Biopolymers, such as silk fibroin, collagen, and chitosan, are promising candidates for a variety of applications that merge the fields of biomedical optics and biomaterials. Biocompatible silk fibroin, in particular, shows promise as a biomaterial, based on a number of attributes.[1] Silk fibroin is the strongest and toughest natural fiber known and is easily formed into robust films of thermodynamically stable beta-sheets of a controllable range of thicknesses (between tens of nanometers and hundreds of micrometers). [1][2][3] These films have excellent (ca. 95%) optical transparency across the visible range and can be easily characterized and biochemically functionalized because of the all-aqueous processing, broadening their overall value. It is possible to form such silk fibroin films, having intricate 2D or 3D nano-or micropatterns, through a softlithography-based simple casting technique. This technique enables the fabrication of (at least) sub-30 nm transverse features in silk fibroin films, when cast at ambient conditions from an aqueous silk solution. The elegance of this method is in its simplicity; the fabrication of such features is completed in the absence of additional harsh chemicals, salts, or high pressures that traditionally accompany most micro-and nanofabrication techniques. By employing this simple casting technique, high-quality films that contain a wide spectrum of nano-and micropatterns can be fabricated. These films are of great consequence for use in a variety of studies based in biomedical optics.In this Communication we report on a process developed for the construction of silk fibroin-based nano-and micropatterned films. This process includes the methods for producing ultrapure silk fibroin solution, the aqueous casting process for patterning silk fibroin films, and the characterization of the smallest transverse nanopatterns realized in silk fibroin films to date.Production of the silk fibroin solution begins with the purification of harvested Bombyx mori cocoons. Sericin, a water-soluble glycoprotein that binds fibroin filaments, is removed from the fibroin strands by boiling the cocoons in a 0.02 M aqueous solution of sodium carbonate for 45 min. [4] Upon completion of this step, the remaining fibroin bundle is rinsed thoroughly in Milli-Q water and allowed to dry overnight. The dry fibroin bundle is then dissolved in a 9.3 M aqueous solution of lithium bromide at 60 8C for 4 h. The lithium bromide salt is then extracted from the solution over the course of three days, through a water-based dialysis process. The resulting solution is extracted from the dialysis cassette (Slide-a-Lyzer, Pierce, molecular weight cut-off (MWCO) 3500) and remaining particulates are removed through centrifugation and syringe-based microfiltration (5 mm pore size, Millipore Inc, Bedford, MA). This process enables the production of 8-10% w/v silk fibroin solution of excellent quality and stability. The purification step is particularly important for the generation of high-quality optical films with maxim...

Contrast-enhanced mammography (CEM) is a developing modality used for the workup and management of breast cancer. Although diagnostic imaging modalities such as mammography and US have historically been the mainstays of initial breast cancer workup, recent advances in breast MRI have allowed better disease evaluation. However, MRI is not always readily available, can be time consuming, and is contraindicated in certain patients. CEM is an alternative to US and MRI, and it can be used to obtain contrast material-enhanced information and standard mammograms simultaneously. A CEM examination is shorter than that of MRI, and the modalities have similar rates of sensitivity to detect lesions. CEM also costs less than MRI. The authors evaluate clinical uses of CEM and discuss the literature supporting these indications. ©

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