The oxidation of glucose and related compounds by glucose oxidase from Aspergillus Niger

Pazur J.H., Kleppe K.

Biochemistry. 1964, 3, 578-83.

Synthesis, Characterization, and Long-Term Stability of Hollow Polymer Nanocapsules with Nanometer-Thin Walls

Dergunov, S. A., K. Kesterson, et al. (2010).

Macromolecules (Washington, DC, U. S.) 43(18): 7785-7792.

Hollow polymer nanocapsules are produced by the polymn. within hydrophobic interior of lipid bilayers that act as temporary self-assembled scaffolds. Pore-forming templates are co-dissolved with monomers in the bilayers to create pores with controlled size and chem. environment. Polymn. was monitored with UV spectroscopy and dynamic light scattering. High-resoln. magic angle spinning NMR characterization provided detailed structural information about nanocapsules. Spherical shape was confirmed by electron microscopy. Medium-sized mols. can be entrapped within porous nanocapsules. No release of encapsulated mols. was obsd. within 240 days. 

Ultrasonic gene and drug delivery using eLiposomes

Marjan Javadi, William G. Pitt, Christopher M. Tracy, Jeffery R. Barrow, Barry M. Willardson, Jonathan M. Hartley, Naakaii H. Tsosie

Journal of Controlled Release 167 (2013) 92–100

eLiposomes are liposomes encapsulating emulsions and therapeutics for targeted delivery. By applying ultrasoundto eLiposomes, emulsion droplets can transform from liquid to gas and rupture the lipid bilayer of the eLiposome to release a drug or plasmid. In this study, perfluoropentane (PFC5) emulsions were encapsulated inside folated eLiposomes carrying a model drug (calcein) or a model GFP plasmid to examine the effects of a folate ligand, PFC5 emulsion and various ultrasonic acoustic parameters in drug delivery and gene transfection into HeLa cells.

Confocal microscopy was used to quantify drug delivery and the level of plasmid transfection into HeLa cells. The results showed that drug delivery or transfection was minimal without incorporation of internal PFC5 emulsions and folate ligand on the eLiposome surface. It was also shown that application of ultrasound greatly enhanced the drug delivery and plasmid transfection. Delivery of these therapeutics appears to be to the cytosol, indicating that the expansion of the emulsion droplets disrupted both the eLiposomes and the

endosomes.

Investigating Ligand−Receptor Interactions at Bilayer Surface Using Electronic Absorption Spectroscopy and Fluorescence Resonance Energy Transfer

Navneet Dogra, Xuelian Li, and Punit Kohli

dx.doi.org/10.1021/la300724z | Langmuir 2012, 28, 12989−12998

We investigate interactions between receptors and ligands at bilayer surface of polydiacetylene (PDA) liposomal nanoparticles using changes in electronic absorption spectroscopy and fluorescence resonance energy transfer (FRET). We study the effect of mode of linkage (covalent versus noncovalent) between the receptor and liposome bilayer. We also examine the effect of size-dependent interactions between liposome and analyte through electronic absorption and FRET responses. Glucose (receptor) molecules were either covalently or noncovalently attached at the bilayer of nanoparticles, and they provided selectivity for molecular interactions between glucose and glycoprotein ligands of E. coli. These interactions induced stress on conjugated PDA chain which resulted in changes (blue to red) in the absorption spectrum of PDA. The changes in electronic absorbance also led to changes in FRET efficiency between conjugated PDA chains (acceptor) and fluorophores (Sulphorhodamine-101) (donor) attached to the bilayer surface. Interestingly, we did not find significant differences in UV−vis and FRET responses for covalently and noncovalently bound glucose to liposomes following their interactions with E. coli. We attributed these results to close proximity of glucose receptor molecules to the liposome bilayer surface such that induced stress were similar in both the cases. We also found that PDA emission from direct excitation mechanism was ∼2−10 times larger than that of the FRET-based response. These differences in emission signals were attributed to three major reasons: nonspecific interactions between E. coli and liposomes, size differences between analyte and liposomes, and a much higher PDA concentration with respect to sulforhodamine (SR-101). We have proposed a model to explain our experimental observations. Our fundamental studies reported here will help in enhancing our knowledge regarding interactions involved between soft particles at molecular levels.

Polydiacetylene Liposomes Functionalized with Sialic Acid Bind and Colorimetrically Detect Influenza Virus

JACS:, 1995, 117, 829-830

Anke Reichert, Jon 0. Nagy, Wayne Spevak, and Deborah Charych*

Cell membranes are remarkable structures from a materials science point of view. These highly organized, self-assembled structures provide indispensable functions for cells such as molecular recognition, pumping, gating, energy conversion, and signal transduction.The design of “smart” materials based on membrane structures with specific functional properties is an emerging field of study! We have prepared synthetic, polymerizable liposomes that resemble the organization and functionalization of cell membranes and have employed them as simple colorimetric sensors. The liposomes were designed to specifically bind to influenza virus particles and, in addition, report the binding event by undergoing a visible color change. In effect, these molecular assemblies mimic cell surface molecular recognition as well as signal transduction.

Effect of inorganic positive ions on the adsorption of surfactant Triton X-100 at quartz/solution interface

Science in China Series B: Chemistry

October 2008, Volume 51, Issue 10, pp 918-927

YueHua Shao, 

Ying Li, 

XuLong Cao, 

DaZhong Shen, 

BaoMin Ma, 

HongYan Wang

The electrode-separated piezoelectric sensor (ESPS), an improved setup of quartz crystal microbalance (QCM), has been employed to investigate the adsorption behavior of nonionic surfactant Triton X-100 at the hydrophilic quartz-solution interface in mineralized water medium in situ, which contained CaCl₂ 0.01 mol·L⁻¹, MgCl₂ 0.01 mol·L⁻¹, NaCl 0.35 mol·L⁻¹. In a large scale of surfactant concentration, t effects of Ca²⁺, Mg²⁺ and Na⁺ on the adsorption isotherm and kinetics are obviously different. In aqueous solution containing NaCl only, adsorption of Triton X-100 on quartz-solution interface is promoted, both adsorption rate and adsorption amount increase. While in mineralized water medium, multivalent positive ions Ca²⁺ and Mg²⁺ are firmly adsorbed on quartz-solution interface, result in the increasing of adsorption rate and adsorption amount at low concentration of surfactant and the peculiar desorption of surfactant at high concentration of Triton X-100. The results got by solution depletion method are in good agreement with which obtained by ESPS. The “bridge” and “separate” effect of inorganic positive ions on the adsorption and desorption mechanism of Triton X-100 at the quartz-solution interface is discussed with molecular dynamics simulations (MD), flame atomic absorption spectrometry (FAAS) and atomic force microscopy (AFM) methods.

Synergistic Effect of Electric Field and Ultrasound on Transdermal Transport

Joseph Kost, 

Uwe Pliquett, 

Samir Mitragotri, 

Aye Yamamoto, 

Robert Langer, 

James Weaver

April 1996, Volume 13, Issue 4, pp 633-638