Enzyme responsive materials (ERMs) are a class of stimuli responsive materials with broad application potential in biological settings. This review highlights current and potential future design strategies for ERMs and provides an overview of the present state of the art in the area. Mischa ZelzerMischa Zelzer completed his first degree in Chemistry at the Technical University Graz (AT) in 2005. He then moved to the UK where he obtained his PhD from the University of Nottingham in 2009. Subsequently, he joined the University of Strathclyde (UK) in 2010 as a postdoctoral researcher. In 2012, Mischa was awarded a Marie Curie Fellowship and moved to the Technical University of Eindhoven (NL). Mischa's research interests are in stimuli responsive materials and interfaces with a particular emphasis on enzyme responsiveness and biological applications. Simon J. ToddSimon J. Todd after obtaining a BSc (Hons) degree in Biomedical Materials Science from the University of Nottingham, including a final year project under Prof. D. Grant on the functionalisation of diamond-like carbon with albumin, took a year out to travel in North America. He completed a PhD in the construction of enzyme responsive surfaces at the University of Manchester supervised by Dr Ulijn and Dr J. Gough. Simon then went on to work for the award-winning start up company Renephra.

With improved understanding of the design rules for self-assembling peptides, new challenges will be faced to incorporate these materials into dynamic systems of higher complexity and functionality. In this highlight article we discuss very recent advances in these areas. Three areas are covered: (i) molecular networks based on peptides and their interactions including (bio-) catalytically driven systems; (ii) supramolecular functionality, both in the context of biological and nanotechnology applications; (iii) approaches to effectively interface peptides with synthetic and biological materials. We also discuss challenges and opportunities for the design of a new generation of peptide nanomaterials for the next decade.

No abstract

Plasma polymers have been formed from acrylic acid using a pulsed power source. An on-pulse duration of 100 micros was used with a range of discharge off-times between 0 (continuous wave) and 20,000 micros. X-ray photoelectron spectroscopy (XPS) has been used in combination with trifluoroethanol (TFE) derivatization to quantify the surface concentration of the carboxylic acid functionality in the deposit. Retention of this functionality from the monomer varied from 2% to 65%. When input power was expressed as the time-averaged energy per monomer molecule, E(mean), the deposit chemistry achieved could be described using a single relationship for all deposition conditions. Deposition rates were monitored using a quartz crystal microbalance, which revealed a range from 20 to 200 microg m(-2) s(-1), and these fell as COOH functional retention increased. The flow rate was found to be the major determinant of the deposition rate, rather than being uniquely defined by E(mean), connected to the rate at which fresh monomer enters the system in the monomer deficient regime. The neutral species were collected in a time-averaged manner. As the energy delivered per molecule in the system (E(mean)) decreased, the amount of intact monomer increased, with the average neutral mass approaching 72 amu as E(mean) tends to zero. No neutral oligomeric species were detected. Langmuir probes have been used to determine the temporal evolution of the density and temperature of the electrons in the plasma and the plasma potential adjacent to the depositing film. It has been found that even 500 micros into the afterglow period that ionic densities are still significant, 5-10% of the on-time density, and that ion accelerating sheath potentials fall from 40 V in the on-time to a few volts in the off-time. We have made the first detailed, time- and energy-resolved mass spectrometry measurements in depositing acrylic acid plasma. These have allowed us to identify and quantify the positive ion species in the acrylic acid plasma during both the on- and the off- periods. The relative intensities of oligomeric species of the type [nM + H]+ as large as n = 3 were observed to increase in the off-time suggesting vapor phase polymerization after power input to the plasma was ceased. The energy distribution functions of these ions demonstrated that they were produced in the plasma in both the on- and the off-times. This remarkable observation contradicts the assumptions usually made when speculating on pulsed plasma that ions have very short lifetimes, although it is anticipated that radicals still have significantly longer lifetimes, estimated from calculation to be in excess of 1 ms. The increase in average positive ion mass during the off-period can be related to the lower mobility of the heavier components, reducing their relative loss to surfaces, and the polymer chain growth in the gas phase due to the ion-neutral collisions. The implications of these observations are discussed in light of polymerization mechanisms proposed from continuous acrylic...