RESEARCH: Sailor Research Group at UCSD

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Summary
We synthesize nanomaterials and study their chemistry, electrochemistry, and optical properties. Our emphasis is on nanophase silicon-based materials. Current project topics: •Silicon-based nanodevices for in-vivo detection and treatment of cancerous tumors and eye-related diseases •"Smart Dust" --Low-power distributed sensors for environmental toxins and pollutants based on porous Si photonic crystals •Label-free molecular biosensors based on thin film optical interferometry in porous thin films •Cell-based biosensors and bioreactors incorporating bacterial or mammalian cells with porous photonic crystals •Digital microfluidics using magnetic porous Si photonic crystals •Superparamagnetic iron oxide nanoparticles for in-vivo imaging, diagnostics and treatment of cancer


Current Projects
Magnetic Iron Oxide Nanoworms for Tumor Targeting and Imaging. These nano-worms are made of magnetic iron oxide (magnetite) coated with a polymer. The wormlike structure and a speciallized coating allows these nanodevices to find and attach to tumors. Photos: Ji-Ho Park	Engineering Multifunctional Nanoparticles
	NIH-Bioengineering Research Partnerships, NIH CCNE Nanotechnology in Cancer Center, the Moores UCSD Cancer Center and the UCSD NanoTUMOR Center, supported by NIH grant U54 CA 119335r
	The goal of this project is to synthesize new nanomaterials that can be used to allow the early diagnosis and effective treatment of cancer. We are engineering multifunctional nanoparticles that will exploit biological processes to guide the targeting, self-assembly, and remote actuation of these materials to treat tumors in mouse models of cancer. The multidisciplinary team is led by MIT Bioengineering professor Dr. Sangeeta Bhatia, and it also includes tumor biologist Dr. Erkki Ruoslahti of the Burnham Institute at UC Santa Barbara. Publications: Park, J.-H.; Maltzahn, G. v.; Zhang, L.; Derfus, A. M.; Simberg, D.; Harris, T. J.; Bhatia, S. N.; Ruoslahti, E.; Sailor, M. J., "Systematic Surface Engineering of Magnetic Nanoworms for in vivo Tumor Targeting." Small 2009, 5, (6), 694-700. Park, J.-H. et al. Magnetic Iron Oxide Nanoworms for Tumor Targeting and Imaging. Adv. Mater. 2008, 20, 1630-1635. Simberg, D. et al. Biomimetic amplification of nanoparticle homing to tumors. Proc. Natl. Acad. Sci. U. S. A., 2007, 104, 932-936. Maltzahn, G.v. et al. Nanoparticle Self-Assembly Directed by Antagonistic Kinase and Phosphatase Activities. Adv. Mater., 2007, 19, 3579–3583. Maltzahn, G.v. et al. Nanoparticle Self-Assembly Gated by Logical Proteolytic Triggers. J. Am. Chem. Soc. 2007, 129, 6064-6065. Researchers: Matt Kinsella

Luminescent porous silicon nanoparticles in a vial. The vial is being illuminated with an ultraviolet ("black") light, and the bright red-orange photoluminescence is observed. Prepared from high-purity silicon wafers, these nanoparticles provide a non-toxic and biodegradable alternative to conventional quantum dots for drug delivery and medical diagnostic applications. Photo Credit: Luo Gu, Ji-Ho Park, UCSD	Targeted in Vivo Microplatform for Nano Devices
	NIH CCNE Nanotechnology in Cancer Center, the Moores UCSD Cancer Center and the UCSD NanoTUMOR Center http://cancer.ucsd.edu/aboutus/news/ccbrowser/ccbrowser.asp
	The goal of this project is to construct non-toxic, environmentally and systemically benign devices that are equipped with nano-sized features capable of homing into cancerous tumors in the body and performing various tasks. These tasks include detecting, identifying, and imaging a tumor, performing measurements on it, and delivering therapies. The system is based on nanostructured porous particles composed primarily of silicon or silicon oxides. The mother ship design concept and silicon-based scaffolding were chosen for a number of reasons: (1) The unique engineering features such as optical reporting properties; (2) high-capacity nano-porous carrier structure with a high degree of biocompatibility and bioresorbability; (3) Ability of the nanoparticles to be modified with tumor-specific vascular homing peptides that are not taken up by the reticuloendothelial system; (4) The mother ship platform can accomodate nanoparticles, drugs, and imaging agents in a controlled fashion. Publications: Park, J.-H.; Gu, L.; Maltzahn, G. v.; Ruoslahti, E.; Bhatia, S. N.; Sailor, M. J., "Biodegradable luminescent porous silicon nanoparticles for in vivo applications." Nature Mater. 2009, 8, 331-336. Researchers: Luo Gu, Shalini Ananda, Sara Alvarez, Jennifer S. Park, Jennifer Andrew, Elizabeth Wu.

Single magnetic porous silicon microparticle delivers a nanogram payload. Delivery of horseradish peroxidase (contained in microparticle indicated by the arrow) to a droplet containing a colorimetric enzymatic substrate is accomplished by manipulation of the particle using a small magnet. This methodology presents an alternative to channel-based microfluidic systems. Thomas, J. C., Pacholski, C. & Sailor, M. J. "Delivery of Nanogram Payloads Using Magnetic Porous Silicon Microcarriers." Lab Chip 2006, 6, 782 - 787.	Smart Dust: Manipulation of Chemicals, Biochemicals, and Cells with Porous Si Chaperones
	NSF-Division of Materials Research (NSF-DMR 0452579), NIH CCNE Nanotechnology in Cancer Center, the Moores UCSD Cancer Center and the UCSD NanoTUMOR Center
	One of the challenges faced by nanotechnology involves the manipulation of minescule amounts of liquid. There is an increasing need to do this, as the required time and cost of many medical and environmental analyses is directly proportional to sample volume. Fifteen years ago, the concept of the "lab on a chip" evolved as a marriage of the methods used by analytical chemists and microbiologists with the tools developed in the semiconductor industry for microfabrication. In the world of microfluidics, the bucket is often preferable to the pipe; as the sample volume becomes smaller, the number of molecules that stick to the insides of a microchannel becomes a significant fraction of the total molecules in the sample. This problem spawned the so-called "lab-on-a-drop" concept. A sphere has the lowest ratio of surface area to volume, and if a droplet containing the sample of interest can be manipulated without it coming into contact with the walls of its container, the amount of material lost can be minimized. In this project, we use micron-sized, nanostructured particles of porous Si as manipulators. The particles can carry a nano payload or surround a much larger liquid droplet. The particles contain superparamagnetic iron oxide, and application of a magnetic field allows them to be manipulated. The method provides a general means for manipulating small volumes of liquids without a microfluidic container or use of a pump. References: Dorvee, J. R.; Sailor, M. J.; Miskelly, G. M. "Digital microfluidics and delivery of molecular payloads with magnetic porous silicon chaperones," Dalton Trans. 2008, 721 Thomas, J. C., Pacholski, C. & Sailor, M. J. "Delivery of Nanogram Payloads Using Magnetic Porous Silicon Microcarriers." Lab Chip 2006, 6, 782 - 787. Park, J.-H. et al. "Local Heating of Discrete Droplets Using Magnetic Porous Silicon-Based Photonic Crystals." J. Am. Chem. Soc. 2006, 128 7938-7946. Dorvee, J. R., Derfus, A. M., Bhatia, S. N. & Sailor, M. J. "Manipulation of liquid droplets using amphiphilic, magnetic 1-D photonic crystal chaperones." Nature Mater. 2004, 3, 896-899. Researchers: Chia-Chen Wu.

Porous Si photonic crystal chemical agent sensors. Roughly the size of the diameter of a human hair, these particles change color in the presence of volatile organic compounds. Photo credit: Anne Ruminski.	Smart Dust: Nanosensors Using Porous Photonic Crystals
	Elintrix, US Army, Rhevision, DTRA
	The goals of this project are to: (1) develop low-power, sensitive and specific sensors for chemical and biological agents using porous nanomaterials, (2) develop the capability to correct for changes in relative humidity, temperature, and other environmental variables in a low-power, portable package, and (3) demonstrate integratability with conventional electronics. In this project we have: •Constructed wireless and fiber-based remote sensors for chemical warfare agents, TICs, and pollutants •Developed "Smart Dust," photonic crystals that detect the presence of molecules as a shift in their characteristic photonic resonance (color change) •Invented Reflective Interferometric Fourier Transform Spectroscopy (RIFTS) that provides automatic drift compensation at the materials level King, B. H.; Ruminski, A. M.; Snyder, J. L.; Sailor, M. J., "Optical fiber-mounted porous silicon photonic crystals for sensing of organic vapor breakthrough in activated carbon," Adv. Mater. 2007, 19, 4530. Sailor, M. J.; Link, J. R., "Smart Dust: nanostructured devices in a grain of sand." Chem. Commun. 2005, 1375-1383. Pacholski, C.; Sartor, M.; Sailor, M. J.; Cunin, F.; Miskelly, G. M., "Biosensing using porous silicon double-layer interferometers: reflective interferometric Fourier transform spectroscopy." J. Am. Chem. Soc. 2005, 127, 11636-11645. Researchers: Anne Ruminski, Brian King, Adrian Garcia-Sega, Travis Wong.

Waveform encoded into a porous Si photonic crystal. The cross-sectional electron microscope image displays the porous nanostructure that was generated using the current-time waveform depicted at the left. Image credit: Shawn O. Meade.	Spectrally Barcoded Microparticles
	NSF DMR-0806859
	The goal of this project is to construct encoded particles that act as robust, non-toxic taggants. The tags are in the form of microscopic particles containing an elaborate nanostructure that is programmed during electrochemical synthesis to display a complex reflectivity spectrum, referred to as a “Spectral Barcode." The reflectivity spectrum can be decoded using simple, low-power optical spectrometers. We are developing these materials for various applications in high throughput screening and encoded bead-based assays. References: 1. Meade, S. O.; Yoon, M. S.; Ahn, K. H.; Sailor, M. J., "Porous silicon photonic crystals as encoded microcarriers." Adv. Mater. 2004, 16, (20), 1811-1814. 2. Sailor, M. J.; Link, J. R., "Smart Dust: nanostructured devices in a grain of sand." JCS Chem. Commun. 2005, 1375-1383. 3. Meade, S. O.; Sailor, M. J., "Microfabrication of freestanding porous silicon particles containing spectral barcodes." phys. stat. sol. (RRL) 2007, 1, (2), R71–R73. Researchers: Michelle Chen

A porous silicon double-layer interferometer contains two porous layers: one with large pores on top of one with small pores. These layers can discriminate molecules based on size, and the optical response of the film provides a self-compensating sensing function. Photo credit: Claudia Pacholski	New functionalized hybrid systems for drug delivery
	NSF-Europe Materials Collaboration (NSF-DMR-0806859)
	The objective of the project is to develop a vehicle for administration of drugs whose release characteristics can be controlled by intelligent design at the nanoscale. The approach involves infusion of a molecule into a chemically modified matrix of nanocrystalline porous Si or SiO2. Drugs such as the anti-inflammatory dexamethasone, the antibiotic vancomycin, and the analgesic ibuprofen are being incorporated into microscopic particles of porous Si. The high surface area and free volume in porous Si films allows the loading of a large amount of drug. Chemistries to cap the pores with noble metals, polymers, proteins, and silica derived from silanols are being developed, to allow for the slow release of drug under appropriate physiological conditions. The work encompasses new methods of trapping molecules into porous nanostructures, and new methods of monitoring the porous nanostructures using the optical properties of the materials. In particular, we have developed one-dimensional photonic crystals whose spectral signatures can report on the amount or type of drug contained within. Our European partners for this effort are Drs. Bernard Coq, Jean-Marie Devoisselle and Frederique Cunin of the CNRS Laboratoire de Matériaux Catalytiques et Catalyse en Chimie Organique in Montpellier, France. The Montpellier lab has played a major role in the development and commercialization of liposome-based drug delivery materials. The collaboration involves significant student exchange; one of the UCSD student researchers spends approximately 3 months in Montpellier each year. Orosco, M. M.; Pacholski, C.; Sailor, M. J., "Real-time monitoring of enzyme activity in a mesoporous silicon double layer." Nature Nanotech. 2009, 4, 255 - 258. Wu, J.; Sailor, M. J., "Chitosan Hydrogel-Capped Porous SiO2 as a pH-Responsive Nano-Valve for Triggered Release of Insulin." Adv. Funct. Mater. 2009, 19, 733–741. Schwartz, M. P.; Cunin, F.; Cheung, R. W.; Sailor, M. J., "Chemical modification of silicon surfaces for biological applications." Phys. Status Solidi A-Appl. Mat. 2005, 202, (8), 1380-1384. Pacholski, C.; Sartor, M.; Sailor, M. J.; Cunin, F.; Miskelly, G. M., "Biosensing using porous silicon double-layer interferometers: reflective interferometric Fourier transform spectroscopy." J. Am. Chem. Soc. 2005, 127, 11636-11645. Researchers: Michelle Chen, Chia-Chen Wu.

Human epithelial (HeLa) cells on a "Smart Petri Dish." These cells are used to study cancer, and they are living on a nanostructure made from silicon and plastic known as a photonic crystal. The colors observed can be used to monitor the physiological status of the cells. Photo credit: Sara Alvarez and Austin Derfus	The "Smart Petri Dish:" Live Cells Grown on Nanostructured Porous Silicon Sensors
	La Jolla Interfaces in Science program, funded by the Burroughs Wellcome Fund, Department of Education, Graduate Assistance in Areas of National Need (GANN) program (P200A030163), the San Diego Fellowship Program, NSF-Division of Materials Research (NSF-DMR 0452579)
	This project is a multidisciplinary effort involving our group, Lin Chao in the Biology Division at the University of California, San Diego and Sangeeta Bhatia at the Massachusetts Institute of Technology. The objective of this effort is to construct photonic materials capable of monitoring pathogens and viruses in air and in water. In our early work we focused on a soil bacteria, Pseudomonas syringae phaseolicola, and mammalian hepatocyte cells. However, the concepts we have developed define a general method for remote detection of all cell types, including human cell lines (see left image). We have also explored the use of this method for detection of viruses and as a potential method for studying virus propagation in bacterial colonies. Our group focuses on development of the functional photonic materials, which involves chemically modifying nanocrystalline porous Si and polymers templated from this material. Lin Chao and Sangeeta Bhatia provide the expertise in bacterial and mammalian cell biology, respectively. In order to provide specific indicators of cell type, we immobilize adhesion proteins, sugars, and other molecules to improve cell sticking. Researchers: Chia-Chen Wu, Sara Alvarez

Matt Snedaeker with the UAV containing his sensor, just prior to launch. Jeju Island, Korea. Photo: Hung Nguyen	Remote Chemical Sensor on an Airborne Platform
	NSF-CAPMEX
	The work constitutes a collaboration between the Sailor Labs in the Department of Chemistry and Biochemistry at UCSD and V. Ramanathan at the Scripps Institute of Oceanography (SIO) involving the construction and deployment of chemical sensors based on porous silicon photonic crystals. The sensors will be integrated with an Unmanned Aerial Vehicle (UAV) for real-time exposure assessment. The three main goals of the projectare to (1) Construct a sensor to detect a VOCs and oxidants as two separate classes; (2) Integrate the sensor and a fiber-optic based spectrometer onto the SIO UAV; and (3) acquire data both during and after flight to validate the sensitivity and specificity of the sensor. Researchers: Matthew Snedaeker, Adrian Garcia-Sega, Travis Wong, Anne Ruminski