<div>3.4.3 Recognition selectivity of MTCFs@SIP@CBMA</div><div>Taking isoelectric point and molecular weight as investigating factors,
OVA, HSA, Lyz, and Bhb were selected as protein analogues to investigate
the recognition selectivity of MTCFs@SIP@CBMA to BSA. The adsorption
capacities of MTCFs@SIP@CBMA and MTCFs@NIP@CBMA on BSA and other four
proteins are illustrated in Figure 8. The IF values are listed above the
histogram. Obviously, MTCFs@SIP@CBMA exhibited a higher adsorption
capacity and IF for BSA than the other four proteins. This was explained
by that BSA matched the imprinting sites of MTCFs@SIP@CBMA in
three-dimensional space and functional group arrangement. HSA not only
possessed an isoelectric point and molecular weight similar to BSA, but
also their three-dimensional conformation and 60% amino acid sequence
were also very similar. Thus, the adsorption capacity and IF of
MTCFs@SIP@CBMA to HSA ranked second. However, the adsorption capacity
and IF of HSA were much lower than those of BSA because the exposed
functional groups were different from BSA and were affected by the
anti-protein adsorption segments.
The isoelectric point of OVA was similar to that of BSA, but the
molecular weight was smaller. The molecular weight of Bhb was close to
that of BSA, while Lyz had a smaller molecular weight. However, due to
the mismatching of charge and the effect of anti-protein adsorption
chain segments, the adsorption capacities and IF values of
MTCFs@SIP@CBMA for Bhb and Lyz were not high. In view of above analysis,
the order of adsorption capacities and IF values of MTCFs@SIP@CBMA for
the other four proteins was HSA &gt; OVA &gt; Bhb
&gt; Lyz. The β values calculated by IF are listed in Table
S1. The β values of MTCFs@SIP@CBMA for OVA, HSA, Lyz and Bhb were 5.81,
5.25, 6.67 and 6.03, indicating that MTCFs@SIP@CBMA could selectively
identify BSA. From above results
the conclusion can be inferred
that the introduction of CBMA anti-protein adsorption chain segments can
indeed improve the recognition selectivity of imprinted materials.</div><div>Figure 8 Selective adsorption of MTCFs@SIP@CBMA and MTCFs@NIP@CBMA
toward BSA, OVA, HSA, Lyz and Bhb. Error bars represent ± standard
deviations, n = 3.</div><div>3.4.4 Competitive adsorption</div><div>In order to further evaluate the recognition selectivity of
MTCFs@SIP@CBMA fibers, adsorption experiments were carried out with
binary mixed protein of Bhb and BSA as adsorption objects. The mixed
proteins (C<sub>Bhb</sub>=C<sub>BSA</sub>=0.1 mg/mL) were
adsorbed with 1 mg MTCFs@SIP@CBMA or MTCFs@NIP@CBMA for 30 min. After
magnet separation, the absorption spectrum of proteins in supernatants
was scanned by UV-vis spectrophotometer with a scanning range of 250-550
nm. As can be seen from Figure 9a, the absorbance of the mixed proteins
at 278 nm decreased significantly after adsorption by MTCFs@SIP@CBMA,
while the absorbance at 409 nm remained almost unchanged. When
MTCFs@NIP@CBMA was selected as the adsorbent, BSA was adsorbed and Bhb
was simultaneously adsorbed (the absorbance at 278 nm and 409 nm were
both reduced). The results showed that MTCFs@SIP@CBMA could selectively
recognize BSA in binary mixed proteins while MTCFs@NIP@CBMA could not.
Moreover, SDS-PAGE gel electrophoresis was used to analyze whether
MTCFs@SIP@CBMA can specifically recognize BSA from the five-component
mixed protein solutions of BSA, OVA, HSA, Lyz, and Bhb. The results are
given in Figure 9b. Compared with lane 2, the intensity of the
corresponding BSA band in channel 3 was weakened, while the intensity of
other protein bands hardly changed. Compared lane 4 with lane 2, it was
found that the band strength of each protein did not change
significantly. In lane 5, only a BSA band was present in the primary
eluent fractions of MTCFs@SIP@CBMA. The above results indicated that
MTCFs@SIP@CBMA could also specifically recognize BSA from multicomponent
mixed proteins. In summary, MTCFs@SIP@CBMA demonstrated outstanding
recognition selectivity for BSA, which was ascribed to the reduction of
non-specific adsorption by anti-protein adsorption chain CBMA grafted on
the surface of the imprinted layer.</div>