Measuring Sedimentation, Diffusion, and Molecular Weights of Small Molecules by Direct Fitting of Sedimentation Velocity Concentration Profiles

1994 ◽  
pp. 156-170 ◽  
Author(s):  
John S. Philo
Keyword(s):  
Small Molecules ◽  
Sedimentation Velocity ◽  
Concentration Profiles ◽  
Molecular Weights

Scattering of light by multi-component systems

1963 ◽  
Vol 275 (1361) ◽  
pp. 271-283 ◽  
Keyword(s):  
Experimental Data ◽  
Small Molecules ◽  
Isothermal Compressibility ◽  
Carbon Disulphide ◽  
Molecular Weights ◽  
Pure Solvent ◽  
Component Systems ◽  
Scattering Light ◽  
Solvent Molecules ◽  
Small Solute

The expression usually quoted for the extinction of light transmitted by a solution (the turbidity) is ‘Einstein’s scattering formula’ which contains two terms. It is shown here that in addition to these two terms which are due respectively to the excess scattering of the solute over the solvent and (essentially) to the pure solvent, there is a third term depending both on a natural 'excess' polarizability of the solute and on the polarizability of the solvent. This term is unlikely to alter estimates of molecular weights from the turbidity by more than a few tens of molecular weight units so is important only for solutions of small molecules. The expected corrections agree very well indeed with published experimental data on carbon disulphide in carbon tetrachloride and diethyl ether in benzene, and thereby offer some experimental evidence on the unresolved question of the validity of a factor of refractive index in the theoretical expressions for turbidities. The corrected formula may make it possible to investigate by light scattering the dependence of the isothermal compressibility of solutions on the concentration of solute. The concept of an ‘excess’ molecular polarizability for solute molecules in a solvent and scattering light is justified for small solute and solvent molecules.

Multiple scattering and the scattering of light by large or small molecules in solution

1965 ◽  
Vol 258 (1090) ◽  
pp. 387-420 ◽  
Keyword(s):  
Light Scattering ◽  
Small Molecules ◽  
Multiple Scattering ◽  
Additional Term ◽  
Molecular Size ◽  
Internal Field ◽  
Single Scattering ◽  
Particle Correlation ◽  
Molecular Weights ◽  
Two Component

The scattering equations for two-component fluids are formulated so that individual scattering processes take place in vacuo. A gauge transformation is made which transforms these processes to ones taking place in a medium of refractive index m. Certain previously controversial factors apparently associated with the internal field are thereby isolated and shown to be multiple scattering terms. The formulae for the scattered intensity and turbidity of a two-component fluid of small molecules are calculated by an entirely molecular argument; they agree with the forms usually quoted as Einstein’s formulae except that the additional term reported previously is confirmed. It is conjected that a very precise identity exists between the phenomenological and molecular treatments of scattering when multiple scattering is properly included. It is shown that the concept of an excess molecular polarizability in a two-component system of small molecules is valid only up to an approximation of single scattering: but the concept of excess scattering remains valid in the multiple scattering theory of such systems. It is also shown that without additional assumptions both these concepts cease to be valid even in the single scattering approximation when the solute molecules are large. These assumptions amount to a ‘uniform distribution’ (in a sense here specified) of the solvent round the solute in regions of radius of the order of iA: they can be interpreted as hydration (or solvation) conditions. From a crude model of a macromolecular solution it is suggested that the Debye corrections which derive from a finite molecular size to estimates of molecular weights determined by light scattering, could be in error by as much as 100% (~ 5% of molecular weights) or perhaps even more: estimates of molecular size by dissymmetry can also be in similar error. For a given solute, both these and the molecular weight corrections should vary from solvent to solvent. As this has not been reported experimentally, solutions of large molecules may satisfy the hydration conditions which are indeed shown to be both necessary and sufficient for the formal reduction of the scattering equations to Debye’s form. It may therefore, be possible to use light scattering to investigate the state of hydration of such molecules in a solvent and to investigate the three two-particle correlation functions of such systems.

scholarly journals Polyethyleneimine as tracer particle for (immuno) electron microscopy.

1977 ◽  
Vol 25 (5) ◽  
pp. 384-387 ◽  
Author(s):  
J W Schurer ◽  
J Hoedemaeker ◽  
I Molenaar
Keyword(s):  
Electron Microscopy ◽  
Molecular Weight ◽  
Small Molecules ◽  
Phosphotungstic Acid ◽  
Tracer Particle ◽  
Anionic Sites ◽  
Molecular Weights ◽  
Immuno Electron Microscopy ◽  
Marker Particle ◽  
Electron Microscopical

Polyethyleneimine (PEI) is proposed as a tracer for use in electron microscopical investigations. Relative small molecules are available (molecular weight 600-60,000). PEI is soluble in water; it is not visible in the electron microscope without further treatment, but can easily be detected as a particle by contrastting it with phosphotungstic acid or OsO4. Using PEI of a molecular weight of 40,000, particles of 10 nm diameter can be produced. The strong cationic character of PEI results in electrostatical binding to anionic sites. Hence perfusion and immersion of tissues with PEI of various molecular weights offers possibilities to either study the location of anionic sites or pathways of transport. Anionic sites could be demonstrated in the normal and pathologic glomerular basement membrane. Work on the use of PEI as a marker particle in immunoelectronmicroscopy is in progress.

LC–TOF–MS methods to quantify siRNAs and major metabolite in plasma, urine and tissues

Bioanalysis ◽  
2019 ◽  
Vol 11 (21) ◽  
pp. 1983-1992 ◽  
Author(s):  
Lakshmi Ramanathan ◽  
Helen Shen
Keyword(s):  
High Resolution ◽  
Small Molecules ◽  
Antisense Strand ◽  
Bioanalytical Method Validation ◽  
S1 Nuclease ◽  
Molecular Weights ◽  
Sense Strand ◽  
Tissue Lysate ◽  
Probe Hybridization ◽  
High Resolution Mass Spectrometer

There are a few different bioanalytical approaches that have been used for the quantification of siRNA in biological matrices, such as S1 nuclease protection ‘cutting ELISA’, fluorescent probe hybridization HPLC, HPLC UV, LC–MS/high-resolution accurate-mass (HRAM) and LC–MS/MS. We have developed and validated plasma assays for several oligonucleotides such as GalNAc-conjugated siRNA, using uHPLC and high-resolution mass spectrometer by TOF detection. Although the molecular weights are in the range of 7000–9000, we were able to meet the same assay acceptance criteria as for the small molecules based on regulatory bioanalytical method validation guidance. The antisense strand and the sense strand can both be monitored. The method was also used in the tissue lysate matrices without a full validation.

Ultracentrifugal Determination of Molecular Weights of Small Molecules by the Archibald Procedure1

1954 ◽  
Vol 76 (12) ◽  
pp. 3342-3344 ◽  
Author(s):  
Raymond A. Brown ◽  
David Kritchevsky ◽  
Maurice Davies
Keyword(s):  
Small Molecules ◽  
Molecular Weights

scholarly journals The Isolation of Aggregates of Spectrin From Bovine Erythrocyte Membranes

1975 ◽  
Vol 28 (3) ◽  
pp. 259 ◽  
Author(s):  
GB Ralston
Keyword(s):  
Ionic Strength ◽  
Sodium Dodecyl Sulphate ◽  
Sodium Dodecyl ◽  
Gel Filtration ◽  
Sedimentation Velocity ◽  
Sedimentation Equilibrium ◽  
Erythrocyte Membranes ◽  
Bovine Erythrocyte ◽  
Molecular Weights ◽  
Wide Range

Aggregated states of spectrin from bovine erythrocyte membranes can be detected in sedimentation velocity experiments. These aggregates have been isolated by means of gel filtration on columns of 4 % agarose. They appear to be stable over a wide range of pH and ionic strength, although they are dissociated by sodium dodecyl sulphate. Sedimentation equilibrium measurements yielded values of 960000 and 480000 for the molecular weights of the major aggregates, corresponding to a tetramer and dimer, respectively. The presence of different aggregated states in spectrin preparations may explain the wide variation in the reported physica~ properties of spectrin.

scholarly journals Mechanically Triggered Carbon Monoxide Release with Turn-On Aggregation-Induced Emission

2021 ◽  
Author(s):  
Yunyan Sun ◽  
William Neary ◽  
Zach Burke ◽  
Hai Qian ◽  
Lingyang Zhu ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Small Molecules ◽  
Mechanical Stress ◽  
Small Molecule ◽  
Mechanochemical Reaction ◽  
Aggregation Induced Emission ◽  
Molecular Weights ◽  
Future Design ◽  
Turn On ◽  
Dynamic Therapy

Polymers that release functional small molecules under mechanical stress potentially serve as next-generation materials for catalysis, sensing, and mechanochemical dynamic therapy. To further expand the function of mechanoresponsive materials, the discovery of chemistries capable of small molecule release are highly desirable. In this report, we detail a non-scissile bifunctional mechanophore (i.e., dual mechano-activated properties) based on a unique mechanochemical reaction involving norborn-2-en-7-one (NEO). One property is the release of carbon monoxide (CO) upon pulsed solution ultrasonication. A release efficiency of 58% is observed at high molecular weights (Mn = 158.8 kDa), equating to ~154 molecules of CO re-leased per chain. The second property is the bright cyan emission from the macromolecular product in its aggregated state, resulting in a turn-on fluorescence readout coincident with CO release. This report not only demonstrates a unique strategy for the release of small molecule in a non-scissile way, but also guides future design of force-responsive aggregation-induced emission (AIE) luminogens.

scholarly journals Indacenodipyrene Containing Small Molecules and Ladder Polymers

2021 ◽  
Author(s):  
Ain Uddin ◽  
Kyle Plunkett
Keyword(s):  
Small Molecules ◽  
Field Effect Transistors ◽  
Organic Field Effect Transistors ◽  
Molecular Weights ◽  
Highest Occupied Molecular Orbital ◽  
Precursor Polymers ◽  
Palladium Catalyzed ◽  
Ladder Polymers ◽  
Planar Materials ◽  
Lowest Unoccupied Molecular Orbitals

A series of s-indaceno[1,2,3-cd:5,6,7-c'd']dipyrene-containing small molecule and ladder polymers were prepared using a palladium catalyzed arylation reaction. Precursor polymers and their resulting ladder polymers with molecular weights up to 13 kDa were prepared. The rigid, planar materials possessed highest occupied molecular orbital (HOMO) energies of -5.39 to -5.23 eV, lowest unoccupied molecular orbitals (LUMO) energies of -2.42 eV to -2.98 eV, and optical gaps of 1.68 to 2.03 eV. Organic field effect transistors were prepared with derivatives giving hole mobilities up to 2.5 X 10-5 cm2V-1s-1.

Sign in / Sign up

Export Citation Format

Share Document