Investigate Protein Adsorption Research Articles

Human Serum Albumin as a Probe for Protein Adsorption to Nanopartides: Relevance to Biodistribution

A range of poloxamers and poloxamines were adsorbed to biodegradable poly(lactide-coglycolide) (PLGA) and non-biodegradable polystyrene (PS) particulate systems in order to alter their surface characteristics and produce potential drug targeting systems. Human serum albumin (HSA) was chosen as a model protein to investigate protein adsorption to the above systems and was quantified by two techniques. I125 radiolabelled HSA proved to be a useful probe for determining protein adsorption but was limited by a modification that occurred on storage. Also, HSA eluted from the particle surface was quantified by densitometry following it's development on an SDS-PAGE gel. Both techniques produced similar results. For cleaned coated PS particles it was found that the PEO chain length and the molecular structure of the block copolymer were important in preventing protein adsorption. The presence of excess block copolymer in the uncleaned preparations resulted in further suppression of HSA adsorption, which was thought to be due to their detergent properties. Due to the different results obtained with similarly coated PLGA particles, it was concluded that the block copolymers adsorb onto the surface of me PLGA particles in a different conformation to those adsorbed onto PS particles. Correlating in vivo biodistribution in terms of the prevention of protein (opsonin) adsorption was of only limited success and it was concluded that adsorption data for a single model protein can only be used with caution to predict the in vivo behaviour of colloidal targeting systems.

Coatings reduce the fouling of microfiltration membranes

The effect of polymeric phospholipid analogue coatings on the performance of microfiltration membranes in the filtration of protein solutions was assessed by cross-flow filtration. Affinity gold stains and transmission electron microscopy were used to investigate protein adsorption to the membranes. Polyvinylidene difluoride (PVDF) and cellulose acetate (CA) microfiltration membranes were coated with the phospholipid analogue by a grafting reaction. Phospholipid coating improved the flux of both PVDF and cellulose acetate membranes, but was more effective on the former. Electron microscopy confirmed the reduction in fouling of the coated membranes.

A fluorescence technique for investigating protein adsorption phenomena at a colloidal silica surface

A fluorescence method for monitoring protein adsorption phenomena has been developed utilizing an unmodified spectrofluorometer and solvated silica nanoparticles 9 nm in diameter as the solid surface. Since the nanoparticles are approximately the same size as the protein, the scattering (about 2%) at 295 nm has little effect on the general spectral data. This technique allows for the study of surface adsorption in solution on virtually any solid material that can be produced in this small colloidal form. Two well-defined proteins with different structural stabilities, bovine serum albumin (BSA) with low conformational stability and lysozyme with high conformational stability, were chosen as models for the initial investigations. The intrinsic fluorescence of the two proteins was analysed prior to and after the addition of the silica nanoparticles. The results demonstrate that BSA produces the largest fluorescence change with both a large fluorescence intensity decrease and a blue shift of 10 nm. Being more structurally stable, lysozyme shows no shift in wavelength, but the adsorption does seem to diminish some of the vibrational relaxation pathways and the relative fluorescence intensity increases.

Experimental methods for investigating protein adsorption kinetics at surfaces.

The adsorption of proteins at the solid-liquid interface is a process of fundamental importance in nature. Extensive reviews (MacRitchie, 1978; Andrade & Hlady, 1986; Norde, 1986) testify to the strong interest which has been shown in the problem during the past few decades. Norde & Lyklema (1978) have rightly pointed out that protein adsorption is scientifically intriguing; the phenomenology is complicated and includes many presently apparently irreconcilable observations.

Integrated optical input grating couplers as biochemical sensors

The sensors make use of the angular resonance in the grating coupler excitation of guided waves in planar waveguides. Surface relief gratings with 1200 lines/mm on SiO 2TiO 2 waveguides on glass were used at the He Ne laser wavelength λ = 632.8 nm to investigate protein adsorption onto the waveguide surface, and the feasibility of immunochemical sensing. The adsorption of human immunoglobulin G (h-IgG) out of aqueous phosphate buffer solution (PBS) was studied as a function of time and solute concentration, and also the slow partial desorption of the h-IgG from the surface into a pure PBS solution. Refractive indices, thicknesses and surface coverages of the adsorbed layers were determined. The interaction between h-IgG molecules adsorbed on the waveguide and anti-h-IgG molecules in solution was monitored and the specific immuno-binding was observed. The results show the potential of the method for immunosensing.