Electroactive biofilms (EABFs) generated by electrochemically active microorganisms have many potential applications in bioenergy and chemicals production. Biofilm electroactivity can have a significant impact on the yield and efficiency of the conversion processes. This review assesses the effects of process and design parameters on the growth and activity of biofilms in bioelectrochemical systems (BESs). First we compare the role of planktonic and biofilm-forming microorganisms in BESs. The effect of physical, chemical, and electrochemical operating parameters such as flow rate, temperature, pH, ionic strength, substrate concentration and loading, external resistance, and redox potential on EABF attributes such as growth rate, exoelectrogen population, formation of extracellular polymeric substances, mediator synthesis, and rate of electron transfer are discussed. The relationship between electrochemical performance and operating parameters is also examined to identify gaps in assessment and the potential role of future modeling efforts. Similarly, we review what is currently known about the mechanisms that enable electroactive biofilms to transfer electrons and also the contribution of the electrical conductivity of the biofilms' exopolymeric components to BES performance. The current status of cathodic biofilms is also reviewed. Complementary approaches that use process control to optimize EABF composition and biomass density, while minimizing mass transfer effects and changes to system design parameters, are likely necessary to improve BES performance to a level needed for commercial consideration. Finally, future research needs that enable better understanding and optimization of the performance of EABFs are outlined.

Proteomic analysis of formalin-fixed paraffin-embedded (FFPE) tissue would enable retrospective biomarker investigations of this vast archive of pathologically characterized clinical samples that exist worldwide. These FFPE tissues are, however, refractory to proteomic investigations utilizing many state of the art methodologies largely due to the high level of covalently cross-linked proteins arising from formalin fixation. A novel tissue microdissection technique has been developed and combined with a method to extract soluble peptides directly from FFPE tissue for mass spectral analysis of prostate cancer (PCa) and benign prostate hyperplasia (BPH). Hundreds of proteins from PCa and BPH tissue were identified, including several known PCa markers such as prostate-specific antigen, prostatic acid phosphatase, and macrophage inhibitory cytokine-1. Quantitative proteomic profiling utilizing stable isotope labeling confirmed similar expression levels of prostate-specific antigen and prostatic acid phosphatase in BPH and PCa cells, whereas the expression of macrophage inhibitory cytokine-1 was found to be greater in PCa as compared with BPH cells.

We have developed a laser-based printing technique, called biological laser printing (BioLP). BioLP is a non-contact, orifice-free technique that rapidly deposits fL to nL scale volumes of biological material with spatial accuracy better than 5 microm. The printer's orifice-free nature allows for transfer of a wide range of biological material onto a variety of substrates. Control of transfer is performed via a computer-aided design/computer-aided manufacturing (CAD/CAM) system which allows for deposition rates up to 100 pixels of biological material per second using the current laser systems. In this article, we present a description of the apparatus, a model of the transfer process, and a comparison to other biological printing techniques. Further, examples of current system capabilities, such as adjacent deposition of multiple cell types, large-scale cell arrays, and preliminary experiments on creating multi-layer cell constructs are presented. These cell printing experiments not only demonstrate near 100% viability, they also are the first steps toward using BioLP to create heterogeneous 3-dimensional constructs for use in tissue engineering applications.

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A technique by which to print patterns and multilayers of scaffolding and living cells could be used in tissue engineering to fabricate tissue constructs with cells, materials, and chemical diversity at the micron scale. We describe here studies using a laser forward transfer technology to print single-layer patterns of pluripotent murine embryonal carcinoma cells. This report focuses on verifying cell viability and functionality as well as the ability to differentiate cells after laser transfer. We find that when cells are printed onto model tissue scaffolding such as a layer of hydrogel, greater than 95% of the cells survive the transfer process and remain viable. In addition, alkaline comet assays were performed on transferred cells, showing minimal single-strand DNA damage from potential ultraviolet-cell interaction. We also find that laser-transferred cells express microtubular associated protein 2 after retinoic acid stimulus and myosin heavy chain protein after dimethyl sulfoxide stimulus, indicating successful neural and muscular pathway differentiation. These studies provide a foundation so that laser printing may next be used to build heterogeneous multilayer cellular structures, enabling cell growth and differentiation in heterogeneous three-dimensional environments to be uniquely studied.