for their feedback on drafts of the chapters. Professor Mohan Edirisinghe and Professor Kevin Taylor are also thanked for their insightful comments on the manuscript.This book was prepared while CJL was funded by the Engineering and Physical Sciences Council (grant number EP/ P022677/ 1), and we gratefully acknowledge their support of her work. We further thank University College London and King's College London for their support for this endeavour in terms of time, infrastructure and resources.GRW would like to express thanks to Professor Chris Branford-White, Professor Limin Zhu and Professor Deng-Guang Yu for introducing him to the joys of electrospinning way back in 2010.Finally, we thank the editorial team at UCL Press for their great efforts in making this book happen, with special thanks to Dr Chris Penfold for being so patient as the deadlines slipped by. Contents List of figures x List of abbreviations xxviiConTenTs viii vi i i 3.7 pH-controlled delivery 3.8 Pulsatile release 3.9 Multilayer materials 3.10 Thermoresponsive systems 3.11 Emulsion and suspension electrospinning 3.12 Tissue-engineering applications 3.13 Using fibres as sacrificial templates 3.14 Conclusions 3.15 References LisT of fiGuRes xiixi i the jet volume and V 2 is the space the jet is not occupying in the conical frustum. 2.4 The concept of entanglement. (a) Small molecules and low-molecular-weight polymers cannot effectively overlap and entangle. Instead, they flow easily past one another. This leads to low-viscosity solutions which suffer from Rayleigh instability. (b) High-molecular-weight polymers undergo effective entanglement, meaning the force of elongation outweighs the surface tension and permitting electrospinning to be performed. 2.5 A digital photograph depicting bending instabilities during an electrospinning experiment. (Modified with permission from Yu, D. G.; Yu, J. H.; Chen, L.; Williams, G. R.; Wang, X. 'Modified coaxial electrospinning for the preparation of high-quality ketoprofen-loaded cellulose acetate nanofibers.' Carbohydr. Polym. 90 (2012): 1016-1023, with permission from Elsevier. Copyright Elsevier 2012.) 2.6 Defects that may arise during fibre solidification, showing (a) smooth, cylindrical fibres resulting from a welloptimised process; (b) flattened fibres; (c) wrinkled fibres; and (d) merged fibres. (Images (a) and (b) are modified with permission from Yu, D. G.; Yu, J. H.; Chen, L.; Williams, G. R.; Wang, X. 'Modified coaxial electrospinning for the preparation of high-quality ketoprofen-loaded cellulose acetate nanofibers.' Carbohydr. Polym. 90 (2012): 1016-1023, with permission from Elsevier. Copyright Elsevier 2012. Images (c) and (d) are modified with permission from Jia, D.; Gao, Y.; Williams, G. R. 'Core/ shell poly(ethylene oxide)/ Eudragit fibers for sitespecific release.' Int. J. Pharm. 523 (2017): 376-385, with permission from Elsevier.Copyright Elsevier 2017.) 2.7 The effect of solution viscosity on the products from electrohydrodynamic processing. 2.8 Spinneret designs for different types of...

A one-pot single-step novel process has been developed to form microbubbles up to 250 μm in diameter using a pressurized rotating device. The microbubble diameter is shown to be a function of rotational speed and working pressure of the processing system, and a modified Rayleigh-Plesset equation has been derived to explain the bubble-forming mechanism. A parametric plot is constructed to identify a rotating speed and working pressure regime, which allows for continuous bubbling. Bare protein (lysozyme) microbubbles generated in this way exhibit a morphological change, resulting in microcapsules over a period of time. Microbubbles prepared with gold nanoparticles at the bubble surface showed greater stability over a time period and retained the same morphology. The functionalization of microbubbles with gold nanoparticles also rendered optical tunability and has promising applications in imaging, biosensing, and diagnostics.

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scaffolds are made with spinning techniques either using polymer solutions or melts. [ 3,4 ] The primary focus of the spinning technique is the production of fi bers in a scale range from nano-to microrange that resembles the native extracellular matrix (ECM). [5][6][7] Although there has been much research on solution spinning to form fi brous polymer scaffolds for tissue engineering and wound healing applications, little has been reported on melt spinning to fabricate nonwoven scaffolds. [ 8,9 ] Melt spinning does not require solvents that are mostly cytotoxic, therefore it offers a distinct advantage. In addition, the surface topography of the fi brous scaffolds which can affect cellular infi ltration can be better controlled by melt spinning. [ 8,10 ] Poly(ε-caprolactone) (PCL) is one of the most promising linear aliphatic polyesters used extensively in the biomedical field since it is biodegradable in an aqueous medium and biocompatible in biological applications. This semi-crystalline polymer has a low melting point (60 °C) and a glass transition temperature (−60 °C) and therefore it could be fabricated easily into any shape and size. [11][12][13] The superior rheo logical properties and mechanical properties of PCL have A pressurized melt gyration process has been used for the fi rst time to generate poly(ε-caprolactone) (PCL) fi bers. Gyration speed, working pressure, and melt temperature are varied and these parameters infl uence the fi ber diameter and the temperature enabled changing the surface morphology of the fi bers. Two types of nonwoven PCL fi ber constructs are prepared. First, Ag-doped PCL is studied for antibacterial activity using Gram-negative Escherichia coli and Pseudo monas aeruginosa microorganisms. The melt temperature used to make these constructs signifi cantly infl uences antibacterial activity. Neat PCL nonwoven scaffolds are also prepared and their potential for application in muscular tissue engineering is studied with myoblast cells. Results show signifi cant cell attachment, growth, and proliferation of cells on the scaffolds.

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Mucoadhesive delivery systems have attracted remarkable interest recently, especially for their potential to prolong dosage form resident times at sites of application such as the vagina or nasal cavity, thereby improving convenience and compliance as a result of less frequent dosage. Mucoadhesive capabilities need to be routinely quantified during the development of these systems. This is however logistically challenging due to difficulties in obtaining and preparing viable mucosa tissues for experiments. Utilizing artificial membranes as a suitable alternative for quicker and easier analyses of mucoadhesion of these systems is currently being explored. In this study, the mucoadhesive interactions between progesterone-loaded fibers (with varying carboxymethyl cellulose (CMC) content) and either artificial (cellulose acetate) or mucosa membranes are investigated by texture analysis and results across models are compared. Mucoadhesion to artificial membrane was about 10 times that of mucosa, though statistically significant ( p = 0.027) association between the 2 data sets was observed. Furthermore, a hypothesis relating fiber-mucosa interfacial roughness (and unfilled void spaces on mucosa) to mucoadhesion, deduced from some classical mucoadhesion theories, was tested to determine its validity. Points of interaction between the fiber and mucosa membrane were examined using atomic force microscopy (AFM) to determine the depths of interpenetration and unfilled voids/roughness, features crucial to mucoadhesion according to the diffusion and mechanical theories of mucoadhesion. A Kendall's tau and Goodman-Kruskal's gamma tests established a monotonic relationship between detaching forces and roughness, significant with p-values of 0.014 and 0.027, respectively. A similar relationship between CMC concentration and interfacial roughness was also confirmed. We conclude that AFM analysis of surface geometry following mucoadhesion can be explored for quantifying mucoadhesion as data from interfacial images correlates significantly with corresponding detaching forces, a well-established function of mucoadhesion.