Biomolecular Engineering I: Biotechnology

Prelude The early chapters of this book introduce some of the chemicals that are important in human biology. In fact, it is possible to think of the human body as an elaborate bag of chemicals. In the subspecialty called biomolecular engineering (or bio-technology), biomedical engineers examine the changes in chemical components within a biological system and develop methods for modifying these chemicals or their interactions. The concept of introducing chemicals to induce a change in a biological system is familiar; for example, we all have some experience with taking purified chemicals such as acetaminophen or ibuprofen as drugs to relieve pain. But new biological tools now make it possible to consider more complex chemical interventions such as gene therapy (in which a new deoxyribonucleic acid [DNA] sequence is introduced to allow expression of a new genetic activity). The concept of the human body as a bag of chemicals is convenient and comforting. Chemicals can be produced; chemicals can be added or replaced; chemicals are (sometimes) inexpensive. In fact, several decades ago, it was widely reported that the chemicals in the human body were worth about $1. Other investigators estimate the value at closer to $6 million (particularly if the chemicals are purchased from scientific suppliers). Regardless of the dollar value, we often imagine that our bodies can be supplemented, mended, and improved through the addition of chemicals. But the body contains large numbers of many different kinds of chemicals, and as in many complex systems, unexpected patterns can emerge from the sum of the parts. Although the body is composed of chemicals, we don't understand the identity of all of the chemicals in the system, the forces that hold these chemicals together, or the network of interactions that mold the chemicals into an organism. Yet we often attempt to heal with chemicals. This is the challenge of drug delivery (Figure 13.1). Biomolecular engineering includes drug delivery, but also many similar areas of inquiry in which chemical engineering principles are applied to biomedical engineering (BME) problems.