Nanoporous carbon capture materials from sustainable sources

Rising CO2 levels in the atmosphere from anthropogenic sources can be seen as one of the greatest problems faced by mankind in modern history. CO2 capture and subsequent storage or utilisation is one possible solution to increasing CO2 levels in the short-term, until humanity is less reliant on fossil fuels. This thesis will investigate currently available state of the art CO2 capture technologies and provide a critical evaluation on their suitability. Furthermore, current research into the storage and utilisation of captured CO2 will also be studied and the long-term suitability of these approaches to increasing CO2 levels determined. New solid-state CO2 adsorption materials have been developed using waste polymeric materials as the primary agent for selective adsorption of CO2. The approach of using waste materials for CO2 adsorption is advantageous in that the waste material is being used to deal with another waste material, namely CO2. The waste materials utilised in this research were chitosan, a waste material derived from chitin, a large waste from the seafood industry, and polyvinylchloride (PVC), a polymer mainly used in the fabrication of household products. It is demonstrated in this thesis that with minimal modification, these waste materials can be utilised for the capture of CO2 at levels comparable to that of the currently available state-of-the-art materials

Sustainable CO2 adsorbents prepared by coating chitosan onto mesoporous silicas for large-scale carbon capture technology

In this article, we report a new sustainable synthesis procedure for manufacturing chitosan/silica CO2 adsorbents. Chitosan is a naturally abundant material and contains amine functionality, which is essential for selective CO2 adsorptions. It is, therefore, ideally suited for manufacturing CO2 adsorbents on a large scale. By coating chitosan onto high-surface-area mesoporous silica supports, including commercial fumed silica (an economical and accessible reagent) and synthetic SBA-15 and MCF silicas, we have prepared a new family of CO2 adsorbents, which have been fully characterised with nitrogen adsorption isotherms, thermogravimetric analysis/differential scanning calorimetry, TEM, FTIR spectroscopy and Raman spectroscopy. These adsorbents have achieved a significant CO2 adsorption capacity of up to 0.98 mmol g−1 at ambient conditions (P=1 atm and T=25 °C). The materials can also be fully regenerated/recycled on demand at temperatures as low as 75 °C with a >85 % retention of the adsorption capacity after 4 cycles, which makes them promising candidates for advanced CO2 capture, storage and utilisation technology

Increasing magnetite contents of polymeric magnetic particles dramatically improves labeling of neural stem cell transplant populations

Safe and efficient delivery of therapeutic cells to sites of injury/disease in the central nervous system is a key goal for the translation of clinical cell transplantation therapies. Recently, 'magnetic cell localization strategies' have emerged as a promising and safe approach for targeted delivery of magnetic particle (MP) labeled stem cells to pathology sites. For neuroregenerative applications, this approach is limited by the lack of available neurocompatible MPs, and low cell labeling achieved in neural stem/precursor populations. We demonstrate that high magnetite content, self-sedimenting polymeric MPs [unfunctionalized poly(lactic acid) coated, without a transfecting component] achieve efficient labeling (≥90\%) of primary neural stem cells (NSCs)-a 'hard-to-label' transplant population of major clinical relevance. Our protocols showed high safety with respect to key stem cell regenerative parameters. Critically, labeled cells were effectively localized in an in vitro flow system by magnetic force highlighting the translational potential of the methods used

Neuropeptide Y (NPY) and peptide YY (PYY) effects in the epididymis of the guinea-pig: evidence of a pre-junctional PYY-selective receptor

1. The effects of peptide YY (PYY), neuropeptide Y (NPY) and structurally related peptides upon field stimulation-induced and phenylephrine-mediated contractile responses in the cauda epididymis of the guinea-pig were investigated. 2. Preparations of cauda epididymis responded to field stimulation with contractions which were completely attenuated by both the neurotoxin, tetrodotoxin (500 nM), and also by the α-adrenoceptor antagonist, phentolamine (3 μM). PYY (n=7) and the truncated peptide analogue PYY(3–36) (n=5) inhibited field stimulation-induced contractions (pIC(50)+s.e.mean: 8.9±0.2 and 9.4±0.2, respectively). Pancreatic polypeptide (PP, up to 1 μM, n=6), NPY (up to 100 nM, n=6) and the NPY analogues [Leu(31),Pro(34)]NPY (n=6) and NPY (13–36) (both up to 1 μM, n=5) had no significant effect. 3. The NPY Y(1) receptor antagonist BIBP3226 ((R)-N2-(diphenylacetyl)-N[(4-hydroxyphenyl)-methyl]-argininamide) at 750 nM (n=6) and 7.5 μM (n=6) did not affect the PYY-mediated inhibition of field stimulation-induced contractions (pIC(50) 8.9±0.3 and 9.0±0.3, respectively). In the presence of BIBP3226 (7.5 μM), NPY (n=6) inhibited field stimulation-induced contractions (pIC(50) 8.0±0.2). 4. NPY, PYY and PYY(3–36) inhibited [(3)H]-noradrenaline release from preparations of epididymis (pIC(50) values 7.9±0.7, 9.6±0.8 and 10.0±0.9, respectively, all n=6). The agonists PP and [Leu(31),Pro(34)]PYY (both up to 100 nM) were without significant effect (both n=6). 5. In preparations of cauda epididymis, stimulated with threshold concentrations of the α(1)-adrenoceptor agonist, phenylephrine (1 μM), both NPY (n=6) and PYY (n=7) elicited concentration-dependent increases in contractile force (with pEC(50) values of 8.9±0.2 and 8.6±0.1, respectively). The effects of both NPY (n=6) and PYY (n=6) were antagonized by preincubation with BIBP3226 (75 nM; apparent pK(B)±s.e. values 8.3±1.0 and 8.2±0.6, respectively). The peptide analogues NPY(13–36) (n=5), PYY (3–36) (n=7) and [Leu(31),Pro(34)]NPY (n=5) did not significantly augment responses to threshold concentrations of phenylephrine. 6. These results are consistent with the proposal that distinct NPY receptors mediate the (prejunctional) inhibition of field stimulation-induced contractions and the (postjunctional) potentiation of responses to phenylephrine in the cauda epididymis of the guinea-pig. The rank order of agonist potency (NPY⩾PYY≫NPY(13–36), [Leu(31),Pro(34)]NPY and PYY(3–36) and the high potency of BIBP3226 indicate that the postjunctional receptor may be Y(1)-like. The rank orders of agonist potency in inhibiting field stimulation-induced contractile responses and [(3)H]-noradrenaline release (PYY(3–36)⩾PYY> NPY≫PP, NPY(13–36), [Leu(31),Pro(34)]NPY and PYY(3–36)⩾PYY>NPY≫;PP,[Leu(31),Pro(34)]PYY, respectively) are consistent with the action of these peptides at a PYY-preferring receptor subtype, which may be distinct from the presently characterized NPY receptor subtypes