MIT creates tiny backpacks for cells

November 06, 2008

Polymer patches could ferry drugs, assist in cancer diagnosis

CAMBRIDGE, Mass. -- MIT engineers have outfitted cells with tiny "backpacks" that could allow them to deliver chemotherapy agents, diagnose tumors or become building blocks for tissue engineering.

Michael Rubner, director of MIT's Center for Materials Science and Engineering and senior author of a paper on the work that appeared online in Nano Letters on Nov. 5, said he believes this is the first time anyone has attached such a synthetic patch to a cell.

The polymer backpacks allow researchers to use cells to ferry tiny cargoes and manipulate their movements using magnetic fields. Since each patch covers only a small portion of the cell surface, it does not interfere with the cell's normal functions or prevent it from interacting with the external environment.

"The goal is to perturb the cell as little as possible," said Robert Cohen, the St. Laurent Professor of Chemical Engineering at MIT and an author of the paper.

The researchers worked with B and T cells, two types of immune cells that can home to various tissues in the body, including tumors, infection sites, and lymphoid tissues - a trait that could be exploited to achieve targeted drug or vaccine delivery.

"The idea is that we use cells as vectors to carry materials to tumors, infection sites or other tissue sites," said Darrell Irvine, an author of the paper and associate professor of materials science and engineering and biological engineering.

Cellular backpacks carrying chemotherapy agents could target tumor cells, while cells equipped with patches carrying imaging agents could help identify tumors by binding to protein markers expressed by cancer cells.

Another possible application is in tissue engineering. Patches could be designed that allow researchers to align cells in a certain pattern, eliminating the need for a tissue scaffold.

The polymer patch system consists of three layers, each with a different function, stacked onto a surface. The bottom layer tethers the polymer to the surface, the middle layer contains the payload, and the top layer serves as a "hook" that catches and binds cells.

Once the layers are set up, cells enter the system and flow across the surface, getting stuck on the polymer hooks. The patch is then detached from the surface by simply lowering the temperature, and the cells float away, with backpacks attached.

"The rest of the cell is untouched and able to interact with the environment," said Albert Swiston, lead author of the paper and a graduate student in materials science and engineering.

The researchers found that T cells with backpacks were able to perform their normal functions, including migrating across a surface, just as they would without anything attached.

By loading the backpacks with magnetic nanoparticles, the researchers can control the cells' movement with a magnetic field.

Because the polymer synthesis and assembly takes place before the patches are attached to cells, there is plenty of opportunity to tweak the process to improve the polymers' effectiveness and ensure they won't be toxic to cells, the researchers say.

Massachusetts Institute of Technology

---

---

	Materials Science and Engineering: An Introduction by William D. Callister (Author) Building on the extraordinary success of six best-selling editions, Bill Callister's new Seventh Edition of MATERIALS SCIENCE AND ENGINEERING: AN INTRODUCTION continues to promote student understanding of the three primary types of materials (metals, ceramics, and polymers) and composites, as well as the relationships that exist between the structural elements of materials and their properties.
	Fundamentals of Materials Science and Engineering: An Integrated Approach by William D. Callister (Author), David G. Rethwisch (Author) Callister and Rethwisch's Fundamentals of Materials Science and Engineering, 4th Edition continues to take the integrated approach to the organization of topics. That is, one specific structure, characteristic, or property type at a time is discussed for all three basic material types — metals, ceramics, and polymeric materials. This order of presentation allows for the early introduction of non-metals and supports the engineer's role in choosing materials based upon their characteristics. Also discussed are new, cutting-edge materials. Using clear, concise terminology that is familiar to students, Fundamentals presents material at an appropriate level for both student comprehension and instructors who may not have a materials background.
	Introduction to Materials Science for Engineers (7th Edition) by James F. Shackelford (Author) This book provides balanced, current treatment of the full spectrum of engineering materials, covering all the physical properties, applications and relevant properties associated with engineering materials. The book explores all of major categories of materials while offering detailed examinations of a wide range of new materials with high-tech applications. The reader is treated to state-of-the-art computer generated crystal structure illustrations, offering the most technically precise and visually realistic illustrations available. The book includes over 350 exercises with sample problems to provide guidance. Materials for Engineering, Atomic Bonding, Crystal Structure and Defects, Diffusion, Mechanical Behavior, Thermal Behavior, Failure Analysis & Prevention. Phase Diagrams, Heat...
	Foundations of Materials Science and Engineering by William Smith (Author), Javad Hashemi (Author) Smith/Hashemi's Foundations of Materials Science and Engineering, 5/e provides an eminently readable and understandable overview of engineering materials for undergraduate students. This edition offers a fully revised chemistry chapter and a new chapter on biomaterials as well as a new taxonomy for homework problems that will help students and instructors gauge and set goals for student learning. Through concise explanations, numerous worked-out examples, a wealth of illustrations & photos, and a brand new set of online resources, the new edition provides the most student-friendly introduction to the science & engineering of materials. The extensive media package available with the text provides Virtual Labs, tutorials, and animations, as well as image files, case studies, FE Exam review...
	The Science and Engineering of Materials by Donald R. Askeland (Author), Pradeep P. Fulay (Author), Wendelin J. Wright (Author) This text provides an understanding of the relationship between structure, processing, and properties of materials. By selecting the appropriate topics from this wealth of material, instructors can emphasize materials, provide a general overview, concentrate on mechanical behavior, or focus on physical properties. Since the book has more material than is needed for a one-semester course, students will also have a useful reference for subsequent courses in manufacturing, materials, design, or materials selection.
	Materials Science and Engineering: An Introduction 7th Seventh Edition by William D. Callister Jr. (Author)
	Materials and Design, Second Edition: The Art and Science of Material Selection in Product Design by Michael F. Ashby (Author), Kara Johnson (Author) Materials are the stuff of design. From the very beginning of human history, materials have been taken from the natural world and shaped, modified, and adapted for everything from primitive tools to modern electronics. This renowned book by noted materials engineering author Mike Ashby and Industrial designer, Kara Johnson, explores the role of materials and materials processing in product design, with a particular emphasis on creating both desired aesthetics and functionality. The new edition will feature even more of the highly useful "materials profiles," that give critical design, processing, performance and applications criteria for each material in question. The reader will find information ranging from the generic and commercial names of each material, its physical and mechanical...
	Elements of Materials Science and Engineering (6th Edition) by L. H. Van Vlack (Author)
	Materials Science of Thin Films, Second Edition by Milton Ohring (Author) This is the first book that can be considered a textbook on thin film science, complete with exercises at the end of each chapter. Ohring has contributed many highly regarded reference books to the AP list, including Reliability and Failure of Electronic Materials and the Engineering Science of Thin Films. The knowledge base is intended for science and engineering students in advanced undergraduate or first-year graduate level courses on thin films and scientists and engineers who are entering or require an overview of the field. Since 1992, when the book was first published, the field of thin films has expanded tremendously, especially with regard to technological applications. The second edition will bring the book up-to-date with regard to these advances. Most chapters have...
	Materials 3e North American Edition w/Online Testing: Materials North American Edition w/Online Testing: Materials - North American Edition, Second ... engineering, science, processing and design by Michael F. Ashby (Author), Hugh Shercliff (Author), David Cebon (Author) This is the essential materials engineering text and resource for students developing skills and understanding of materials properties and selection for engineering applications. Taking a unique design- led approach that is broader in scope than other texts, Materials 2e meets the curriculum needs of a wide variety of courses in the materials and design field, including introduction to materials science and engineering, engineering materials, materials selection and processing, and materials in design. This new edition retains its design-led focus and strong emphasis on visual communication while expanding its treatment of crystallography and phase diagrams by use of "Guided Learning" sections to fully meet the needs of instructors teaching an introductory course in materials. KEY...