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940 results on '"Whittaker, Andrew K."'

216. Amphibian-inspired conductive ionogel stabilizing in air/water as a wearable amphibious flexible sensor for drowning alarms

Author

Feng, Yubin, Zhu, Weihang, Yang, Xinting, Yang, Zhe, Wei, Chenke, Guo, Yukai, Whittaker, Andrew K., Shen, Chun, Zhao, Yue, Qu, Wenrui, Yang, Bai, and Lin, Quan

Abstract

Gel-based sensors have provided unprecedented opportunities for bioelectric monitoring. Until now, sensors for underwater applicants have remained a notable challenge, as most sensors work effectively in air but swell underwater leading to functional failure. Herein, we introduce an innovative amphibian-inspired high-performance ionogel, where multiple supramolecular interactions in the ionogel's network confer good stretchability, elasticity, conductivity, and the hydrophobic C-F bonds play a key role in diminishing water molecule hydration and provide outstanding environmental stability. These unique properties of ionogels make them suitable as wearable amphibious flexible sensors, and the sensors are capable of highly sensitive and stable human motion monitoring in air and underwater. Integration of the designed sensor into an artificial intelligence drowning alarm system, which recognizes the swimmer's movement status by monitoring the amplitude and frequency, especially in the drowning status for real-time alarms. This work provides novel strategies for motion recognition and hazard monitoring in amphibious environments, meeting the new generation of wearable sensors.

Published
2024
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217. Revealing the Chemical Interactions between PMMA and TMA for Insights into Sequential Infiltration Synthesis

Author

McCallum, Francis, Hossain, Md. Daloar, Blakey, Idriss, Peng, Hui, and Whittaker, Andrew K.

Abstract

Sequential infiltration synthesis (SIS) is emerging as an important method for generating novel hybrid inorganic–polymer materials and is predicted to have numerous applications in technologies such as robust thin film materials for lithography, and preparation of materials with specific optical properties. Characterization of the mechanisms of SIS remains a challenge due to the nature of the materials formed in SIS and the dynamic nature of the processes occurring. To assist our understanding, we describe here a solution-based model for assessing the interactions occurring in the SIS chamber. The widely utilized pairing of poly(methyl methacrylate) (PMMA) and trimethyl aluminum (TMA) was chosen for this fundamental study. PMMA and TMA are both soluble in toluene, and importantly this is an inert solvent for TMA. Liquid cell FTIR reveals the formation of complexes of TMA and the ester of PMMA, with a linear relationship between the proportion of complexes formed and the mole ratio of TMA and available ester moieties. Furthermore, liquid cell FTIR, 1H NMR, and 13C NMR spectra show that dimeric TMA is observed when TMA is in excess. Although evidence of significant electron delocalization suggests an increase in the ester activation, it did not lead to reaction products even when TMA was in excess. In order to develop a better understanding of the participation of H2O in the SIS reactions, we developed several strategies for introducing water at various concentrations into the polymer matrix. The resultant nanocomposite materials were characterized by FTIR, DSC, and TGA, further highlighting the chemical changes observed in solution and demonstrating equivalence with interactions occurring in solid polymeric matrices in the conventional SIS process.

Published
2024
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218. Targeted multimodal hyperbranched polymers for imaging and therapy of prostate cancer

Author

Tse, Brian W-C., Pearce, Amanda, Fuchs, Adrian V., Simpson, Joshua D., Yeh, Mei-Chun, Huang, Steve S., Heston, Warren D.W, Williams, Elizabeth D., Whittaker, Andrew K., Thurecht, Kristofer J., Russell, Pamela, Tse, Brian W-C., Pearce, Amanda, Fuchs, Adrian V., Simpson, Joshua D., Yeh, Mei-Chun, Huang, Steve S., Heston, Warren D.W, Williams, Elizabeth D., Whittaker, Andrew K., Thurecht, Kristofer J., and Russell, Pamela

Abstract

Hyperbranched polymers (HBPs) are an emerging class of promising biocompatible agents for cancer imaging and therapy. Their structure allows for conjugation with several specific functionalities. We aimed to assess imaging and therapeutic potential of HBP targeted to prostate cancer (PCa) and loaded with a chemotherapeutic agent.

Published
2016

235. Effect of changes in the surface chemistry and topography of poly(2-hydroxyethyl methacrylate) on the in vitro attachment of human corneal epithelial cells.

Author

Santander-Borrego, Miriem, Chirila, Traian V., Shadforth, Audra M. A., Whittaker, Andrew K., and Blakey, Idriss

Subjects
CELL adhesion, EPITHELIAL cells, CELL lines, AMINO acid sequence, T cells, BIOMATERIALS
Abstract

The effects on cell adhesion induced by changes in the topography and chemistry of poly(2-hydroxyethyl methacrylate) hydrogel surfaces were investigated in vitro using the human corneal epithelial cell line, HCE-T. Poly(2-hydroxyethyl methacrylate) surfaces with a lotus-leaf-like topography and poly(2-hydroxyethyl methacrylate) surfaces with a flat topography, but functionalized with the cell-adhesive peptide sequence Arg–Gly–Asp, both enhanced attachment of HCE-T cells as compared to flat, non-functionalized poly(2-hydroxyethyl methacrylate) surfaces. However, the simultaneous existence on the same poly(2-hydroxyethyl methacrylate) surface of Arg–Gly–Asp motifs and of lotus-leaf-like topographical patterns led to an apparently antagonistic effect reflected in reduced cell attachment. The study provided additional evidence of the complexity of the cell–biomaterial interactions. [ABSTRACT FROM AUTHOR]

Published
2018
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242. EphA2 as a Diagnostic Imaging Target in Glioblastoma: A Positron Emission Tomography/Magnetic Resonance Imaging Study

Author

Puttick, Simon, primary, Stringer, Brett W., additional, Day, Bryan W., additional, Bruce, Zara C., additional, Ensbey, Kathleen S., additional, Mardon, Karine, additional, Cowin, Gary J., additional, Thurecht, Kristofer J., additional, Whittaker, Andrew K., additional, Fay, Michael, additional, Boyd, Andrew W., additional, and Rose, Stephen, additional

Published
2015
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248. Biocidal Polymers: A Mechanistic Overview.

Author

Chen, Ao, Peng, Hui, Blakey, Idriss, and Whittaker, Andrew K.

Subjects
ANTIMICROBIAL polymers, BIOFILMS, BIOCHEMICAL mechanism of action, ANTIBIOTICS, LITERATURE reviews
Abstract

Bacterial fouling on surfaces is considered a major problem in modern society. Conventional methods to prevent biofilm formation often have little effect and may induce further contamination. In response to this challenge, biocidal polymers have been designed and applied as an alternative approach to kill or inhibit bacteria and prevent the formation of biofilm. These polymers can be grouped into three broad classes, namely antibiotic-releasing polymers, polymeric antibiotics, and antibiotic polymers. Antibiotic polymers are effective against bacteria both in solution and as coatings, through different mechanisms of action. In order to enhance their efficacy, biocidal polymers have been designed with single or combined biocidal and antibiofouling actions. The current review summarizes the mechanisms of action of biocidal polymers, especially antibiotic polymers, both in solution and as coatings. The review also discusses biocidal polymers with multiple functionalities. [ABSTRACT FROM PUBLISHER]

Published
2017
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249. Reactivity Ratios and Sequence Distribution Characterization by Quantitative 13C NMR for RAFT Synthesis of Styrene-Acrylonitrile Copolymers.

Author

Alam, Md. Mahbub, Peng, Hui, Jack, Kevin S., Hill, David J. T., and Whittaker, Andrew K.

Subjects
STYRENE, COPOLYMERS, MONOMERS, NITRILES, ADIPONITRILE, ACRYLONITRILE
Abstract

ABSTRACT The kinetics and reactivity ratios of styrene-acrylonitrile (SA) copolymerization have been studied extensively in bulk and in a variety of solution media using conventional free radical polymerizations (FRPs). Due to the significant difference in the two reactivity ratios for this monomer pair, at certain feed ratios the copolymers display composition drift with conversion due to monomer depletion. In this study, the kinetics of SA copolymerization using Reversible Addition-Fragmentation Chain Transfer (RAFT) has been studied in bulk at 80 °C. The reactivity ratios for the terminal model were calculated from the comonomer sequence distributions for the RAFT process at low conversion for nine different compositions and found to be in the same range as those reported for conventional FRP of SA. The changes in the composition and sequence distribution with conversion were studied for three feed compositions. The copolymers show compositional drift with conversion, except at the azeotropic composition, and match the predictions from the reactivity ratios obtained at low conversion. From quantitative 13C NMR the triad distributions of these copolymers were estimated and found to match the predicted triad distributions as conversion increased. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 919-927 [ABSTRACT FROM AUTHOR]

Published
2017
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