From Cleanroom to Desktop: Emerging Micro-Nanofabrication Technology for Biomedical Applications

This review is motivated by the growing demand for low-cost, easy-to-use, compact-size yet powerful micro-nanofabrication technology to address emerging challenges of fundamental biology and translational medicine in regular laboratory settings. Recent advancements in the field benefit considerably from rapidly expanding material selections, ranging from inorganics to organics and from nanoparticles to self-assembled molecules. Meanwhile a great number of novel methodologies, employing off-the-shelf consumer electronics, intriguing interfacial phenomena, bottom-up self-assembly principles, etc., have been implemented to transit micro-nanofabrication from a cleanroom environment to a desktop setup. Furthermore, the latest application of micro-nanofabrication to emerging biomedical research will be presented in detail, which includes point-of-care diagnostics, on-chip cell culture as well as bio-manipulation. While significant progresses have been made in the rapidly growing field, both apparent and unrevealed roadblocks will need to be addressed in the future. We conclude this review by offering our perspectives on the current technical challenges and future research opportunities

Bioinspired molecular electrets: Bottom-up approach to energy materials and applications

The diversity of life on Earth is made possible through an immense variety of proteins that stems from less than a couple of dozen native amino acids. Is it possible to achieve similar engineering freedom and precision to design electronic materials? What if a handful of nonnative residues with a wide range of characteristics could be rationally placed in sequences to form organic macromolecules with specifically targeted properties and functionalities? Referred to as molecular electrets, dipolar oligomers and polymers composed of non-native aromatic beta-amino acids, anthranilamides (Aa) provide venues for pursuing such possibilities. The electret molecular dipoles play a crucial role in rectifying charge transfer, e.g., enhancing charge separation and suppressing undesired charge recombination, which is essential for photovoltaics, photocatalysis, and other solar-energy applications. A set of a few Aa residues can serve as building blocks for molecular electrets with widely diverse electronic properties, presenting venues for bottom-up designs. We demonstrate how three substituents and structural permutations within an Aa residue widely alter its reduction potential. Paradigms of diversity in electronic properties, originating from a few changes within a basic molecular structure, illustrate the promising potentials of biological inspiration for energy science and engineering

Bioinspired molecular electrets: bottom-up approach to energy materials and applications

© 2015 Society of Photo-Optical Instrumentation Engineers (SPIE). The diversity of life on Earth is made possible through an immense variety of proteins that stems from less than a couple of dozen native amino acids. Is it possible to achieve similar engineering freedom and precision to design electronic materials? What if a handful of nonnative residues with a wide range of characteristics could be rationally placed in sequences to form organic macromolecules with specifically targeted properties and functionalities? Referred to as molecular electrets, dipolar oligomers and polymers composed of non-native aromatic beta-amino acids, anthranilamides (Aa) provide venues for pursuing such possibilities. The electret molecular dipoles play a crucial role in rectifying charge transfer, e.g., enhancing charge separation and suppressing undesired charge recombination, which is essential for photovoltaics, photocatalysis, and other solar-energy applications. A set of a few Aa residues can serve as building blocks for molecular electrets with widely diverse electronic properties, presenting venues for bottom-up designs. We demonstrate how three substituents and structural permutations within an Aa residue widely alter its reduction potential. Paradigms of diversity in electronic properties, originating from a few changes within a basic molecular structure, illustrate the promising potentials of biological inspiration for energy science and engineering

Bioinspired molecular electrets: Bottom-up approach to energy materials and applications

© 2015 Society of Photo-Optical Instrumentation Engineers (SPIE). The diversity of life on Earth is made possible through an immense variety of proteins that stems from less than a couple of dozen native amino acids. Is it possible to achieve similar engineering freedom and precision to design electronic materials? What if a handful of nonnative residues with a wide range of characteristics could be rationally placed in sequences to form organic macromolecules with specifically targeted properties and functionalities? Referred to as molecular electrets, dipolar oligomers and polymers composed of non-native aromatic beta-amino acids, anthranilamides (Aa) provide venues for pursuing such possibilities. The electret molecular dipoles play a crucial role in rectifying charge transfer, e.g., enhancing charge separation and suppressing undesired charge recombination, which is essential for photovoltaics, photocatalysis, and other solar-energy applications. A set of a few Aa residues can serve as building blocks for molecular electrets with widely diverse electronic properties, presenting venues for bottom-up designs. We demonstrate how three substituents and structural permutations within an Aa residue widely alter its reduction potential. Paradigms of diversity in electronic properties, originating from a few changes within a basic molecular structure, illustrate the promising potentials of biological inspiration for energy science and engineering

Revisiting indocyanine green: Effects of serum and physiological temperature on absorption and fluorescence characteristics

Indocyanine green (ICG) remains as the only near infrared dye approved by the FDA. Despite its long history of usage in clinical medicine, a systematic study of the effects of serum proteins at physiologically relevant levels and temperature on absorption and fluorescence characteristics of ICG has been missing. We incubated ICG at concentrations in the range of 0.6-25.8 μM in McCoy's 5a cell culture medium, without and with supplemental fetal bovine serum (FBS) at 5% and 10% levels. Our analyses of absorption and fluorescence spectra indicate that the peak absorbance of ICG associated with its monomeric form increases in the presence of FBS. For example, at ICG concentration of 25.8 μM, the monomer absorbance is increased by nearly 100% in the presence of 10% FBS. Similarly, there is an increase in the relative fluorescence quantum yield of ICG, by as much as nearly 3.5 times in the presence of FBS. When incubated at 37 °C, the presence of FBS in the cell culture medium helps maintain the monomeric absorption of ICG and sustain the increased fluorescence emission. We offer explanations to describe the possible photophysical mechanisms underlying the observed effects and discuss the importance of these results to in-vivo applications of ICG. © 1995-2012 IEEE

Revisiting indocyanine green: Effects of serum and physiological temperature on absorption and fluorescence characteristics

Indocyanine green (ICG) remains as the only near infrared dye approved by the FDA. Despite its long history of usage in clinical medicine, a systematic study of the effects of serum proteins at physiologically relevant levels and temperature on absorption and fluorescence characteristics of ICG has been missing. We incubated ICG at concentrations in the range of 0.6-25.8 μM in McCoy's 5a cell culture medium, without and with supplemental fetal bovine serum (FBS) at 5% and 10% levels. Our analyses of absorption and fluorescence spectra indicate that the peak absorbance of ICG associated with its monomeric form increases in the presence of FBS. For example, at ICG concentration of 25.8 μM, the monomer absorbance is increased by nearly 100% in the presence of 10% FBS. Similarly, there is an increase in the relative fluorescence quantum yield of ICG, by as much as nearly 3.5 times in the presence of FBS. When incubated at 37 °C, the presence of FBS in the cell culture medium helps maintain the monomeric absorption of ICG and sustain the increased fluorescence emission. We offer explanations to describe the possible photophysical mechanisms underlying the observed effects and discuss the importance of these results to in-vivo applications of ICG. © 1995-2012 IEEE

Effects of nanoencapsulation and PEGylation on biodistribution of indocyanine green in healthy mice: quantitative fluorescence imaging and analysis of organs

Baharak Bahmani,1 Christian Y Lytle,2 Ameae M Walker,2 Sharad Gupta,1 Valentine I Vullev,1 Bahman Anvari1 1Department of Bioengineering, 2Division of Biomedical Sciences, University of California, Riverside, CA, USA Abstract: Near-infrared nanoconstructs present a potentially effective platform for site-specific and deep tissue optical imaging and phototherapy. We have engineered a polymeric nanocapsule composed of polyallylamine hydrochloride (PAH) chains cross-linked with sodium phosphate and doped with indocyanine green (ICG) toward such endeavors. The ICG-doped nanocapsules were coated covalently with polyethylene glycol (5000 daltons) through reductive amination. We administrated the constructs by tail vein injection to healthy mice. To characterize the biodistribution of the constructs, we performed in vivo quantitative fluorescence imaging and subsequently analyzed the various extracted organs. Our results suggest that encapsulation of ICG in these PEGylated constructs is an effective approach to prolong the circulation time of ICG and delay its hepatic accumulation. Increased bioavailability of ICG, due to encapsulation, offers the potential of extending the clinical applications of ICG, which are currently limited due to rapid elimination of ICG from the vasculature. Our results also indicate that PAH and ICG-doped nanocapsules (ICG-NCs) are not cytotoxic at the levels used in this study. Keywords: cancer, fluorescent imaging, nanoprobes, near infrared, pharmacokinetics, phototherapy, vascular imagin

Building blocks for bioinspired electrets: Molecular-level approach to materials for energy and electronics

In biology, an immense diversity of protein structural and functional motifs originates from only 20 common proteinogenic native amino acids arranged in various sequences. Is it possible to attain the same diversity in electronic materials based on organic macromolecules composed of non-native residues with different characteristics? This publication describes the design, preparation and characterization of non-native aromatic β-amino acid residues, i.e. derivatives of anthranilic acid, for polyamides that can efficiently mediate hole transfer. Chemical derivatization with three types of substituents at two positions of the aromatic ring allows for adjusting the energy levels of the frontier orbitals of the anthranilamide residues over a range of about one electronvolt. Most importantly, the anthranilamide residues possess permanent electric dipoles, adding to the electronic properties of the bioinspired conjugates they compose, making them molecular electrets