Peptides in the detection of metal ions.

By means of their specific interactions with different metal ions, naturally occurring proteins control structures and functions of many biological processes and functions in organisms. In view of natural metallopeptides, scientists have proposed artificial peptides which coordinate with metal ions through their functional groups either for introducing a special reactivity or for constructing various sensors. However, the design of new peptide ligands requires a deep understanding of the structures, assembly properties, and dynamic behaviors of such peptides.

Double Immobilized Superhydrophobic and Lubricated Slippery Surface with Antibacterial and Antifouling Properties.

A "double immobilized" superhydrophobic and lubricated slippery surface was prepared by simultaneously immobilizing lubricating oil and bactericide molecules. The coordination function of metal organic frameworks (MOFs) was utilized to immobilize trimesic acid, a fungicide, as a ligand of the MOF by the cathodic electrodeposition technique. Aminated silicone oil was used as a lubricating oil and was immobilized to the superhydrophobic MOF film by the curing reaction with isocyanates.

Raman inks based on triple-bond-containing polymeric nanoparticles for security.

Developing security inks with spectral outputs/multiple colors, which have unique identification characteristics, is of great importance in enhancing the anti-counterfeiting strength of ink anti-counterfeiting technology. Herein, a print-driven triple-bond coding mode is proposed for the first time. Two kinds of triple-bond-containing polymeric nanoparticles (NPs) with Raman shifts at 2227 and 2241 cm have been designed into printable ink, and the decimal coding output can be easily obtained by reasonably adjusting the proportions of the two polymeric NPs.

Photoreduced Ag surrounding single poly(4-cyanostyrene) nanoparticles for undifferentiated SERS sensing and killing of bacteria.

Developing a rapid, low cost and sensitive sensing strategy for undifferentiated detection and fast killing of bacterial pathogens are critical to alleviating bacteria infections. Here, we propose a direct photoreduction method to synthesize the SERS tag by integrating poly(4-cyanostyrene) nanoparticles (NPs) and silver ions, which are applied as bio-sensing system for bacteria sensing and fast killing. Under a focused laser spot, silver ions on the surface of the poly(4-cyanostyrene) NPs could be photoreduced into Ag NPs, thereby causing the Raman signal amplification of poly(4-cyanostyrene) NPs up to 40 times, and there is a good linear correlation between the Raman intensity of poly(4-cyanostyrene) NPs and different concentrations of Ag.

Rational synthesis of Three-Layered plasmonic nanocomposites of copper Sulfide/Gold/Zinc-Doped Prussian blue analogues for improved photothermal disinfection and wound healing.

Bacteria-infected wounds have imposed serious challenges in human health whereas the abuse of antibiotics makes bacteria drug-resistant and becoming more and more difficult to deal with. Herein, we developed a drug-free three-layered photothermal bactericide from inside to outside consisting of copper sulfide (CuS), gold (Au) and zinc-doped Prussian blue analogues (ZnPBA) (named as CuS@Au@ZnPBA). The CuS@Au@ZnPBA was demonstrated to possess remarkably-improved photothermal property and excellent biosafety.

A functional peptide-mediated colorimetric assay for mercury ion based on dual-modified gold nanoparticles.

In the work, a rapid and accurate biosensor for mercury ions (Hg) was constructed, with which aggregation of dual-modified (DGPFHR- and CALNN-) gold nanoparticles (D/C-AuNPs) could be triggered by the high specificity of peptides to Hg. The given peptide DGPFHR possesses great capability of capturing Hg, accompanied by the conformational folding. Under the circumstances, D/C-AuNPs were employed as the detection probes to accomplish the quantitative analysis of Hg.

Precise Encoding of Triple-Bond Raman Scattering of Single Polymer Nanoparticles for Multiplexed Imaging Application.

Stimulated Raman scattering (SRS) microscopy in combination with innovative tagging strategies offers great potential as a universal high-throughput biomedical imaging tool. Here, we report rationally tailored small molecular monomers containing triple-bond units with large Raman scattering cross-sections, which can be polymerized at the nanoscale for enhancement of SRS contrast with smaller but brighter optical nanotags with artificial fingerprint output. From this, a class of triple-bond rich polymer nanoparticles (NPs) was engineered by regulating the relative dosages of three chemically different triple-bond monomers in co-polymerization.

A straightforward and reliable evaluation of Ag(I) binding affinity mediated by a peptide ligand for constructing an efficient sensing platform.

The reliable determination of the Ag(I) affinity for biomolecules is an essential issue in the fields of structural analysis and sensor design. However, the urgent problem confronting researchers is lack of a direct and accurate Ag(I) affinity evaluation as a reference standard for ligand analysis. We communicated here a straightforward and high-efficiency method of measuring Ag(I) affinity exactly on the basis of the unique calculation algorithm and the design of a special peptide RFPRDD (P) as Ag(I) binding motif.

Promoted "Click" SERS Detection for Precise Intracellular Imaging of Caspase-3.

Although homogeneous detection of some biomolecules has been of great significance in clinical assay, it faces great challenges in achieving precise imaging of biomolecules. In addition, nonspecific adsorption between probes and biomolecules and low sensitivity are still unfathomed problems. Herein, we developed a promoted "Click" surface enhanced Raman scattering (SERS) strategy for realizing highly selective homogeneous detection of biomolecules by simultaneous dual enhanced SERS emissions, obtaining mutually confirmed logical judgment.

Fine synthesis of Prussian-blue analogue coated gold nanoparticles (Au@PBA NPs) for sorting specific cancer cell subtypes.

Multiplex surface-enhanced Raman scattering (SERS) detection of markers without background in tumor biosystems has its superiority over other optical methods. Herein, we reported a strategy of quantitative discrimination of two breast cancer cell subtypes. Based on our previous studies, two kinds of Prussian blue analogue coated gold nanoparticles (Au@PBA NPs) were designed and synthesized by the replacement of Fe with Pb or Cu.

The small silver nanoparticle-assisted homogeneous sensing of thiocyanate ions with an ultra-wide window based on surface-enhanced Raman-extinction spectroscopy.

For the first time, we present an original sensing strategy with an ultra-wide detection window from 17 nM to 20 mM to detect SCN- ions. Initially, we investigated the clustering and optical properties of noble metal sol nanoparticles (NPs) due to the competitive interaction of thiocyanate ions (SCN-) and cetyltrimethylammonium bromide (CTAB) under weak acidic conditions, and found that different dimensions and scales of nanoclusters containing the alkyne-embedded Au@Ag NPs and relatively small Ag NPs could be achieved by the mediation of CTAB through electrostatic forces and hydrophobic interaction, in which SCN- could be covalently bonded with the silver surface of NPs to form a compact molecular layer (-Ag-S-C[triple bond, length as m-dash]N), and CTAB could only occupy remaining sites. In this process, we found that SCN- always runs counter to CTAB and tends to dissolve nanoclusters, so that they occupy the exposed surface of NPs in nanoclusters rather than the binding sites of one another.

On-site and quantitative SERS detection of trace 1, 2, 3-benzotriazole in transformer oil with colloidal lignin particles-based green pretreatment reagents.

Since 1, 2, 3-Benzotriazole (BTA) is one of the most commonly used metal passivators in transformer oil, on-site and quantitative detection of BTA plays a significant role in fast evaluation of the performance of the insulating oil. Herein, we proposed a cycle-growth synthetic protocol for yielding two-dimensional (2D) plane-based surface-enhanced Raman scattering (SERS) substrates with tunable optical property and controllable interparticle distance, and an extraction material, so called colloidal lignin particles (CLPs), for the fast separation of BTA from oil matrix. After BTA from transformer oil were adsorbed by hydrophilic CLPs, highly reproducible SERS signal of BTA can be obtained by dropping on the substrate.

Nucleic Acid Hybridization-Based Noise Suppression for Ultraselective Multiplexed Amplification of Mutant Variants.

The analysis of mutant nucleic acid (NA) variants can provide crucial clinical and biological insights for many diseases. Yet, existing analysis techniques are generally constrained by nonspecific "noise" signals from excessive wildtype background sequences, especially under rapid isothermal multiplexed target amplification conditions. Herein, the molecular hybridization chemistry between NA bases is manipulated to suppress noise signals and achieve ultraselective multiplexed detection of cancer gene fusion NA variants.

A laser metallurgy route for the batch preparation of mm-scale 3D silver/graphite heteronanoclusters in air.

We report a batch preparation of mm-scale 3D Ag hetero-nanoclusters which exhibit an excellent surface plasmon resonance ability via facile laser metallurgy. Under laser irradiation, the porous AgI-based coordination network crystals were instantly converted into 3D graphite-encapsulated Ag hetero-nanoclusters with uniform sizes and gaps in several seconds. The obtained hetero-nanoclusters exhibited superior 3D confocal laser energy utilization compared with the other 0D, 1D and 2D SERS substrates, solving the bottleneck caused by laser focusing deviation in the SERS active depth.

On-Site and Quantitative Detection of Trace Methamphetamine in Urine/Serum Samples with a Surface-Enhanced Raman Scattering-Active Microcavity and Rapid Pretreatment Device.

Here, it reports a high-throughput detection method for reliably quantitative analysis of illegal drugs in complex biological samples by means of a surface-enhanced Raman scattering (SERS) active microcavity and rapid pretreatment device. Based on the well-made hemispherical microcavities that regularly distributed on a glass array, the quality-controllable microcavity device is fabricated by the compact self-assembly of core-shell nanopeanuts (CSNPs) onto the inside surface. Both the CSNPs with a quantifiable internal standard signal of crystal violet acetate anchored inside their gap and the well-made microcavity referred to the physical amplification of the microscale groove surface will do well in trace analysis, which will allow us to realize the accurately quantitative SERS analysis of targeted analytes spread on the bottom area of the microcavity array.

Monodispersed plasmonic Prussian blue nanoparticles for zero-background SERS/MRI-guided phototherapy.

Surface-enhanced Raman scattering (SERS) and magnetic resonance imaging (MRI)-guided phototherapy are new breakthroughs in cancer therapeutics due to their complementary advantages, such as enhanced imaging spatial resolution and depth. Herein, we synthesized monodispersed Prussian blue-encapsulated gold nanoparticles (Au@PB NPs), in which the plasmonic gold core plus coordination polymer of cyanide (C[triple bond, length as m-dash]N) and iron ions coincidently become a superexcellent contrast agent for both MRI and zero-background SERS imaging. PB, as a signal source for MR and SERS, can be easily assembled onto single Au NPs, of which iron ions possess high relaxation efficiency for in vivo MRI, e.

Combined Surface-Enhanced Raman Scattering Emissions for High-Throughput Optical Labels on Micrometer-Scale Objects.

High-throughput optical labeling technologies have become increasingly important with the growing demands for molecular detection, disease diagnosis, and drug discovery. In this thought, a series of CN-bridged coordination polymer encapsulated gold nanoparticles have been developed as a universal and interference-free optical label through a facile and auxiliary agent-free self-assembly route. Moreover, surface-enhanced Raman scattering (SERS) emissions of CN-bridge can be tuned flexibly by simple replacement of Fe/Fe with other metal ions relying on the synthesis of three Prussian blue analogues encapsulated gold nanoparticles (Au@PBA NPs).

Accurate Clinical Diagnosis of Liver Cancer Based on Simultaneous Detection of Ternary Specific Antigens by Magnetic Induced Mixing Surface-Enhanced Raman Scattering Emissions.

Establishing an accurate, simple, and rapid serodiagnosis method aiming for specific cancer antigens is critically important for the clinical diagnosis, therapy, and prognostication of cancer. Currently, surface-enhanced Raman scattering (SERS) readout techniques challenge fluorescent-based detection methods in terms of both optical stability and more importantly multiple detection capability, which become more desirable for clinical diagnostics. We thus started using an interference-free mixing SERS emission (m-SERS) readout to simultaneously indicate, for the first time, three specific liver cancer antigens, including α-fetoprotein (AFP), carcinoembryonic antigen (CEA), and ferritin (FER), even in one clinical serum sample.

Total Aqueous Synthesis of Au@Cu S Core-Shell Nanoparticles for In Vitro and In Vivo SERS/PA Imaging-Guided Photothermal Cancer Therapy.

Both accurate tumor navigation and nanostructures with high photothermal (PT) conversion efficiency are important but remain challenging to achieve in current biomedical applications. This study reports an anion exchange-based facile and green approach for synthesizing Au@Cu S core-shell nanoparticles (NPs) in an aqueous system. In addition to the PT effect of the suggested NPs, the surface-enhanced Raman scattering (SERS) is also significantly improved due to the tailored localized surface plasmon resonance coupling between the Au metal core and the Cu S semiconductor shell.

Rational synthesis of hollow cubic CuS@Spiky Au core-shell nanoparticles for enhanced photothermal and SERS effects.

Hollow cubic CuS@Spiky Au core-shell nanoparticles (NPs) were rationally synthesized both for guided highly efficient damage to cancer cells by the photothermal effect and for the real-time monitoring of biochemical responses during cellular apoptosis, totally based on label-free SERS intracellular imaging.

Splicing Nanoparticles-Based "Click" SERS Could Aid Multiplex Liquid Biopsy and Accurate Cellular Imaging.

Here, a completely new readout technique, so-called "Click" SERS, has been developed based on Raman scattered light splice derived from nanoparticle (NP) assemblies. The single and narrow (1-2 nm) emission originating from triple bond-containing reporters undergoes dynamic combinatorial output, by means of controllable splice of SERS-active NPs analogous to small molecule units in click chemistry. Entirely different to conventional "sole code related to sole target" readout protocol, the intuitional, predictable and uniquely identifiable "Click" SERS is relies on the number rather than the intensity of combinatorial emissions.

Rational design of an anchoring peptide for high-efficiency and quantitative modification of peptides and DNA strands on gold nanoparticles.

The pentapeptide Cys-Ala-Leu-Asn-Asn (CALNN) could stabilize gold nanoparticles (AuNPs), most of which serve as anchoring blocks for various bioanalyses by introducing recognition blocks. However, the typical conjugation strategy greatly suffers from excessive use of peptides, overnight incubation and consequently low efficiency. In this study, new design criteria for the efficacious anchor were established.

High stability of gold nanoparticles towards DNA modification and efficient hybridization via a surfactant-free peptide route.

With the assistance of peptides, a stable and highly efficient approach for the quick loading of thiol-DNA onto AuNPs is proposed with a high DNA utilization, which is generally applicable to specific DNA detection and diverse AuNP sizes. The maximum efficiency of hybridization reached 93% while the reaction time was shortened to 30 min.

Environmentally Safe Mercury(II) Ions Aided Zero-Background and Ultrasensitive SERS Detection of Dipicolinic Acid.

Field, reliable, and ultrasensitive detection of dipicolinic acid (DPA), a general biomarker of bacterial spores and especially Bacillus anthracis, is highly desirable but still challenging in current biometric security emergency response system. Herein we report an environmentally safe mercury(II) ions-mediated and competitive coordination interaction based approach for rationally designed surface-enhanced Raman scattering (SERS)-active gold nanoparticles (AuNPs), enabling rapid, ultrasensitive and zero-background detection of DPA without the pretreatment of samples. By means of competitiveness, these papain-capped gold nanoparticles (P-AuNPs) are induced to undergo controllable aggregation upon the addition of Hg ions and DPA with a concentration range (1 nM∼8 μM), which correspondingly cause quantitative changes of SERS intensity of cresyl violet acetate (CVa) conjugated AuNPs.