Amphiphilic and amphoteric aqueous soy protein colloids and their cohesion and adhesion to cellulose

Abstract

Highly stable aq. soy protein (SP) colloids have been facilely prepared by high-speed blending (30k rpm, 15 min) to homogeneously disperse up to 97.7 % of soy protein isolate at up to 9 %. Aq. SP colloids were amphoteric with a 4.5 isoelectric point and ζ-potentials ranging from +32.4 mV at pH 2.2 to-39.1 mV at pH 7.1 with respective average hydrodynamic diameters of 157 and 233 nm. Diluted aq. SP colloids (0.0001 %) dried on hydrophilic mica appeared as 6.0 nm thick and 16.4 nm wide disk-like nanoparticulates. Aq. SP colloids were also amphiphilic, reducing water surface tension to 41.2 mN/m at > 0.98 % and could be solvent-exchanged to dimethyl formaldehyde or 4:1 v/v methanol/water. Colloidal SPs exhibited preferential affinity and adhesion to cellulose filter paper to significantly improve the respective tensile modulus and strength by 70 and 42 % at merely 2.8 % dried add-on. The improved cohesion of 6.2 % SPs was evident by drying at 110°C to further increase the respective tensile modulus and strength of cellulose by another 78 and 41 %.

Amphiphilic Protein Microfibrils from Ice-Templated Self-Assembly and Disassembly of Pickering Emulsions

“…This conductivity-derived CAC of 0.19% is equivalent to 0.006 mM, using 280 kDa 3 as the average molecular weight of SPI, which is one-fifth of that (0.98% or 0.035 mM) by surface tension. 5 Such a difference may be attributed to heterogeneous amino acid compositions, highly polydisperse molecular weights (e.g. 8−600 kDa), and varying surface functional groups of SPs.…”

“…colloids at up to 9% by high-speed blending (30k rpm, 15 min). 5 Aq. SP colloids are amphiphilic, capable of reducing water surface tension up to 41.2 mN/m at above 0.98% and being solvent-exchanged to less polar 4:1 v/v methanol/water or dimethylformamde (DMF) at 1 w/v %.…”

Tunable surface wettability and pH-responsive 2D structures from amphiphilic and amphoteric protein microfibrils

“…They were also stabilized on glass slides and scanned with the atomic force microscopy (AFM, MFP-3D, Oxford Instruments Asylum Research, Inc., Santa Barbara, CA) as reported in our prior work. 8 The root mean square (RMS) roughness was calculated based on scanning over a 5 mm  5 mm area (N ¼ 5) with 512  512 pixel resolution. Water contact angle (N ¼ 5) of both surfaces of lms was measured on different batches of samples using the drop shape analysis method to report the average and standard deviation.…”

“…We had previously validated a simple shear force process to disperse the complex and heterogeneous SPs into homogeneous aqueous colloids that exhibit the same amphiphilicity and amphoterism expected of the original SPs. With a 4.51 isoelectric point, 8 aq. SP colloids have been electrospun into ultra-ne (231 nm wide) bers to exhibit excellent amphoteric characteristics to rapidly and selectively adsorb/ desorb both cationic and anionic dyes.…”

Macromolecular design of folic acid functionalized amylopectin–albumin core–shell nanogels for improved physiological stability and colon cancer cell targeted delivery of curcumin

“…The major advantages of protein-based nanogels are their biodegradability, biocompatibility, and non-antigenicity along with flexibility for surface modifications and/or chemical functionalization [8,10]. Additionally, proteins are polyampholytic in nature and enhanced surface hydrophobicity of thermally-treated globular proteins due to unfolding offers these protein-based nanogels to serve as excellent carriers for hydrophobic and charged therapeutic molecules [9,[11][12][13][14]. However, most protein-based nanogels suffer from high susceptibility to proteolytic enzymes during physiological transit [10,15,16] which may consequently result in structural degradation.…”