查看更多>>摘要：Extracting molecular level label-free information from complex biological processes for a range of purposes including disease diagnosis and microbial identification and discrimination is always a challenging task. This is mostly due to lack of a technique providing rich molecular information with a high spatial and temporal resolution properties. Two surface-enhanced vibrational spectroscopic (SEVS) techniques, surface-enhanced Raman scattering (SERS) and surface-enhanced infrared absorption spectroscopy (SEIRAS), are recently attracting considerable attention to study biosystems at an interface since they can satisfy these requirements to a certain level by providing rich intrinsic molecular information from molecules and molecular systems in a close proximity of nanostructured noble metal surfaces. In this study, these two surface-enhanced vibrational spectroscopic techniques are comparatively evaluated for the discrimination and identification of Candida albicans (C. albicans), Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) by paying attention to the source of the observed spectral pattern. The citrate-reduced colloidal silver nanoparticles (AgNPs) were used as substrates. The results show that the SEIRAS provides very rich molecular information about the biomolecular species adsorbed onto AgNPs similar to the case of SERS. The discrimination power of SEIRAS is much improved compared to FTIR demonstrated by PCA analysis. This study suggests that SEIRAS can be a potential technique for microbial analysis. (C) 2021 Elsevier B.V. All rights reserved.
Kalcec, NikolinaPeranic, NikolinaBarbir, RineaHall, Christopher R....
13页
查看更多>>摘要：Nano-drug delivery systems may potentially overcome current challenges in the treatment of Parkinson's disease (PD) by enabling targeted delivery and more efficient blood-brain penetration ability. This study investigates novel gold nanoparticles (AuNPs) to be used as delivery systems for L-DOPA and dopamine by considering their binding capabilities in the presence and absence of a model protein, bovine serum albumin (BSA). Four different AuNPs were prepared by surface functionalization with polyethylene glycol (PEG), 1-adamantylamine (Ad), 1-adamantylglycine (AdGly), and peptidoglycan monomer (PGM). Fluorescence and UV-Vis measurements demonstrated the strongest binding affinity and L-DOPA/ dopamine loading efficiency for PGM-functionalized AuNPs with negligible impact of the serum protein presence. Thermodynamic analysis revealed a spontaneous binding process between L-DOPA or dopamine and AuNPs that predominantly occurred through van der Waals interactions/hydrogen bonds or electrostatic interactions. These results represent PGM-functionalized AuNPs as the most efficient at LDOPA and dopamine binding with a potential to become a drug-delivery system for neurodegenerative diseases. Detailed investigation of L-DOPA/dopamine interactions with different AuNPs was described here for the first time. Moreover, this study highlights a cost- and time-effective methodology for evaluating drug binding to nanomaterials. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：In this work, immune modified graphene quantum dot (GQD) and semiconductor quantum dot (SQD) with blue and red emission respectively were synthesized to assemble a dual-QDs ratios fluorescent probe, which could be efficient used for insulin determination. There may be the dynamic equilibrium of forster resonance energy transfer (FRET) and aggregation-induced emission (AIE) in the internal of the probe, thus emitted special dual fluorescent lights. However, this sate of probe was cleaved upon exposure to target insulin, resulting in changing of the dual fluorescent lights. The resulting ratios response can be correlated quantitatively to the concentration of insulin, and was found to have a detection limit (as low as 0.045 ng mL(-1)) and rapid response time (as short as 5 min). It has been preliminarily used for ratiometric sensing of insulin in biological samples and exhibited consistency of the insulin detected results and higher stability compared with conventional ELISA. Therefore, this sensitive, rapid and stable detection system has great potential for next generation of the bioassay platform for clinical diagnosis and other applications. (C) 2021 Elsevier B.V. All rights reserved.
Ullah, ZakirYadav, RohitashGupta, NitinChurchill, David G....
8页
查看更多>>摘要：Drug delivery devices are an effective way to minimize anticancer drug toxicity and nanostructures are used in the targeted drug delivery. In the present work, adsorption and interaction behavior of 4-(dime thylaminodiazenyl)-1H-imidazole-5-carboxamide (DAIC) with nano complexes (graphene, fullerene and fullerene like metal cages) are reported theoretically. From the reactivity studies, the electrophilicity index of DAIC-nanoclusters are increasing and this gives the bioactivity of the nanocluster systems. Adsorption energy is highest in the case of AlP and lowest in the case of BP clusters. Mulliken charge distribution of all systems is an evidence for chemical enhancement. DAIC adsorption over nanocages causes changes in electronic properties resulting in chemical enhancement and variation in Raman spectra which suggests that nanocages could be a good candidate for DAIC detection. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：A Schiff-based aggregation induced emission (ALE) fluorescent probe with excited intramolecular proton transfer (ESIPT) mechanism was synthesized by grafting 2-hydrazinobenzothiazole onto 2,6-diformyl-4-methylphenol. The probe recognizes Zn2+ selectively and sensitively, accompanied by a significant fluorescence emission increasement change from light yellow-green to strong green. Additionally, a stabilization time of at least 30 min was kept in the recognition process. Besides, a linear relationship was observed between the concentration of Zn2+ and the fluorescence intensity at 525 nm (0.05-10 mu M). And thus, the probe can detect Zn2+ quantitatively in aqueous solution with a low detection limit of 1.9 x 10(-8) M. Based on the ALE property and the selective recognition of Zn2+, SCH was strategically loaded on the filter paper to develop a novel paper-based indicator for on-site and high-efficiency detection of Zn2+. The results showed that the paper-based indicator could be conveniently applied to the visual inspection of Zn2+ as expected and SCH in the paper-based indicators fortunately exhibited a better stability. Furthermore, our comprehensive application evaluations have confirmed that SCH was capable of detecting Zn2+ in real water samples and imaging Zn2+ in living cells roundly. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Cobalt as a transition metal ion is a biologically essential trace element, and plays an important role in various biological systems. The silicon nanoparticles (SiNPs) / gold nanoparticles (AuNPs) composite as a simple and efficient fluorescent probe was developed to detect Co2+ and vitamin B-12( )(VB12) based on the selective aggregation and inner filter effect (IFE). The green-emitting SiNPs were synthesized by one-pot hydrothermal method, and the AuNPs were synthesized and modified with thioglycolic acid and cetyltrimethylammonium bromide. The fluorescent probe was fabricated by simple mixing the SiNPs and AuNPs together. In the presence of Co2+/VB12, AuNPs are selectively aggregated, which results in the enhancement of the local surface plasmon resonance absorption centered at 520 nm and the green fluorescence of SiNPs is significantly quenched via IFE. The fluorescence quenching efficiency of the probe is linearly proportional to the concentration of Co' in the range of 0.1-80 mu M with a low detection limit of 60 nM, which is far lower than the guideline value of Co2+ in drinking water (1.7 mu M). For vitamin B-12 (VB12), its linear relationship is in the range of 0.1-100 mu M, and the limit of detection is 69 nM. Furthermore, the proposed method shows good selectivity for the detection of Co2+ and VB12, and does not need sophisticated pretreatment, only through simple filter. It has been applied in actual environmental water samples and drug tablets with satisfactory results. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Albumin is the most abundant serum protein that transports hormones, free fatty acids, bilirubin, various ions, and drugs. The current study investigated the potential application of laser-induced fluorescence (LIF) in clinical analysis of human serum albumin (HSA) as a biomarker of liver and kidney disease. The excitation wavelength and HSA concentrations were systematically varied, and the LIF spectrum was recorded, in order to construct a standard calibration curve. Over a wide range of excitation wavelengths, excitation at 350 nm showed the maximum fluorescence emission centered at 500 nm. We compared the determination of certain concentrations of HSA using both LIF and conventional laboratory assays. The LIF technique proved to be highly accurate and efficient. It may be concluded that femtosecond LIF provides a new, easy, very sensitive, precise, and direct method of detecting albumin in various biological samples. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：In this work, a bifunctional peptide-based fluorescent probe L containing a tetrapeptide scaffold (Pro-Gly-His-Trp-NH2) and a dansyl group was synthesized using solid phase peptide synthesis (SPPS) technology. As designed, L, based on a FRET mechanism, exhibited high selectivity, excellent ratiometric signals, and fast response to Zn2+ in aqueous solutions at an excitation wavelength of 280 nm. In addition, when excited at 320 nm, L exhibited a fluorescent ''turn-on" response towards Zn2+ based on PET mechanism. More importantly, the stoichiometry of L and Zn2+ was determined to be 2:1 by fluorescent titration, Job's plot method, and ESI-MS spectrometry. The association constant for Zn2+ ions was determined to be 6.26 - 108 M-2, while the limit of detection (LOD) of L was estimated as 5.43 nM, which is a much lower value than WHO and EPA guidelines for drinking water. Moreover, L was successfully applied to detect both Zn2+ and Cu2+ in living cells due to good biocompatibility and excellent low toxicity. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Photoconvertible fluorophores are important for a myriad of applications in chemistry and biology. Here, we spectrally resolve and quantify individual photophysical information of a dual-emitting photoconvertible fluorophore by fluorescence spectroscopy and multivariate curve resolution-alternate least square techniques. We found that the reactant fluorophore, which shows a weak locally excited (LE) emission and a dominant intramolecular charge transfer (ICT) emission, also exhibits an intermolecular charge transfer emission. The ICT emission bands of both the reactant and product fluorophores are originated from their respective LE states. The reactant fluorophore is a mixture of its different ground state conformers. Higher yields of photoconversion of the yellow-emitting reactant fluorophore are achieved via a visible light photoreaction, leading to formation of pure white light at an intermediate photoreaction time. These findings together help us to glean new photophysical and photochemical insights into the photoreaction of a dual-emitting photoconvertible fluorophore. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Infrared spectroscopy is a powerful tool for the understanding of molecular structure and function of polypeptides. Theoretical interpretation of IR spectra relies on ab initio calculations may be very costly in computational resources. Herein, we developed a neural network (NN) modeling protocol to evaluate a model dipeptide's backbone amide-I spectra. DFT calculations were performed for the amide-I vibrational motions and structural parameters of alanine dipeptide (ALAD) conformers in different micro environments ranging from polar to non-polar ones. The obtained backbone dihedrals, C = O bond lengths and amide-I frequencies of ALAD were gather together for NN architecture. The applications of built NN protocols for the prediction of amide-I frequencies of ALAD in other solvation conditions are quite satisfactory with much less computational cost comparing with electronic structure calculations. The results show that this cost-effective way enables us to decipher the polypeptide's dynamic secondary structures and biological functions with their backbone vibrational probes. (c) 2021 Elsevier B.V. All rights reserved.
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