A disposable Ag–graphene sensor was developed for rapid and sensitive in-situ detection of polar antibiotics in water using electrophoretic preconcentration (EP) and surface-enhanced Raman ...spectroscopy (SERS). The Ag–graphene sensor was fabricated by depositing Ag–graphene nanocomposites synthesized through a facile one-pot method on the disposable screen-printed electrodes (SPEs) and characterized by transmission electron microscopy (TEM) and atomic force microscopy (AFM). SERS properties and detection applicability of the developed sensor were systematically investigated. It is shown that the polar antibiotics can be selectively adsorbed on the oppositely charged sensors after applying different potentials during the EP procedure, and the SERS signals of antibiotics with an effective amplification can be achieved with proper time of preconcentration. Moreover, the Ag–graphene sensor could facilitate the molecule adsorption through weak π–π interactions between graphene and antibiotics, further improving the sensitivity of SERS detection. Under the optimum EP conditions, the representative SERS spectra of a mixed solution containing four different antibiotics can be obtained within 10min, and each antibiotic is easily distinguished by its characteristic peaks with a sub-nM detection level. The results demonstrate that the proposed disposable Ag–graphene sensor based on EP–SERS can be used for rapid and sensitive in-situ detection of polar antibiotics in aqueous samples without a pre-separation step.
► We developed Ag–graphene sensors for polar antibiotics detection using EP–SERS. ► EP technique can selectively adsorb antibiotics to the SERS enhancement regions. ► The antibiotics adsorption can be accelerated through weak π–π interactions. ► The proposed method can detect antibiotics of sub-nM level in the mixed solution. ► Rapid and sensitive antibiotics detection can be performed in aqueous.
Microalgae have been emerging as an important source for the production of bioactive compounds. Marine diatoms can store high amounts of lipid and grow quite quickly. However, the genetic and ...biochemical characteristics of fatty acid biosynthesis in diatoms remain unclear. Glycerophospholipids are integral as structural and functional components of cellular membranes, as well as precursors of various lipid mediators. In addition, diacylglycerol acyltransferase (DGAT) is a key enzyme that catalyzes the last step of triacylglyceride (TAG) biosynthesis. However, a comprehensive sequence-structure and functional analysis of DGAT in diatoms is lacking. In this study, an isoform of diacylglycerol acyltransferase type 2 of the marine diatom Phaeodactylum tricornutum was characterized. Surprisingly, DGAT2 overexpression in P. tricornutum stimulated more oil bodies, and the neutral lipid content increased by 35%. The fatty acid composition showed a significant increase in the proportion of polyunsaturated fatty acids; in particular, EPA was increased by 76.2%. Moreover, the growth rate of transgenic microalgae remained similar, thereby maintaining a high biomass. Our results suggest that increased DGAT2 expression could alter fatty acid profile in the diatom, and the results thus represent a valuable strategy for polyunsaturated fatty acid production by genetic manipulation.
A coat of many colors: Plasmon resonance Rayleigh scattering (PRRS) spectroscopy is applied to the in‐situ monitoring of the NADH‐dependent growth of Au@Cu core–shell nanoparticles (NPs). The ...scattering signal of the AuNPs is red shifted when they are coated with Cu (see scheme). In conjunction with dark‐field microscopy, a colorimetric NADH‐dependent biosensor was constructed and tested to screen an anticancer drug affecting cell NADH metabolism.
Tyrosinase (TYR) is an essential oxidase that is responsible for the regulation of multiple physiological processes and diseases. Achieving the trace and reliable detection of TYR in complex ...biological samples is of great significance for the diagnosis of TYR-related diseases, but which faces a great challenge. In this study, we developed an ingenious and powerful method for the ultrasensitive detection of TYR by click reaction-combined dark-field microscopy. This method begins with the formation of cuprous ions (Cu+) based on the reduction of copper ions (Cu2+) by ascorbic acid (AA). Subsequently, the formed Cu+ can catalyze the crosslinking between azide- and alkyne-functionalized gold nanoparticles, causing a significant red-shift in the scattering spectrum. However, AA can chelate with TYR, which inhibits the generation of Cu+ and subsequent click reaction, thus achieving TYR-controlled scattering spectral shift. The proposed sensing platform shows a good linear detection range of 0.01–0.8 U/L with a low detection limit of 0.003 U/L, which is three orders of magnitude lower than the best performance of TYR sensing probes reported to date. Most importantly, the strategy has the ability to reliably and accurately detect TYR in serum sample, suggesting its potential clinical application in diagnosing TYR-related diseases. This visual sensing platform offers promising prospects for future research in enzymatic analysis and biomedical diagnostics.
This work developed an ingenious and powerful method for the ultrasensitive detection of tyrosinase by click reaction-combined dark-field microscopy, with a low detection limit of 0.003 U/L. Display omitted
•Click reaction-combined dark-field imaging platform is developed for ultrasensitive detection of tyrosinase.•The platform shows a detection limit of 0.003 U/L, which is three orders of magnitude lower than the currently methods.•The strategy has the ability to reliably and accurately detect tyrosinase in complrex serum sample.
Prosthetic valve endocarditis is a serious complication after heart valve replacement, accounting for about 20–30% of infective endocarditis (IE). Aspergillosis infection accounts for 25–30% of ...fungal endocarditis, and the mortality rate is 42–68%.
IE often has negative blood cultures and lacks fever, which makes diagnosis difficult and delays antifungal therapy. Our study reported a case of IE in a patient with
infection after aortic valve replacement. Ultra-multiplex polymerase chain reaction was used to identify
infection and guide treatment. The purpose of this study was to enhance the understanding of the management of patients with endocarditis infected by fungi after valve replacement regarding the early detection, timely intervention, and treatment of the fungal infection to reduce the risk of death and improve the long-term survival of patients.
Inorganic pyrophosphatase (PPase) plays significant roles in diverse pathophysiological processes, therefore, developing a reliable method to measure PPase activity is crucial for the early diagnosis ...of the related diseases. In this work, a novel platform with single-particle dark-field microscopy (DFM), consisting of core gold nanoparticles (AuNPs), satellite AuNPs, pyrophosphate ions (PPi), copper ions (Cu2+), and sodium ascorbate (NaAsc), is designed for the selective and sensitive analysis of PPase according to a click reaction. After the introduction of PPase, the coordination between PPi and Cu2+ can be destroyed by catalyzing the hydrolysis of PPi to release free Cu2+ which can be reduced by NaAsc to produce cuprous ions (Cu+). Then the formed Cu+ promotes the click reaction between azide-modified core AuNPs and alkynyl-modified satellite AuNPs to cause the significant redshift of the localized surface plasmon resonance (LSPR) spectra of core AuNPs. Thus, PPase can be ultra-sensitively detected with a low detection limit of 0.003 U/L in a wide linear range from 0.01 to 1 U/L. This click reaction-based DFM technique can also be used to assess PPase inhibition, which suggests that it has a lot of potential for both the screening of PPase inhibitors and the diagnosis of PPase-related disorders.
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•A single-particle dark-field scattering platform based on click reaction is developed for the detection of pyrophosphatase.•The platform shows a high selectivity to pyrophosphatase with a limit of detection of 3 mU/L in a wide linear range.•The proposed approach can perform well on the evaluation of pyrophosphatase inhibition.
We developed a novel enzyme-free amplified SERS immunoassay by combining silver nanoparticle (AgNP)-linked immunoreaction and SERS transduction for the detection of disease biomarkers. As a proof of ...concept, our method was successfully illustrated with the disease biomarker α-fetoprotein with the detection limit of 3.3 × 10-13 g mL-1 and a double-blind experiment consisting of tens of serum samples was performed to confirm its reliability.
Abstract
Artificially performing chemical reactions in living biosystems to attain various physiological aims remains an intriguing but very challenging task. In this study, the Schiff base reaction ...was conducted in cells using Sc(OTf)
3
as a catalyst, enabling the in situ synthesis of a hollow covalent organic polymer (HCOP) without external stimuli. The reversible Schiff base reaction mediated intracellular Oswald ripening endows the HCOP with a spherical, hollow porous structure and a large specific surface area. The intracellularly generated HCOP reduced cellular motility by restraining actin polymerization, which consequently induced mitochondrial deactivation, apoptosis, and necroptosis. The presented intracellular synthesis system inspired by the Schiff base reaction has strong potential to regulate cell fate and biological functions, opening up a new strategic possibility for intervening in cellular behavior.
Total joint arthroplasty is a common surgical procedure resulting in improved quality of life; however, a leading cause of surgery failure is infection. Periprosthetic joint infections often involve ...biofilms, making treatment challenging. The metabolic state of pathogens in the joint space and mechanism of their tolerance to antibiotics and host defenses are not well understood. Thus, there is a critical need for increased understanding of the physiological state of pathogens in the joint space for development of improved treatment strategies toward better patient outcomes. Here, we present a quantitative, untargeted NMR-based metabolomics strategy for Pseudomonas aeruginosa suspended culture and biofilm phenotypes grown in bovine synovial fluid as a model system. Significant differences in metabolic pathways were found between the suspended culture and biofilm phenotypes including creatine, glutathione, alanine, and choline metabolism and the tricarboxylic acid cycle. We also identified 21 unique metabolites with the presence of P. aeruginosa in synovial fluid and one uniquely present with the biofilm phenotype in synovial fluid. If translatable in vivo, these unique metabolite and pathway differences have the potential for further development to serve as targets for P. aeruginosa and biofilm control in synovial fluid.
A quantum-chemistry based protocol, termed MOSS-DFT, is presented for the prediction of 13C and 1H NMR chemical shifts of a wide range of organic molecules in aqueous solution, including metabolites. ...Molecular motif-specific linear scaling parameters are reported for five different density functional theory (DFT) methods (B97-2/pcS-1, B97-2/pcS-2, B97-2/pcS-3, B3LYP/pcS-2, and BLYP/pcS-2), which were applied to a large set of 176 metabolite molecules. The chemical shift root-mean-square deviations (RMSD) for the best method, B97-2/pcS-3, are 1.93 and 0.154 ppm for 13C and 1H chemical shifts, respectively. Excellent results have been obtained for chemical shifts of methyl and aromatic 13C and 1H that are not directly bonded to a heteroatom (O, N, S, or P) with RMSD values of 1.15/0.079 and 1.31/0.118 ppm, respectively. This study not only demonstrates how NMR chemical shift in aqueous environment can be improved over the commonly used global linear scaling approach, but also allows for motif-specific error estimates, which are useful for an improved chemical shift-based verification of metabolite candidates of metabolomics samples containing unknown components.
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