Lysine-Grafted MCM-41 Silica as An Antibacterial Biomaterial

Abstract: A facile strategy for zwitterionization of bioceramics based on direct incorporation of L-lysine amino acid via the ε-amino group onto mesoporous MCM-41 materials is proposed. FTIR studies of lysine-grafted MCM-41 (MCM-LYS) showed simultaneously bands at 3080 and 1540 cm−1 and bands at 1625 and 1415 cm−1 corresponding to -NH3+/COO− pairs, demonstrating the incorporation of the amino acid on the material surface keeping its zwitterionic character. Both elemental and thermogravimetric analyses showed that the amount of grafted lysine was 8 wt % based on the bioceramic total weight. Moreover, MCM-LYS material exhibited a reduction of adhesion of S. aureus and E. coli bacteria in 33 and 50%, respectively at physiological pH, as compared with pristine MCM-41. Biofilm studies onto surfaces showed that lysine functionalization elicited a reduction of the area covered by S. aureus biofilm from 42% to only 5% (88%). This research shows a simple and effective approach to chemically modify bioceramics using single amino acids that provide zwitterionic functionality, useful to develop new biomaterials able to resist bacterial adhesion

Controlled-width track in through silicon via using 3D holographic photolithography with modified electrodepositable photoresist

We present a novel lithographic process for patterning controlled-width tracks onto anisotropically micromachined silicon. The technique is based on the use of computer-generated holographic masks with a custom alignment and exposure tool. Experimental and simulation results are presented. 3D holographic photolithography significantly reduces the problem normally present with photolithography on non-planar surfaces—namely diffractive line broadening. A negative-acting electrodepositable photoresist (InterVia 3D-N) is used in the study. Its deposition onto the 3D substrate is optimized by modification of coating temperature and thickness and of pre-exposure bake conditions. We show the successful patterning of a constant-width 8 µm line down the sloping sidewall of a 500 µm thick silicon wafer. This is beyond the conventional resolution limit and indicates the potential of the technique for realizing high-density vertical routing in electronic packages and MEMS

Dual wavelength optical metrology using ptychography

We describe an experimental implementation of ptychography to optical metrology, in particular topography measurement, in combination with the dual wavelength method. This is the first published account of the application of the dual wavelength method to ptychography or any other phase retrieval method in order to obtain surface height information over a wide range of scales, from small fractions of a wavelength up to many tens of wavelengths, in reflection mode. Moreover, the work presented here is the first report on the application of lensless reflection mode ptychography. Advantages of the ptychographic dual wavelength method are compared with other optical topography measurement techniques, especially with respect to the experimental procedures and constraints and the analysis of the data. We show that dual wavelength ptychography can remove material-specific phase changes which adversely affect topography measurements using white light profilometry

Three-dimensional curvy electronics created using conformal additive stamp printing

Electronic devices are typically manufactured in planar layouts, but many emerging applications, from optoelectronics to wearables, require three-dimensional curvy structures. However, the fabrication of such structures has proved challenging due, in particular, to the lack of an effective manufacturing technology. Here, we show that conformal additive stamp (CAS) printing technology can be used to reliably manufacture three-dimensional curvy electronics. CAS printing employs a pneumatically inflated elastomeric balloon as a conformal stamping medium to pick up pre-fabricated electronic devices and print them onto curvy surfaces. To illustrate the capabilities of the approach, we use it to create various devices with curvy shapes: silicon pellets, photodetector arrays, electrically small antennas, hemispherical solar cells and smart contact lenses. We also show that CAS printing can be used to print onto arbitrary three-dimensional surfaces