Label-Free Multimodal Protease Detection Based on Protein/Perylene Dye Coassembly and Enzyme-Triggered Disassembly

The development of novel assays for protease sensing plays an important role in clinical diagnostics and therapeutics. Herein, we report a supramolecular platform for label-free protease detection, based on protein/dye self-assembly and enzyme-triggered disassembly. In a typical case, coassembly of protamine sulfate and perylene dye via electrostatic attractions and π–π interactions caused significant colorimetric and fluorescent responses. Subsequent addition of trypsin was found to cleave the amide bonds of protein, triggering the dissociation of protein/dye aggregates and the release of perylene dyes. The enzyme-triggered disassembly was transduced into multiple readouts including absorption, fluorescence, and polarization, which were exploited for trypsin detection and inhibitor testing. This assay was also used for turn-on fluorescence detection of cathepsin B, an enzyme known to be overexpressed in mammalian cancer cells. The integration of supramolecular self-assembly into enzyme detection in this work has provided a novel label-free biosensing platform which is highly sensitive with multimodal readouts. The relative simplicity of the approach avoids the need for time-consuming substrate synthesis, and is also amenable to naked eye detection

Presentation_1_Effect of Modulating Activity of DLPFC and Gender on Search Behavior: A tDCS Experiment.pdf

Studies of search behavior have shown that individuals stop searching earlier and accept a lower point than predicted by the optimal, risk-neutral stopping rule. This behavior may be related to individual risk preferences. Studies have also found correlativity between risk preferences and the dorsolateral prefrontal cortex (DLPFC). As risk attitude plays a crucial role in search behavior, we studied whether modulating the activity of DLPFC, by using a transcranial direct current stimulation (tDCS) device, can change individual search behavior. We performed a sequential search task in which subjects decided when to accept a point randomly drawn from a uniform distribution. A total of 49 subjects (23 females, mean age = 21.84 ± 2.09 years, all right-handed) were recruited at Zhejiang University from May 2017 to September 2017. They repeated the task in 80 trials and received the stimulation at the end of the 40th trial. The results showed that after receiving right anodal/left cathodal stimulation, subjects increased their searching duration, which led to an increase in their accepted point from 778.17 to 826.12. That is, the subjects may have changed their risk attitude to search for a higher acceptable point and received a higher benefit. In addition, the effect of stimulation on search behavior was mainly driven by the female subjects rather than by the male subjects: the female subjects significantly increased their accepted point from 764.15 to 809.17 after right anodal/left cathodal stimulation, while the male subjects increased their accepted point from 794.18 to 845.49, but the change was not significant.</p

Data_Sheet_1_Effect of Modulating Activity of DLPFC and Gender on Search Behavior: A tDCS Experiment.XLSX

Studies of search behavior have shown that individuals stop searching earlier and accept a lower point than predicted by the optimal, risk-neutral stopping rule. This behavior may be related to individual risk preferences. Studies have also found correlativity between risk preferences and the dorsolateral prefrontal cortex (DLPFC). As risk attitude plays a crucial role in search behavior, we studied whether modulating the activity of DLPFC, by using a transcranial direct current stimulation (tDCS) device, can change individual search behavior. We performed a sequential search task in which subjects decided when to accept a point randomly drawn from a uniform distribution. A total of 49 subjects (23 females, mean age = 21.84 ± 2.09 years, all right-handed) were recruited at Zhejiang University from May 2017 to September 2017. They repeated the task in 80 trials and received the stimulation at the end of the 40th trial. The results showed that after receiving right anodal/left cathodal stimulation, subjects increased their searching duration, which led to an increase in their accepted point from 778.17 to 826.12. That is, the subjects may have changed their risk attitude to search for a higher acceptable point and received a higher benefit. In addition, the effect of stimulation on search behavior was mainly driven by the female subjects rather than by the male subjects: the female subjects significantly increased their accepted point from 764.15 to 809.17 after right anodal/left cathodal stimulation, while the male subjects increased their accepted point from 794.18 to 845.49, but the change was not significant.</p

Controllable Synthesis of Water-Soluble Gold Nanoparticles and Their Applications in Electrocatalysis and Surface-Enhanced Raman Scattering

We report a facile method to synthesize water-soluble gold nanoparticles (AuNPs) using a biosurfactant sodium cholate as reducing reagents and protective groups in aqueous solution at ambient temperature. The diameters (13–70 nm) of uniform AuNPs can be readily adjusted by changing the initial molar ratio of sodium cholate to chloroauric acid (HAuCl4). Also, the alkaline condition of preparative solution is found to affect the size of as-synthesized AuNPs. This synthetic approach is one-step and “green”. The obtained AuNPs exhibit a good electrocatalytic activity toward methanol oxidation. Meanwhile, the AuNPs thin films can serve as an efficient substrate for surface-enhanced Raman scattering (SERS). Furthermore, platinum nanoparticles (PtNPs) are also prepared by reducing sodium tetrachloro platinate hydrate with sodium cholate

Self-Templating of Metal-Driven Supramolecular Self-Assembly: A General Approach toward 1D Inorganic Nanotubes

The rational design of one-dimensional (1D) inorganic nanomaterials directed by self-assembled soft matters is one of the most attractive subjects in modern chemistry. In this work, the self-templating approach based on metal−cholate supramolecular self-assemblies is reported, which is distinct from the traditional soft template method. Under the framework of self-templating, metal ions can serve as both the inorganic precursor and constituent of the template; additional precursors which may change the solution conditions and interfere with the soft templates are not needed. It is demonstrated that self-templating method is a general approach to synthesize a series of 1D inorganic nanotubes including ZnS, CuS, NiS, CdS, CoS, ZnSe, and ZnTe nanotubes. Moreover, the structural diversity and dynamic nature of organic architectures allow the preparation of size and shape-adjustable 1D nanotubes through conveniently temporal and thermal controls. A possible mechanism for nanotube formation is also proposed

Heating-Induced Micelle to Vesicle Transition in the Cationic−Anionic Surfactant Systems: Comprehensive Study and Understanding

Heating-induced micelle to vesicle transition (MVT), which has been rarely reported in surfactant systems, was systemically studied in a number of mixed cationic−anionic surfactant systems. According to the turbidity measurements, the investigated systems can be divided into two classes:  Class A and B. Heating-induced MVT was observed in Class A at certain total surfactant concentrations and mixed surfactant ratios, while no such transition was found in Class B. Further investigations revealed that the heating-induced MVT is more likely to take place in the cationic−anionic surfactant systems with relatively stronger molecule interaction and larger micelle aggregation number. The effects of several physicochemical factors, such as the variation of mixed surfactant ratios and the addition of n-decanol on the heating-induced MVT, were also studied

pH-Regulated Molecular Self-Assemblies in a Cationic−Anionic Surfactant System: From a “1−2” Surfactant Pair to a “1−1” Surfactant Pair

With the aid of pH variation, direct transformation of a “1−1” cationic−anionic surfactant pair to a “1−2” cationic−anionic surfactant pair was attained in the system of cetyltrimethylammonium bromide and n-decylphosphoric acid. Owing to the transformation of a “1−1” pair to a “1−2” pair, diverse microstructures and peculiar phase behavior in this cationic−anionic surfactant mixture was obtained at different pH. It is proposed that pH can be manipulated for effectively tailoring the self-assembled organization in this cationic−anionic surfactant system, including spherical micelle, wormlike micelle, vesicle, and lamellar structure. In contrast to the conventional “1−1” surfactant pair, the “1−2” cationic−anionic surfactant pair exhibits unexpectedly weak aggregating ability. It is suggested that the hydrated volume of surfactant headgroup should be taken into consideration to better elucidate the self-assembly behavior of these “1−2” cationic−anionic surfactant mixtures

Colorimetric Detection of Small Molecules in Complex Matrixes via Target-Mediated Growth of Aptamer-Functionalized Gold Nanoparticles

A versatile and sensitive colorimetric assay that allows the rapid detection of small-molecule targets using the naked eye is demonstrated. The working principle of the assay integrates aptamer–target recognition and the aptamer-controlled growth of gold nanoparticles (Au NPs). Aptamer–target interactions modulate the amount of aptamer strands adsorbed on the surface of aptamer-functionalized Au NPs via desorption of the aptamer strands when target molecules bind with the aptamer. Depending on the resulting aptamer coverage, Au NPs grow into morphologically varied nanostructures, which give rise to different colored solutions. Au NPs with low aptamer coverage grow into spherical NPs, which produce red-colored solutions, whereas Au NPs with high aptamer coverage grow into branched NPs, which produce blue-colored solutions. We achieved visible colorimetric response and nanomolar detection limits for the detection of ochratoxin A (1 nM) in red wine samples, as well as cocaine (1 nM) and 17β-estradiol (0.2 nM) in spiked synthetic urine and saliva, respectively. The detection limits were well within clinically and physiologically relevant ranges, and below the maximum food safety limits. The assay is highly sensitive, specific, and able to detect an array of analytes rapidly without requiring sophisticated equipment, making it relevant for many applications, such as high-throughput drug and clinical screening, food sampling, and diagnostics. Furthermore, the assay is easily adapted as a chip-based platform for rapid and portable target detection

Photoluminescent Lanthanide-Doped Silica Nanotubes: Sol−Gel Transcription from Functional Template

Functional photoluminescent materials have emerged as a fascinating research subject holding great promise in versatile applications. In this report, photoluminescent lanthanide-organic hybrid nanofibers in hydrogels are fabricated through supramolecular self-assembly, which can serve as functional soft templates to prepare inorganic nanomaterials. By using sol−gel transcription of tetraethylorthosilicate (TEOS), novel lanthanide-doped silica nanotubes are conveniently prepared, in which lanthanide ions are embedded into the silica nanotube walls. In this approach, luminescent lanthanide ions transfer from organic nanofibers into inorganic silica nanotubes. Moreover, different kinds of lanthanide-doped silica nanotubes with tunable photoluminescent emission color can be achieved by changing the doping ions such as Tb3+ and co-doping Tb3+/Eu3+ in the soft template. The lanthanide-doped silica nanotubes are potentially used as nanostructured optical devices and sensors

Effects of Inorganic and Organic Salts on Aggregation Behavior of Cationic Gemini Surfactants

All salts studied effectively reduce critical micelle concentration (CMC) values of the cationic gemini surfactants. The ability to promote the surfactant aggregation decreases in the order of C6H5COONa > p-C6H4(COONa)2 > Na2SO4> NaCl. Moreover, only C6H5COONa distinctly reduces both the CMC values and the surface tension at CMC. For 12-4-12 solution, the penetration of C6H5COO− anions and charge neutralization induce a morphology change from micelles to vesicles, whereas the other salts only slightly increase the sizes of micelles. The 12-4(OH)2-12 solution changes from the micelle/vesicle coexistence to vesicles with the addition of C6H5COONa, whereas the other salts transfer the 12-4(OH)2-12 solution from the micelle/vesicle coexistence to micelles. As compared with 12-4-12, the two hydroxyls in the spacer of 12-4(OH)2-12 promote the micellization of 12-4(OH)2-12 and reduce the amounts of C6H5COONa required to induce the micelle-to-vesicle transition