achieved at pH 2.00. However, the batch system required 24 h to reach the equilibrium for both extraction and stripping processes. The results suggested that the microreactor system enhanced the Pb(II) extraction and stripping rate up to 104 times faster than the batch-wise system
Controlled Cell Adhesion Using a Biocompatible Anchor for Membrane-Conjugated Bovine Serum Albumin/Bovine Serum Albumin Mixed Layer
We report here a
method for controlling cell adhesion, allowing
simple yet accurate cell detachment from the substrate, which is required
for the establishment of new cytometry-based cell processing and analyzing
methods. A biocompatible anchor for membrane (BAM) was conjugated
with bovine serum albumin (BSA) to produce a cell-anchoring agent
(BAM–BSA). By coating polystyrene substrates with a mixture
of BAM–BSA and BSA, controlled suppression of the substrate’s
adhesive properties was achieved. Hook-shaped nanoneedles were used
to pick up cells from the substrate, while recording the cell–substrate
adhesion force, using an atomic force microscope (AFM). Due to the
lipid bilayer targeting property of BAM, the coated surface showed
constant adhesion forces for various cell lines, and controlling the
BAM–BSA/BSA ratio enabled tuning of the adhesion force, ranging
from several tens of nano-Newtons down to several nano-Newtons. Optimized
tuning of the adhesion force also enabled the detachment of cells
from BAM–BSA/BSA-coated dishes, using a shear flow. Moreover,
the method was shown to be noncell type specific and similar results
were observed using four different cell types, including nonadherent
cells. The attenuation of cell adhesion was also used to enable the
collection of single cells by capillary aspiration. Thus, this versatile
and relatively simple method can be used to control the adhesion of
various cell types to substrates
A New Cell Separation Method Based on Antibody-Immobilized Nanoneedle Arrays for the Detection of Intracellular Markers
Focusing
on intracellular targets, we propose a new cell separation
technique based on a nanoneedle array (NNA) device, which allows simultaneous
insertion of multiple needles into multiple cells. The device is designed
to target and lift (“fish”) individual cells from a
mixed population of cells on a substrate using an antibody-functionalized
NNA. The mechanics underlying this approach were validated by force
analysis using an atomic force microscope. Accurate high-throughput
separation was achieved using one-to-one contacts between the nanoneedles
and the cells by preparing a single-cell array in which the positions
of the cells were aligned with 10,000 nanoneedles in the NNA. Cell-type-specific
separation was realized by controlling the adhesion force so that
the cells could be detached in cell-type-independent manner. Separation
of nestin-expressing neural stem cells (NSCs) derived from human induced
pluripotent stem cells (hiPSCs) was demonstrated using the proposed
technology, and successful differentiation to neuronal cells was confirmed