Nanqin Mei
Current Organizations / Institutes
The organizations/institutes from the scholar's latest article
Nanqin Mei has a total of 8 co-authors. Here are the top co-authors by number of shared publications:
- James H. Davis
Department of Physics, University of Guelph, Guelph, Ontario, Canada
1 shared publication - Morgan Robinson
Borch Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy Purdue University West Lafayette Indiana USA
1 shared publication - Ravi Gaikwad
Department of Physics & Astronomy, University of Waterloo, Waterloo, ON N2L 3G1, Canada
1 shared publication - Robert D. E. Henderson
Department of Medical Imaging, University of Saskatchewan, Saskatoon, Canada
1 shared publication - Shawn David Wettig
School of Pharmacy, University of Waterloo, 200 University Ave. W., Waterloo, ON N2L 3G1, Canada
1 shared publication - Yue Xu
Department of Physics & Astronomy, University of Waterloo, Waterloo, ON, N2L 3G1, Canada
1 shared publication
Latest Publications
- Open Access
- 26 March 2024
- Published by MDPI AG in Nanomaterials
- Vol. 14 (7) , 572
Nanoscale Structure of Lipid–Gemini Surfactant Mixed Monolayers Resolved with AFM and KPFM Microscopy
Drug delivery vehicles composed of lipids and gemini surfactants (GS) are promising in gene therapy. Tuning the composition and properties of the delivery vehicle is important for the efficient load and delivery of DNA fragments (genes). In this paper, we studied novel gene delivery systems composed of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), 1,2-dipalmitoyl-sn-3-phosphocholine (DPPC), and GS of the type N,N-bis(dimethylalkyl)--alkanediammonium dibromide at different ratios. The nanoscale properties of the mixed DOPC–DPPC–GS monolayers on the surface of the gene delivery system were studied using atomic force microscopy (AFM) and Kelvin probe force microscopy (KPFM). We demonstrate that lipid–GS mixed monolayers result in the formation of nanoscale domains that vary in size, height, and electrical surface potential. We show that the presence of GS can impart significant changes to the domain topography and electrical surface potential compared to monolayers composed of lipids alone.- 26 March 2024
- Published by MDPI AG in Nanomaterials
- Vol. 14 (7) , 572
Open AccessNanoscale Structure of Lipid–Gemini Surfactant Mixed Monolayers Resolved with AFM and KPFM Microscopy
Drug delivery vehicles composed of lipids and gemini surfactants (GS) are promising in gene therapy. Tuning the composition and properties of the delivery vehicle is important for the efficient load and delivery of DNA fragments (genes). In this paper, we studied novel gene delivery systems composed of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), 1,2-dipalmitoyl-sn-3-phosphocholine (DPPC), and GS of the type N,N-bis(dimethylalkyl)--alkanediammonium dibromide at different ratios. The nanoscale properties of the mixed DOPC–DPPC–GS monolayers on the surface of the gene delivery system were studied using atomic force microscopy (AFM) and Kelvin probe force microscopy (KPFM). We demonstrate that lipid–GS mixed monolayers result in the formation of nanoscale domains that vary in size, height, and electrical surface potential. We show that the presence of GS can impart significant changes to the domain topography and electrical surface potential compared to monolayers composed of lipids alone. - Open Access
Melatonin alters fluid phase co-existence in POPC/DPPC/cholesterol membranes
The structure and biophysical properties of lipid biomembranes are important for normal function of plasma and organelle membranes, which is essential for proper functioning of living cells. In Alzheimer’s disease (AD) the structure of neuronal membranes becomes compromised by the toxic effect of amyloid- β (A β ) protein which accumulates at neuron synapses, resulting in membrane perforation and dysfunction, oxidative stress and cell death. Melatonin is an important pineal gland hormone that has been shown to be protective against A β toxicity in cellular and animal studies, but the molecular mechanism of this protection is not well understood. It has been shown that melatonin can interact with model lipid membranes and alter the membrane biophysical properties, such as membrane molecular order and dynamics. This effect of melatonin has been previously studied in simple model bilayers with one or two lipid components, we consider a more complex ternary lipid mixture as our membrane model. In this study, we used 2 H-NMR to investigate the effect of melatonin on lipid phase behaviour of a three-component model lipid membranes composed of 1,2-dipalmitoyl- sn -glycero-3-phosphocholine (DPPC), 1-palmitoyl-2-oleoyl- sn -glycero-3-phosphocholine (POPC) and cholesterol. We used deuterium labelled palmitoyl- d 31 in POPC- d 31 and DPPC- d 62 separately, to probe the changes in hydrocarbon chain order as a function of temperature and varying concentrations of melatonin. We found that melatonin concentration influences phase separation in these ternary mixtures somewhat differently depending on whether POPC- d 31 or DPPC- d 62 was used. At 5 mol% melatonin we observed phase separation in samples with POPC- d 31 , but not with DPPC- d 62 . However, at 10 mol% melatonin phase separation was observed in both samples with either POPC- d 31 or DPPC- d 62 . These results indicate that melatonin can have a strong effect on membrane structure and physical properties, which may provide some clues to understanding how melatonin protects against A β . SIGNIFICANCE: Melatonin has been shown to be protective against A β pathology in animal and cellular studies. Although the mechanism of this protection is not well-understood, melatonin’s membrane-active properties may be important in this regard. In this work solid-state deuterium nuclear magnetic resonance was used to study the effect of melatonin on the POPC/DPPC/cholesterol model membranes. Specifically, we showed that melatonin modifies lipid hydrocarbon chain order to promote phase separation. This knowledge helps to explain the role of melatonin in lipid domain formation and may provide a deeper understanding of the mechanism of melatonin neuroprotection in AD.
Open AccessMelatonin alters fluid phase co-existence in POPC/DPPC/cholesterol membranes
The structure and biophysical properties of lipid biomembranes are important for normal function of plasma and organelle membranes, which is essential for proper functioning of living cells. In Alzheimer’s disease (AD) the structure of neuronal membranes becomes compromised by the toxic effect of amyloid- β (A β ) protein which accumulates at neuron synapses, resulting in membrane perforation and dysfunction, oxidative stress and cell death. Melatonin is an important pineal gland hormone that has been shown to be protective against A β toxicity in cellular and animal studies, but the molecular mechanism of this protection is not well understood. It has been shown that melatonin can interact with model lipid membranes and alter the membrane biophysical properties, such as membrane molecular order and dynamics. This effect of melatonin has been previously studied in simple model bilayers with one or two lipid components, we consider a more complex ternary lipid mixture as our membrane model. In this study, we used 2 H-NMR to investigate the effect of melatonin on lipid phase behaviour of a three-component model lipid membranes composed of 1,2-dipalmitoyl- sn -glycero-3-phosphocholine (DPPC), 1-palmitoyl-2-oleoyl- sn -glycero-3-phosphocholine (POPC) and cholesterol. We used deuterium labelled palmitoyl- d 31 in POPC- d 31 and DPPC- d 62 separately, to probe the changes in hydrocarbon chain order as a function of temperature and varying concentrations of melatonin. We found that melatonin concentration influences phase separation in these ternary mixtures somewhat differently depending on whether POPC- d 31 or DPPC- d 62 was used. At 5 mol% melatonin we observed phase separation in samples with POPC- d 31 , but not with DPPC- d 62 . However, at 10 mol% melatonin phase separation was observed in both samples with either POPC- d 31 or DPPC- d 62 . These results indicate that melatonin can have a strong effect on membrane structure and physical properties, which may provide some clues to understanding how melatonin protects against A β . SIGNIFICANCE: Melatonin has been shown to be protective against A β pathology in animal and cellular studies. Although the mechanism of this protection is not well-understood, melatonin’s membrane-active properties may be important in this regard. In this work solid-state deuterium nuclear magnetic resonance was used to study the effect of melatonin on the POPC/DPPC/cholesterol model membranes. Specifically, we showed that melatonin modifies lipid hydrocarbon chain order to promote phase separation. This knowledge helps to explain the role of melatonin in lipid domain formation and may provide a deeper understanding of the mechanism of melatonin neuroprotection in AD.