Thin films of protein (BSA, lysozyme) - Polyelectrolyte (PSS) complexes show larger red-shift in optical emissions irrespective of protein conformation

Preparation, characterization and electrical behaviors of PEDOT:PSS-Au/Ag nanocomposite thin films: an ecofriendly approach

“…From the figures, it is clear that the two peaks are present at ≈ 205 and 278 nm, respectively, and both the peaks are assigned due to the presence of aromatic ring in PSS [40,41]. The peak present at ≈ 205 nm is due to the bonding to antibonding, i.e., π-π*, transition, whereas the peak at ≈ 278 nm is due to the bonding to nonbonding, i.e., π-n, transition of the aromatic rings [42][43][44]. From the figure, it is clear that the absorptions of the PSS peaks are higher at the lowest concentration of the nanoparticles; however, the absorption decreases with the increasing nanoparticle concentration.…”

Förster Resonance Energy Transfer-Mediated Globular Protein Sensing Using Polyelectrolyte Complex Nanoparticles

“…However, PEC-0.67 NPs exhibit a prominent emission peak at ≈296 nm and a weak peak at ≈278 nm, while PEC-0.75 NPs exhibit a sharp emission peak at ≈278 nm. The constituent pure PSS exhibits a prominent emission peak at ≈310 nm and a relatively weak peak at ≈360 nm for the same excitation . Therefore, although there are 16, 14, and 12 nm blue shifts for PEC-0.4 NPs, PEC-0.67 NPs, and PEC-1.5 NPs, respectively, the maximum blue shift is found for PEC-0.75 NPs, i.e., ≈32 nm peak shift from the emission peak (more prominent one found at 310 nm) of pure PSS.…”

“…UV–vis absorption spectra of PEC-0.75 NPs are characterized in the presence of all four globular proteins within the concentration range of 5–70 nM. It is found that the peak intensity of PEC-0.75 NPs enhances with an increase in the protein concentration and is also shifted toward the protein absorption peak, which is shown for HSA and Lys in Figure a,b, respectively. The peak obtained at ≈225 nm becomes saturated as the protein concentration increases, whereas the absorption peak at ≈260 nm exhibits a red shift to ≈271 and 275 nm for HSA and Lys, respectively.…”

“…There are two UV–vis absorption peaks found at ≈225 and 260 nm for all PEC NPs, which are originated from the aromatic ring of PSS due to the π → π* and π → n transitions, respectively. 25,33 The PEC-0.4 NPs and PEC-1.5 NPs exhibit photoluminescence emission peaks at ≈294 and 298 nm, respectively, for 225 nm excitation, which is shown in the inset of Figure 4a. However, PEC-0.67 NPs exhibit a prominent emission peak at ≈296 nm and a weak peak at ≈278 nm, while PEC-0.75 NPs exhibit a sharp emission peak at ≈278 nm.…”

“…PSS is optically active due to the π → π* and π → n transitions, which originate from the aromatic ring present inside PSS. Its optical property can be modified by employing different treatments like changing ionic environments, forming composites with different materials, etc. , PSS can be used as an ion exchange resin for medical applications, water softening, removing heavy toxic ions from water, etc. , PDADMAC can be used to modify solid surfaces or to form composites, which are novel materials for removing some organic pollutants such as hydrophobic dyes, isoproturon, etc. , Although different studies are going on for preparing new PEC NPs and for their potential applications, it will be very much effective to provide a simple, efficient, and cost-effective protein sensing material by using PEC NPs.…”