Polypyrrole (PPy) nanomaterials have been synthesized with varying concentrations (10–40 mM) of anionic surfactant camphor sulphonic acid (CSA) using the chemical polymerization method, and then ...utilized for electromagnetic interference (EMI) shielding applications in the X-band of the microwave frequency range (8.2–12.4 GHz). An observable systematic change in the morphology of the prepared PPy has been noted, with highly aggregated globules transforming into fibular-like structures with an average diameter of approximately 80–120 nm as the CSA concentration increased. Raman and Fourier-transform infrared (FTIR) measurements indicate an increase in the relative intensities of the bipolaronic to polaronic bands, suggesting an improved conjugation of PPy with increasing CSA concentration. The electrical conductivity at room temperature has also been found to increase significantly, from 2.55 S/cm to 35.80 S/cm, as the concentration of CSA surfactant increased from 10 mM to 40 mM. Additionally, the shielding effectiveness (SE) for reflection (SE
R
), SE for absorption (SE
A
), and total SE (SE
T
) have been found to increase with increasing CSA concentration in PPy. The SE
T
values have been found exceeding 35 dB throughout the X-band of the microwave region in PPy nanomaterials with CSA concentrations ≥ 20 mM. It has been observed that CSA-directed polypyrrole exhibits high electrical conductivity, where the SE for absorption (SE
A
) dominates over the SE for reflection (SE
R
). This study suggests that the properties of PPy can be easily tailored for its potential utilization in the fabrication of various EMI shielding devices with improved performance.
In the present study, polyaniline (PAni) thin films have been deposited on glass substrates by in-situ chemical polymerization method using simple dip-coating technique and their opto-electrical ...properties have been studied. The structure of deposited films have been analysed with Fourier transform infrared (FTIR) and Raman spectroscopic techniques to investigate the effect of deposition times on the conjugation length, polaron/bipolaron concentrations and other molecular structure conformations. FTIR and Raman spectroscopy studies reveal increase in both the conjugation length and the polaron/bipolaron carrier concentration with increasing deposition time of the prepared PAni films. The optical properties and optical band-gap of the deposited films have been estimated through UV–visible spectroscopy. The optical band-gap of the deposited films has been found to decrease from 3.31 eV to 3.13 eV with increase in deposition time from 1.5 h to 2.5 h, and further it has been increased slightly to 3.19 eV for the PAni film deposited for 3 h. The electrical conductivity of the deposited films has been found to increase with decrease in optical band gap. The parameters estimated from FTIR, Raman, UV–visible spectroscopy and electrical measurements are in good agreement with each other. It has been observed that the optical and electrical properties of the deposited films depend on the conjugation length of PAni. The polymerization time of 2.5 h has been found to be optimum for obtaining PAni thin films with good electrical conductivity and low optical band gap.
•Polyaniline (PAni) thin films have been grown on glass substrates using in-situ polymerization method for different dipping times.•The effect of polymerization time on optical, electrical and structural properties of the PAni films has been investigated.•Observed optical and electrical properties have been well correlated to the induced structural changes of the PAni films.•Such opto-electrical behaviour suggest the possible utilization of prepared PAni films for various opto-electronic devices.
Polyaniline (PAni) thin film has been synthesized using chemical oxidation route to be used as highly sensitive and selective ammonia (NH
3
) sensors. In situ dip-coating chemical polymerization ...method has been used to grow PAni thin films on glass substrates. The morphological and structural properties of deposited thin film have been examined by scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy and Fourier-transform infrared (FTIR) spectroscopy techniques. Raman and FTIR analysis confirm the successful growth of PAni with long-chain conjugation, whereas SEM micrograph reveals the growth of nanofibrous structured polyaniline. An amorphous structure of the prepared polyaniline with perpendicular periodicity of the conjugated polymer chains has been observed through XRD analysis. The ammonia gas sensing properties, in terms of change in electrical resistance, of the prepared thin film sensor have been investigated at room temperature for different concentrations (25–150 ppm) of ammonia. The deposited film has sensitivity as high as 245% and selectivity (%) of ~ 67% towards ammonia gas (at 150 ppm). The gas sensing response of the deposited film is found to be increased with increasing concentration of ammonia and the observed behaviour is well corroborated with modified Freundlich’s sensitivity versus chemical concentration relation. The effect of humidity on the sensing response and other parameters associated with the figure of merits of sensor like response time, recovery time, selectivity, stability etc. have also been studied. The compensation of charge carriers, i.e. polarons and bipolarons, under the electron donating ammonia gas is considered to be the mechanism of gas sensing for the deposited PAni film. The synthesized PAni thin film sensor with low cost, high sensitivity, selectivity and durability can be utilized for the development of industrial ammonia sensor.
Traditionally the biotransformation of antibody drug conjugates (ADCs) has been evaluated by affinity capture on streptavidin magnetic beads coated with a biotinylated capture reagent. To reduce the ...complexity of the analyte, the affinity captured ADCs are digested with enzymes (“on-bead” or after elution), and/or interchain disulfides are reduced to generate LC and HC fragments prior to mass spectrometry analysis. The “on-bead” enzymatic digestion with IdeS and PNGase F is not efficient and requires longer incubation times to achieve complete Fc and N-glycan removal. This results in a prolonged sample preparation time (7–18 h) and is not suitable for labile ADCs due to the possibility of assay-induced artifacts. To address these challenges, we developed an affinity capture method, where the ADCs are first captured onto streptavidin cartridges coated with a biotinylated generic capture reagent, followed by a 15 min “on-cartridge” digestion with IdeS or PNGase F. The ADCs are then eluted and directly analyzed by LC-HRMS. This method was successfully applied for the biotransformation assessment of site-specific ADCs with payload conjugated on the Fab or Fc. The reduced complexity of the analyte (Fc and N-glycan removal) combined with HRMS enabled sensitive and accurate identification of minor mass change catabolites and changes in the DAR distribution. This automated cartridge-based affinity capture method is fast with a total sample preparation time of less than 4 h (hands-on time of less than 1 h) and can be utilized for any human mAb/ADC independent of isotype (IgG1, IgG2, and IgG4).
The molecular interactions of mouse CD96 to CD155 ligand and to two surrogate antibodies have been investigated. Biophysical and structural studies demonstrate that CD96 forms a homodimer but ...assembles as 1:1 heterodimeric complexes with CD155 or with one of the surrogate antibodies, which compete for the same binding interface. In comparison, the other surrogate antibody binds across the mouse CD96 dimer and recognizes a quaternary epitope spanning both protomers to block exposure of the ligand-binding site. This study reveals different blocking mechanisms and modalities of these two antibodies and may provide insight into the functional effects of antibodies against CD96.
N-linked glycosylation is one of the most common and complex posttranslational modifications that govern the biological functions and physicochemical properties of therapeutic antibodies. We ...evaluated thermal and metabolic stabilities of antibody–drug conjugates (ADCs) with payloads attached to the C’E loop in the immunoglobulin G (IgG) Fc CH2 domain, comparing the glycosylated and aglycosylated Fc ADC variants. Our study revealed that introduction of small-molecule drugs into an aglycosylated antibody can compensate for thermal destabilization originating from structural distortions caused by elimination of N-linked glycans. Depending on the conjugation site, glycans had both positive and negative effects on plasma stability of ADCs. The findings highlight the importance of consideration for selection of conjugation site to achieve desirable physicochemical properties and plasma stability.
The clinical successes of immune checkpoint blockade have invigorated efforts to activate T cell-mediated responses against cancer. Targeting members of the PVR family, consisting of inhibitory ...receptors TIGIT, CD96, and CD112R, has been an active area of clinical investigation. In this study, the binding interactions and molecular assemblies of the PVR family receptors and ligands have been assessed in vitro. Furthermore, the anti-TIGIT monoclonal antibody BMS-986207 crystal structure in complex with TIGIT was determined and shows that the antibody binds an epitope that is commonly targeted by the CD155 ligand as well as other clinical anti-TIGIT antibodies. In contrast to previously proposed models, where TIGIT outcompetes costimulatory receptor CD226 for binding to CD155 due to much higher affinity (nanomolar range), our data rather suggest that PVR family members all engage in interactions with relatively weak affinity (micromolar range), including TIGIT and CD155 interactions. Thus, TIGIT and other PVR inhibitory receptors likely elicit immune suppression via increased surface expression rather than inherent differences in affinity. This work provides an improved foundational understanding of the PVR family network and mechanistic insight into therapeutic antibody intervention.
The molecular interactions of mouse CD96 to CD155 ligand and to two surrogate antibodies have been investigated. Biophysical and structural studies demonstrate that CD96 forms a homodimer but ...assembles as 1:1 heterodimeric complexes with CD155 or with one of the surrogate antibodies, which compete for the same binding interface. In comparison, the other surrogate antibody binds across the mouse CD96 dimer and recognizes a quaternary epitope spanning both protomers to block exposure of the ligand-binding site. This study reveals different blocking mechanisms and modalities of these two antibodies and may provide insight into the functional effects of antibodies against CD96.
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