11 research outputs found
A fluorescent switch for sequentially and selectively sensing copper(II) and L-histidine in vitro and in living cells
National Natural Science Foundation of China [21175122, 91127036, 21375121]; Fundamental Research Funds for Central Universities [WK2060190018]Herein, we report the development of a new fluorescent switch for sequential and selective sensing of Cu2+ and L-histidine (L-His) in vitro and in living cells for the first time. In the absence of metal ions, Ac-SAACQ- Gly-Gly-Gly-Lys (FITC) (1) exhibits comparable fluorescence to that of free FITC. In the presence of metal ions, 1 selectively coordinates to Cu2+, causing its fluorescence emission to be quenched via photoinduced electron transfer. Interestingly, the as-formed 1-Cu2+ complex selectively responds to L-His among the 20 natural amino acids by turning its fluorescence on. This property of fluorescence switch of 1 was successfully applied for qualitatively and quantitatively sensing Cu2+ and L-His in vitro. Using this dual functional probe, we also sequentially imaged Cu2+ and L-His in living HepG2 cells. Our new probe 1 could be applied for not only environmental monitoring but also biomolecule detection in the near future
Synchronized Assembly of Gold Nanoparticles Driven by a Dynamic DNA-Fueled Molecular Machine
A strategy for gold nanoparticle (AuNP) assembly driven
by a dynamic
DNA-fueled molecular machine is revealed here. In this machine, the
aggregation of DNA-functionalized AuNPs is regulated by a series of
toehold-mediated strand displacement reactions of DNA. The aggregation
rate of the AuNPs can be regulated by controlling the amount of oligonucleotide
catalyst. The versatility of the dynamic DNA-fueled molecular machine
in the construction of two-component “OR” and “AND”
logic gates has been demonstrated. This newly established strategy
may find broad potential applications in terms of building up an “interface”
that allows the combination of the strand displacement-based characteristic
of DNA with the distinct assembly properties of inorganic nanoparticles,
ultimately leading to the fabrication of a wide range of complex multicomponent
devices and architectures
Electrohydrodynamic Drying of Chinese Wolfberry in a Multiple Needle-to-Plate Electrode System
In order to systematically and comprehensively investigate electrohydrodynamic (EHD) drying characteristics and mechanisms in a multiple needle-to-plate electrode system, drying experiments of Chinese wolfberry were conducted by blocking ionic wind and changing needle spacing in a multiple needle-to-plate electrode system. Drying characteristics, quality parameters, and the microstructure of Chinese wolfberry fruits were measured. Results show that ionic wind plays a very important role during the drying process. Drying rates of different needle spacing treatments are significantly higher than that of the control, and the drying rate decreases with the increase of needle spacing. Needle spacing has a great influence on the speed of ionic wind, rehydration rate, and polysaccharide contents. The effective moisture diffusion coefficient and the electrical conductivity disintegration index decreases with an increase in needle spacing. Ionic wind has a great influence on the effective moisture diffusion coefficient and the electrical conductivity disintegration index of Chinese wolfberry fruits. The microstructure of Chinese wolfberry fruits dried in an EHD system significantly changed. This study provides a theoretical basis and practical guidance for understanding characteristic parameters and mechanisms of EHD drying technology
Infrared Spectrum Analysis of Goji Berry during Electrohydrodynamic Drying
This paper aims to study the effects of different needle spacings on goji berry structure during electrohydrodynamic (EHD) drying. The drying characteristics and the product quality parameters of goji berry during the drying process were measured. The infrared spectrum of the dried product was analyzed in detail. The results showed that the average drying rate of goji berry under different needle spacing conditions was significantly higher than that of the control group, and the average drying rate decreased with the increase of needle spacing. The change of needle spacing has great influence on goji berry polysaccharide content and flavonoid content. Fourier transform infrared spectroscopy showed that the infrared spectra of goji berry in each treatment group were generally similar. The first-order infrared spectra of different treatment groups were mainly different in the range of 1740 cm−1 and 2800 cm−1–2950 cm−1. The shape and intensity of the absorption peaks of the second derivative infrared spectrum of goji berry in different needle spacing treatment groups were different. When the needle spacing is 2 cm and 4 cm, there is a highly variant peak ratio and a low common peak ratio, which proves that the best drying effect is at 2 cm and 4 cm. It provides experimental and theoretical basis for the study of the application and drying mechanism of infrared spectroscopy in the field of electrohydrodynamic drying
Paclitaxel-loaded redox-sensitive nanoparticles based on hyaluronic acid-vitamin E succinate conjugates for improved lung cancer treatment
Integrating DNA-Strand-Displacement Circuitry with Self-Assembly of Spherical Nucleic Acids
Programmable
and algorithmic behaviors of DNA molecules allow one
to control the structures of DNA-assembled materials with nanometer
precision and to construct complex networks with digital and analog
behaviors. Here we developed a way of integrating a DNA-strand-displacement
circuit with self-assembly of spherical nucleic acids, wherein a single
DNA strand was used to initiate and catalyze the operation of upstream
circuits to release a single strand that subsequently triggers self-assembly
of spherical nucleic acids in downstream circuits, realizing a programmable
kinetic control of self-assembly of spherical nucleic acids. Through
utilizing this method, single-nucleotide polymorphisms or indels occurring
at different positions of a sequence of oligonucleotide were unambiguously
discriminated. We provide here a sophisticated way of combining the
DNA-strand-displacement-based characteristic of DNA with the distinct
assembly properties of inorganic nanoparticles, which may find broad
potential applications in the fabrication of a wide range of complex
multicomponent devices and architectures
What Controls the “Off/On Switch” in the Toehold-Mediated Strand Displacement Reaction on DNA Conjugated Gold Nanoparticles?
In DNA dynamic nanotechnology, a
toehold-mediated DNA strand-displacement
reaction has demonstrated its capability in building complex autonomous
system. In most cases, the reaction is performed in pure DNA solution
that is essentially a one-phase system. In the present work, we systematically
investigated the reaction in a heterogeneous media, in which the strand
that implements a displacing action is conjugated on gold nanoparticles.
By monitoring the kinetics of spherical nucleic acid (SNA) assembly
driven by toehold-mediated strand displacement reaction, we observed
significant differences, i.e., the abrupt jump in behavior of an “off/on
switch”, in the reaction rate when the invading toehold was
extended to eight bases from seven bases. These phenomena are attributed
to the effect of steric hindrance arising from the high density of
invading strand conjugated to AuNPs. Based on these studies, an INHIBIT
logic gate presenting good selectivity was developed
Noninvasive and Spatiotemporal Control of DNAzyme-Based Imaging of Metal Ions <i>In Vivo</i> Using High-Intensity Focused Ultrasound
Detecting metal ions invivo with a high spatiotemporal resolution is critical to understanding the roles of the metal ions in both healthy and disease states. Although spatiotemporal controls of metal-ion sensors using light have been demonstrated, the lack of penetration depth in tissue and in vivo has limited their application. To overcome this limitation, we herein report the use of high-intensity focused ultrasound (HIFU) to remotely deliver on-demand, spatiotemporally resolved thermal energy to activate the DNAzyme sensors at the targeted region both in vitro and in vivo. A Zn2+-selective DNAzyme probe is inactivated by a protector strand to block the formation of catalytic enzyme structure, which can then be activated by an HIFU-induced increase in the local temperature. With this design, Zn2+-specific fluorescent resonance energy transfer (FRET) imaging has been demonstrated by the new DNAzyme-HIFU probes in both HeLa cells and mice. The current method can be applied to monitor many other metal ions for in vivo imaging and medical diagnosis using metal-specific DNAzymes that have either been obtained or can be selected using in vitro selection