3 research outputs found
Nanoscale Understanding of Thermal Aggregation of Whey Protein Pretreated by Transglutaminase
Nanoscale structures of whey protein isolate (WPI) pretreated
by
microbial transglutaminase (mTGase) and subsequent heating were studied
in this work and were correlated to zeta-potential, surface hydrophobicity,
thermal denaturation properties, and macroscopic turbidity and viscosity.
Dispersions of 5% w/v WPI were pretreated by individual or sequential
steps of preheating at 80 °C for 15 min and mTGase, used at 2.0–10.2
U/g WPI for 1–15 h, before adjustment of the pH to 7.0 and
to 0–100 mM NaCl for heating at 80 °C for 15 and 90 min.
The zeta potential and surface hydrophobicity of WPI increased after
all pretreatment steps. Preheating increased cross-linking reactivity
of WPI by mTGase, corresponding to significantly increased denaturation
temperature. Particle size analysis and atomic force microscopy revealed
that structures of sequentially pretreated WPI remained stable after
heating at 100 mM NaCl, corresponding to transparent dispersions.
Conversely, WPI pretreated by one step aggregated at only 100 mM NaCl
and resulted in turbid dispersions. Besides reporting a practical
approach to produce transparent beverages, nanoscale phenomena in
the present study are important for understanding whey protein structures
in relevant applications
A Novel Approach of Periodate Oxidation Coupled with HPLC-FLD for the Quantitative Determination of 3‑Chloro-1,2-propanediol in Water and Vegetable Oil
A novel approach of periodate oxidation
coupled with high-performance
liquid chromatography (HPLC)–fluorescence detection (FLD) for
the quantitative determination of 3-chloro-1,2-propanediol (3-MCPD)
has been established. The essence of this approach lies in the production
of chloroacetaldehyde by the oxidization cleavage of 3-MCPD with sodium
periodate and the HPLC analysis of chloroacetaldehyde monitored by
an FLD detector after fluorescence derivatization with adenine. The
experimental parameters relating to the efficiency of the derivative
reaction such as concentration of adenine, chloroacetaldehyde reaction
temperature, and time were studied. Under the optimized conditions,
the proposed method can provide high sensitivity, good linearity (<i>r</i><sup>2</sup> = 0.999), and repeatability (percent relative
standard deviations between 2.57% and 3.44%), the limits of detection
and quantification were 0.36 and 1.20 ng/mL, respectively, and the
recoveries obtained for water samples were in the range 93.39–97.39%.
This method has been successfully applied to the analysis of real
water samples. Also this method has been successfully used for the
analysis of vegetable oil samples after pretreatment with liquid–liquid
extraction; the recoveries obtained by a spiking experiment with soybean
oil ranged from 96.27% to 102.42%. In comparison with gas chromatography
or gas chromatography–mass spectrometry, the proposed method
can provide the advantages of simple instrumental requirement, easy
operation, low cost, and high efficiency, thus making this approach
another good choice for the sensitive determination of 3-MCPD
Creating “Living” Polymer Surfaces to Pattern Biomolecules and Cells on Common Plastics
Creating
patterns of biomolecules and cells has been applied widely
in many fields associated with the life sciences, including diagnostics.
In these applications it has become increasingly apparent that the
spatiotemporal arrangement of biological molecules in vitro is important
for the investigation of the cellular functions found in vivo. However,
the cell patterning techniques often used are limited to creating
2D functional surfaces on glass and silicon. In addition, in general,
these procedures are not easy to implement in conventional biological
laboratories. Here, we show the formation of a living polyÂ(ethylene
glycol) (PEG) layer that can be patterned with visible light on plastic
surfaces. This new and simple method can be expanded to pattern <i>multiple</i> types of biomolecule on either a previously formed
PEG layer or a plastic substrate. Using common plastic wares (i.e.,
polyethylene films and polystyrene cell culture Petri-dishes), we
demonstrate that these PEG-modified surfaces have a high resistance
to protein adsorption and cell adhesion, while at the same time, being
capable of undergoing further molecular grafting with bioactive motifs.
With a photomask and a fluid delivery system, we illustrate a flexible
way to immobilize biological functions with a high degree of 2D and
3D spatial control. We anticipate that our method can be easily implemented
in a typical life science laboratory (without the need for specialized
lithography equipment) offering the prospect of imparting desirable
properties to plastic products, for example, the creation of functional
microenvironments in biological studies or reducing biological adhesion
to surfaces