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Direct synthesis of ultrasmall and stable magnetite nanoparticles coated with one single carbon layer for sensitive surface-enhanced Raman scattering
摘要： Ultrasmall spherical magnetite nanoparticles (Fe3O4 NPs) coated with one single carbon layer (Fe3O4@1C NPs) were directly synthesized by a simple, fast one-step hydrothermal reaction at low temperature (200℃). The as-synthesized Fe3O4@1C NPs were easily separated and purified from the resultant mixture, without the need for any additional energy input and chemicals. The as-purified Fe3O4@1C NPs not only displayed typical superparamagnetic behavior but also exhibited quite good long-term stability after being exposed to the open air under the room conditions for more than 2 months. Importantly, the long-term stored Fe3O4@1C NPs exhibited a highly sensitive surface-enhanced Raman spectroscopy (SERS) response toward Rhodamine-b (RdB) molecules with low concentration. The multifunctional and recyclable Fe3O4@1C NPs presented a prospective application for the selective enrichment and sensitive SERS detection of chemical and biomolecular assays.
关键词： coated with one single carbon layer (Fe3O4@1C NPs),Dehydration reaction,Saturation magnetization,Long-term stability,Magnetite nanoparticles (Fe3O4 NPs)
更新于2025-11-14 17:03:37
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Analysis of TiO <sub/>2</sub> Atomic Layer Deposition Surface Chemistry and Evidence of Propene Oligomerization using Surface-Enhanced Raman Spectroscopy
摘要： Atomic layer deposition (ALD) of TiO2 was performed in tandem with in-situ surface-enhanced Raman spectroscopy (SERS) to monitor changes in the transient surface species across multiple ALD cycles. A self-assembled monolayer of 3-mercaptopropionic acid was used as a capture agent, to ensure that nucleation of the titanium precursor (titanium tetraisopropoxide [TTIP]) occurs. Comparisons between the Raman spectra of the neat precursor and the SER spectra of the 1st ALD cycle of TiO2 reveal typical ligand exchange chemistry taking place, with self-limiting behavior and intact isopropoxide ligands. However subsequent cycles show drastically different chemistry, with no isopropoxide ligands remaining at any point during the 2nd and 3rd cycles. Continuous exposure of either TTIP or isopropanol after the 1st cycle shows unlimited, chemical vapor deposition (CVD)-type growth. Comparisons with alternative precursors (aluminum isopropoxide, titanium tert-butoxide, and titanium propoxide) and DFT calculations reveal that for the TTIP precursor, isolated TiO2 sites play a role in the dehydration of off-gassing isopropanol. The resulting propene then undergoes oligomerization into six-carbon olefins, before polymerizing into indistinguishable carbon products that accumulate on the surface. The emergence of the dehydration chemistry is expected to be exclusively the result of these isolated TiO2 sites, and as such is expected to occur on other surfaces where TiO2 ALD is feasible. This work showcases how seemingly innocuous ALD can evolve into a CVD process when the products can participate in various side reactions with newly made surface sites.
关键词： Oligomerization,TiO2,Surface-enhanced Raman spectroscopy,TTIP,Atomic layer deposition,Dehydration chemistry
更新于2025-09-23 15:19:57
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Real-time laser induced chemical derivatizations of peptide N-Terminus for in-situ mass spectrometric sequencing at sub-picomole and nanosecond scale
摘要： Distinguishing b- and y-ions is essential to compute amino acid sequences from either N- or C-terminus in mass spectrometry. We described herein a solvent free and real time on-plate derivatization approach that can tag N-terminus of peptides at microliter level with p-chlorobenzaldehyde or 2-hydroxy-5-methylisophthalaldehyde for matrix assisted laser desorption ionization mass spectrometry (MALDI MS). Less than 1 mL of sample solutions can be directly mixed with equal volumes of p-chlorobenzaldehyde or 2-hydroxy-5-methylisophthalaldehyde and a-cyano-4-hydroxycinnamic acid (CHCA), a matrix compound to co-crystalize with analytes for efficient absorption of laser energy and peptide ionization. When the mixture spotted on the sample plate is irradiated with the 3rd harmonic (355 nm) of Nd3+:YAG laser pulses (3 ns width), N-terminal amine groups of peptides instantly react with carbonyl groups of chlorobenzaldehyde or 2-hydroxy-5-methylisophthalaldehyde. Resultant peptides carrying with on-plate formed azomethine group (-C]N-) are simultaneously protonated and isolated as precursor ions for subsequent collision-activated dissociation. The mass shift with unique Cl isotopic signature unambiguously distinguishes b ions from y ions and other ions. This method does not need extensive sample preparation and is useful for those samples with limited quantities down to sub-picomole level in sub-microliter volumes. The efficiency was demonstrated with synthetic peptides and tryptic peptides of model proteins. It was found that 2-hydroxy-5-methylisophthalaldehyde provides improved yield for peptides containing lysine residues. Unknown proteins of human saliva and bovine milk as well as phosphopeptides have been identified.
关键词： Mass spectrometric de novo sequencing,N-terminal tag,2-Hydroxy-5-Methylisophthalaldehyde,Chlorobenzaldehyde,Photo induced dehydration reaction
更新于2025-09-16 10:30:52
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Protein-based microsphere biolasers fabricated by dehydration
摘要： Biolasers made of biological materials have attracted considerable research attention due to their biocompatibility and biodegradability, and have the potential for biosensing and biointegration. However, the current fabrication methods of biolasers suffer from several limitations, such as complicated processing, time-consuming and environmentally unfriendly nature. In this study, a novel approach with green processes for fabricating solid-state microsphere biolasers has been demonstrated. By dehydration via a modified Microglassificationt technology, dye-doped bovine serum albumin (BSA) droplets could be quickly (less than 10 minutes) and easily changed into solid microspheres with diameters ranging from 10 mm to 150 mm. The size of the microspheres could be effectively controlled by changing either the concentration of the BSA solution or the diameter of the initial droplets. The fabricated microspheres could act as efficient microlasers under an optical pulse excitation. A lasing threshold of 7.8 mJ mm?2 and a quality (Q) factor of about 1700 to 3100 were obtained. The size dependence of lasing characteristics was investigated, and the results showed a good agreement with whispering gallery mode (WGM) theory. Our findings contribute an effective technique for the fabrication of high-Q factor microlasers that may be potential for applications in biological and chemical sensors.
关键词： microspheres,dehydration,whispering gallery mode,bovine serum albumin,biolasers
更新于2025-09-16 10:30:52
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Optimization of melting parameters and minimizing OH content in SiO <sub/>2</sub> -B <sub/>2</sub> O <sub/>3</sub> -Na <sub/>2</sub> O-BaO glass system in microwave heating
摘要： This study investigates the optimization of melting process for the glass comprising SiO2‐B2O3‐Na2O‐BaO under microwave (MW) heating. Batches were melted at different temperatures in the range of 900‐1250°C to optimize melting condition. X‐ray diffraction suggests amorphous nature of samples melted above 1150°C. Optimization of melting time was carried out by varying soaking time (8‐60 minutes) at 1250°C. UV‐Vis‐NIR spectra reveal ~90% transmission over 300‐2000 nm wavelength range for glass melted at 1250°C. Optical microscopic images suggest that the bubble‐free glass can be produced at 1250°C for 1 hour melting in MW heating. MW heating also helps in reducing OH content in glass. However, OH concentration is found to increase with melting time. OH content could be minimized to 68.56 ppm in glass employing oxygen atmosphere melting, which prevents OH diffusion from atmosphere into the melt. Residual stresses are estimated to be less in MW heating than conventional heating. Maximum MW power was observed to be 1 kW with a total electrical power consumption of around 5 kWh. Also, total time needed to prepare the glass is around 2 hours. Thus, MW heating could be an alternate efficient tool in producing low OH content glass.
关键词： boro silicate glass,dehydration method,OH reduction process,microwave heating,optimization of glass melting process
更新于2025-09-10 09:29:36
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High–pressure electrical conductivity and Raman spectroscopy of chalcanthite
摘要： The phase transitions and dehydration of chalcanthite were investigated by electrical conductivity and Raman spectroscopy at 1.0–24.0 GPa and 293–673 K in a diamond anvil cell. At ambient temperature, two secondary phase transitions were observed according to discontinuous changes in the slope of Raman shifts, full width at half maximum and electrical conductivities at (cid:1)7.3 and (cid:1)10.3 GPa. The dehydration temperatures were determined by the splitting of Raman peaks and changes in electrical conductivity as (cid:1)350 and (cid:1)500 K at respective (cid:1)3.0 and (cid:1)6.0 GPa. A positive relationship for chalcanthite between dehydration temperature and pressure is established.
关键词： dehydration,chalcanthite,phase transition,Raman spectroscopy,electrical conductivity
更新于2025-09-09 09:28:46
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The impact of a hyaluronic acid-grafted layer on the surface properties of model silicone hydrogel contact lenses
摘要： The introduction of high oxygen transmissibility silicone hydrogel lenses ameliorated hypoxia-related complications, making them the most prescribed type of contact lens. Despite the progress made over the last two decades to improve their clinical performance, symptoms of ocular dryness and discomfort and a variety of adverse clinical events are still reported. Consequently, the rate of contact lens wear discontinuation has not been appreciably diminished by their introduction. Aiming to improve the interfacial interactions of silicone hydrogel contact lenses with the ocular surface, a biomimetic layer of the hydrophilic glycosaminoglycan hyaluronic acid (HA) (100 kDa), was covalently attached to the surface of model poly(2-hydroxyethyl methacrylate-co-3-methacryloxypropyl-tris-(trimethylsiloxy)silane) (pHEMA-co-TRIS) silicone hydrogel materials via UV-induced thiol-ene “click” chemistry. The surface structural changes after each modification step were studied by FTIR-ATR and XPS. Successful grafting of a homogenous HA layer to the surface of the model silicone hydrogels was confirmed by the consistent appearance of N (1s) and the significant decrease of the Si (2p) peaks, as determined by the low-resolution angle-resolved XPS. The HA-grafted surfaces demonstrated reduced contact angles, dehydration rate and nonspecific deposition of lysozyme and albumin, while maintaining their optical transparency (>90%). In vitro studies demonstrated that the HA-grafted pHEMA-co-TRIS materials did not show any toxicity to human corneal epithelial cells. These results suggest that surface immobilization of HA via thiol-ene “click” chemistry can be used as a promising surface treatment for silicone hydrogel contact lenses.
关键词： surface modification,dehydration,contact lenses,hyaluronic acid,MTT assay,thiol-ene chemistry,protein deposition,Silicone hydrogel
更新于2025-09-04 15:30:14