Lipid phase dependent distinct emission behaviour of hydrophobic carbon dots: C-dots based membrane probe

2021 ◽  
Author(s):  
Soumya De ◽  
Avijit Maity ◽  
Debanjan Bagchi ◽  
Anjan Chakraborty
Keyword(s):  
Carbon Dots ◽  
Lipid Membrane ◽  
Blue Emission ◽  
Lipid Phase ◽  
Membrane Probe ◽  
Disordered Phase

We observe an unique distinct emission behaviour of hydrophobic carbon dots (H-CDs) embedded within the ordered and the disordered phase of the lipid membrane. The H-CDs exhibit the blue emission...

scholarly journals Synthesis and Characterization of a Novel Green Cationic Polyfluorene and Its Potential Use as a Fluorescent Membrane Probe

Polymers ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 938 ◽  
Author(s):  
Rebeca Vázquez-Guilló ◽  
María Martínez-Tomé ◽  
Zehra Kahveci ◽  
Ivan Torres ◽  
Alberto Falco ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Membrane Surface ◽  
Aqueous Media ◽  
Coupling Reaction ◽  
Model Membranes ◽  
Lipid Phase ◽  
Fluorescent Properties ◽  
Membrane Probe ◽  
Fluorescence Efficiency ◽  
Potential Use

In the present work, we have synthesized a novel green-emitter conjugated polyelectrolyte Copoly-{[9,9-bis(6′-N,N,N-trimethylammonium)hexyl]-2,7-(fluorene)-alt-4,7-(2-(phenyl) benzo[d] [1,2,3] triazole)} bromide (HTMA-PFBT) by microwave-assisted Suzuki coupling reaction. Its fluorescent properties have been studied in aqueous media and in presence of model membranes of different composition, in order to explore its ability to be used as a green fluorescent membrane probe. The polyelectrolyte was bound with high affinity to the membrane surface, where it exhibited high fluorescence efficiency and stability. HTMA-PFBT showed lower affinity to zwitterionic membranes as compared to anionic ones, as well as a more external location, near the membrane-aqueous interface. Fluorescence microscopy studies confirmed the interaction of HTMA-PFBT with the model membranes, labelling the lipid bilayer without perturbing its morphology and showing a clear preference towards anionic systems. In addition, the polyelectrolyte was able to label the membrane of bacteria and living mammalian cells, separately. Finally, we explored if the polyelectrolyte can function also as a sensitive probe able of detecting lipid-phase transitions. All these results suggest the potential use of HTMA-PFBT as a green membrane marker for bioimaging and selective recognition of bacteria cell over mammalian ones and as a tool to monitor changes in physical state of lipid membranes.

scholarly journals Nitrogen-induced shift of photoluminescence from green to blue emission for xylose-derived carbon dots

Nano Express ◽  
2020 ◽  
Vol 1 (2) ◽  
pp. 020018
Author(s):  
Shanshan Wang ◽  
Dong-Sheng Yang ◽  
Fuqian Yang
Keyword(s):  
Carbon Dots ◽  
Blue Emission

scholarly journals Melittin Induces Local Order Changes in Artificial and Biological Membranes as Revealed by Spectral Analysis of Laurdan Fluorescence

Toxins ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 705
Author(s):  
Bogdan Zorilă ◽  
George Necula ◽  
Mihai Radu ◽  
Mihaela Bacalum
Keyword(s):  
Lipid Membranes ◽  
Lipid Membrane ◽  
Local Order ◽  
Generalized Polarization ◽  
Membrane Probe ◽  
Area Per Lipid ◽  
The Difference ◽  
Log Normal ◽  
Laurdan Fluorescence ◽  
Natural Lipid

Antimicrobial peptides (AMPs) are a class of molecules widely used in applications on eukaryotic and prokaryotic cells. Independent of the peptide target, all of them need to first pass or interact with the plasma membrane of the cells. In order to have a better image of the peptide action mechanism with respect to the particular features of the membrane it is necessary to better understand the changes induced by AMPs in the membranes. Laurdan, a lipid membrane probe sensitive to polarity changes in the environment, is used in this study for assessing changes induced by melittin, a well-known peptide, both in model and natural lipid membranes. More importantly, we showed that generalized polarization (GP) values are not always efficient or sufficient to properly characterize the changes in the membrane. We proved that a better method to investigate these changes is to use the previously described log-normal deconvolution allowing us to infer other parameters: the difference between the relative areas of elementary peak (ΔSr), and the ratio of elementary peaks areas (Rs). Melittin induced a slight decrease in local membrane fluidity in homogeneous lipid membranes. The addition of cholesterol stabilizes the membrane more in the presence of melittin. An opposite response was observed in the case of heterogeneous lipid membranes in cells, the local order of lipids being diminished. RS proved to be the most sensitive parameter characterizing the local membrane order, allowing us to distinguish among the responses to melittin of both classes of membrane we investigated (liposomes and cellular membranes). Molecular simulation of the melittin pore in homogeneous lipid bilayer suggests that lipids are more closely packed in the proximity of the melittin pore (a smaller area per lipid), supporting the experimental observation.

Exploring the Biophysical Interaction of 3-Pentadecylphenol with Head Group Region of Lipid Membrane using Fisetin as an Interfacial Membrane Probe

2021 ◽  
Author(s):  
Jhili Mishra ◽  
Ashok Kumar Mishra ◽  
Jitendriya Swain
Keyword(s):  
Lipid Membrane ◽  
Molecular Level ◽  
Industrial Applications ◽  
Head Group ◽  
Membrane Modification ◽  
Natural Sources ◽  
Membrane Probe ◽  
Interfacial Membrane

3-Pentadecylphenol (PDP) is a phenolic lipid easily available from natural sources. This compound has different pharmacological, biological and industrial applications. A molecular level understanding on the membrane modification properties of...

scholarly journals Ratiometric fluorescent test paper based on silicon nanocrystals and carbon dots for sensitive determination of mercuric ions

2018 ◽  
Vol 5 (6) ◽  
pp. 171922 ◽  
Author(s):  
Xinfeng Guo ◽  
Cui Liu ◽  
Nian Li ◽  
Shudong Zhang ◽  
Zhenyang Wang
Keyword(s):  
Carbon Dots ◽  
Silicon Nanocrystals ◽  
Fluorescence Probe ◽  
Blue Emission ◽  
Cost Effective ◽  
Test Paper ◽  
Internal Reference ◽  
Naked Eye ◽  
Wide Range

Classical dye absorption-based pH test papers are widely used to measure the degree of acidity of media for quantification or semi-quantification by the observation of the naked eye on the variation of colour. However, it remains a challenging task to extend portable and cheap methods to a wide range of analytes for accurate quantification. Here, we report a dosage-sensitive test paper for the assay of mercury ions (Hg 2+ ) with wide colour evolution. The ratiometric fluorescent probe was prepared by mixing blue-emission silicon nanocrystals (Si NCs) and red-emission carbon dots (r-CDs). The Si NCs serve as the reaction site and the r-CDs as the internal reference. Upon the addition of Hg 2+ , the blue fluorescence of the Si NCs was quenched, while the red fluorescence of the r-CDs remained constant, resulting in the consecutive fluorescence colour changes from blue to orange red. The probe demonstrates high selectivity and sensitivity of the visualization assay of Hg 2+ with a detection limit of 7.63 nM. Moreover, we printed the ratiometric fluorescence probe result onto a piece of filter paper to prepare a test paper, which represents an on-site, sensitive, rapid and cost-effective method for the visual determination of Hg 2+ by the naked eye.

scholarly journals Mimicking the Mammalian Plasma Membrane: An Overview of Lipid Membrane Models for Biophysical Studies

Biomimetics ◽  
2020 ◽  
Vol 6 (1) ◽  
pp. 3
Author(s):  
Alessandra Luchini ◽  
Giuseppe Vitiello
Keyword(s):  
Plasma Membrane ◽  
Lipid Bilayers ◽  
Lipid Membranes ◽  
Cell Membranes ◽  
Lipid Membrane ◽  
Lipid Phase ◽  
Chemical Information ◽  
Lipid Species ◽  
Membrane Models ◽  
The Impact

Cell membranes are very complex biological systems including a large variety of lipids and proteins. Therefore, they are difficult to extract and directly investigate with biophysical methods. For many decades, the characterization of simpler biomimetic lipid membranes, which contain only a few lipid species, provided important physico-chemical information on the most abundant lipid species in cell membranes. These studies described physical and chemical properties that are most likely similar to those of real cell membranes. Indeed, biomimetic lipid membranes can be easily prepared in the lab and are compatible with multiple biophysical techniques. Lipid phase transitions, the bilayer structure, the impact of cholesterol on the structure and dynamics of lipid bilayers, and the selective recognition of target lipids by proteins, peptides, and drugs are all examples of the detailed information about cell membranes obtained by the investigation of biomimetic lipid membranes. This review focuses specifically on the advances that were achieved during the last decade in the field of biomimetic lipid membranes mimicking the mammalian plasma membrane. In particular, we provide a description of the most common types of lipid membrane models used for biophysical characterization, i.e., lipid membranes in solution and on surfaces, as well as recent examples of their applications for the investigation of protein-lipid and drug-lipid interactions. Altogether, promising directions for future developments of biomimetic lipid membranes are the further implementation of natural lipid mixtures for the development of more biologically relevant lipid membranes, as well as the development of sample preparation protocols that enable the incorporation of membrane proteins in the biomimetic lipid membranes.

scholarly journals Carboxyl-Rich Carbon Dots as Highly Selective and Sensitive Fluorescent Sensor for Detection of Fe3+ in Water and Lactoferrin

Polymers ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 4317
Author(s):  
Xinxin Wang ◽  
Yanan Zhao ◽  
Ting Wang ◽  
Yan Liang ◽  
Xiangzhong Zhao ◽  
...  
Keyword(s):  
Carbon Dots ◽  
Density Functional ◽  
Limit Of Detection ◽  
Fluorescent Sensor ◽  
Low Cost ◽  
Hydrothermal Process ◽  
Blue Emission ◽  
Disease Diagnosis ◽  
Obvious Effect ◽  
Physiological Processes

As lactoferrin (LF) plays an essential role in physiological processes, the detection of LF has attracted increasing attention in the field of disease diagnosis. However, most current methods require expensive equipment, laborious pretreatment, and long processing time. In this work, carboxyl-rich carbon dots (COOH-CDs) were facilely prepared through a one-step, low-cost hydrothermal process with tartaric acid as the precursor. The COOH-CDs had abundant carboxyl on the surface and showed strong blue emission. Moreover, COOH-CDs were used as a fluorescent sensor toward Fe3+ and showed high selectivity for Fe3+ with the limit of detection (LoD) of 3.18 nM. Density functional theory (DFT) calculations were performed to reveal the mechanism of excellent performance for Fe3+ detection. Meanwhile, COOH-CDs showed no obvious effect on lactobacillus plantarum growth, which means that COOH-CDs have good biocompatibility. Due to the nontoxicity and excellent detection performance for Fe3+, COOH-CDs were employed as a fluorescent sensor toward LF and showed satisfying performance with an LoD of 0.776 µg/mL, which was better than those of the other methods.

scholarly journals The orientation of a membrane probe from structural analysis by enhanced Raman scattering

2019 ◽  
Author(s):  
Hannah J. Hughes ◽  
Steven M. E. Demers ◽  
Aobo Zhang ◽  
Jason H. Hafner
Keyword(s):  
Structural Analysis ◽  
Raman Scattering ◽  
Molecular Mechanisms ◽  
Electrical Potential ◽  
Polar Angle ◽  
Optical Measurements ◽  
Membrane Properties ◽  
Lipid Phase ◽  
Membrane Probe ◽  
Enhanced Raman Scattering

ABSTRACTSmall fluorescent molecules are widely used as probes of biomembranes. Different probes optically indicate membrane properties such as the lipid phase, thickness, viscosity, and electrical potential. The detailed molecular mechanisms behind probe signals are not well understood, in part due to the lack of tools to determine probe position and orientation in the membrane. Optical measurements on aligned biomembranes and lipid bilayers provide some degree of orientational information based on anisotropy in absorption, fluorescence, or nonlinear optical properties. These methods typically find the polar tilt angle between the membrane normal and the long axis of the molecule. Here we show that solution-phase surface enhanced Raman scattering (SERS) spectra of lipid membranes on gold nanorods can be used to determine molecular orientation of molecules within the membrane. The voltage sensitive dye 4-(2-(6-(dibutylamino)-2-naphthalenyl)ethenyl)-1-(3-sulfopropyl)-hydroxide, known as di-4-ANEPPS, is studied. Through the analysis of several peaks in the SERS spectrum, the polar angle from the membrane normal is found to be 63°, and the roll angle around the long axis of the molecule to be 305° from the original orientation. This structural analysis method could help elucidate the meaning of fluorescent membrane probe signals, and how they are affected by different lipid compositions.

scholarly journals Evaluation of the Environmental Impact and Efficiency of N-Doping Strategies in the Synthesis of Carbon Dots

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 504 ◽  
Author(s):  
Christé ◽  
Esteves da Silva ◽  
Pinto da Silva
Keyword(s):  
Carbon Dots ◽  
Organic Molecules ◽  
Blue Emission ◽  
Xps Analysis ◽  
Small Organic Molecules ◽  
Microwave Assisted ◽  
N Doping ◽  
Synthesis Routes ◽  
The One ◽  
Synthesis Yield

The efficiency and associated environmental impacts of different N-doping strategies of carbon dots (CDs) were evaluated. More specifically, N-doped CDs were prepared from citric acid via two main synthesis routes: Microwave-assisted hydrothermal treatment with addition of N-containing small organic molecules (urea and ethylenediamine (EDA)); and microwave-assisted solvothermal treatment in N-containing organic solvents (n,n-dimethylformamide (DMF), acetonitrile and pyridine). These syntheses produced CDs with similar blue emission. However, XPS analysis revealed that CDs synthesized via both hydrothermal routes presented a better N-doping efficiency (~15 at.%) than all three solvothermal-based strategies (0.6–7 at.%). However, from the former two hydrothermal strategies, only the one involving EDA as a nitrogen-source provided a non-negligible synthesis yield, which indicates that this should be the preferred strategy. This conclusion was supported by a subsequent life cycle assessment (LCA) study, which revealed that this strategy is clearly the most sustainable one from all five studied synthesis routes.

scholarly journals Hypothesis of Lipid-Phase-Continuity Proton Transfer for Aerobic ATP Synthesis

2013 ◽  
Vol 33 (12) ◽  
pp. 1838-1842 ◽  
Author(s):  
Alessandro M Morelli ◽  
Silvia Ravera ◽  
Daniela Calzia ◽  
Isabella Panfoli
Keyword(s):  
Proton Transfer ◽  
Lipid Membrane ◽  
Atp Synthesis ◽  
Active Role ◽  
Lipid Phase ◽  
Mechanical Coupling ◽  
Sources And Sinks ◽  
Evolution Of Life ◽  
Grotthus Mechanism ◽  
Supramolecular Aggregates

The basic processes harvesting chemical energy for life are driven by proton (H+) movements. These are accomplished by the mitochondrial redox complex V, integral membrane supramolecular aggregates, whose structure has recently been described by advanced studies. These did not identify classical aqueous pores. It was proposed that H+ transfer for oxidative phosphorylation (OXPHOS) does not occur between aqueous sources and sinks, where an energy barrier would be insurmountable. This suggests a novel hypothesis for the proton transfer. A lipid-phase-continuity H+ transfer is proposed in which H+ are always bound to phospholipid heads and cardiolipin, according to Mitchell's hypothesis of asymmetric vectorial H+ diffusion. A phase separation is proposed among the proton flow, following an intramembrane pathway, and the ATP synthesis, occurring in the aqueous phase. This view reminiscent of Grotthus mechanism would better account for the distance among the Fo and F1 moieties of FoF1–ATP synthase, for its mechanical coupling, as well as the necessity of a lipid membrane. A unique active role for lipids in the evolution of life can be envisaged. Interestingly, this view would also be consistent with the evidence of an OXPHOS outside mitochondria also found in non-vesicular membranes, housing the redox complexes.

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