Carbon nanotubes (CNTs) have had a significant impact on materials science since their discovery in 1991. Recently, they have also entered the fields of molecular biology, biomedicine, and bioanalytical chemistry. Their unique combination of high chemical stability and exceptional optical and electrical properties, along with their high surface-to-volume ratio and aspect ratio, makes them ideal candidates for use in biosensors and as "nanosyringes" for drug or biological marker delivery into living cells. Over the past few years, high-quality CNTs have become commercially available, stimulating the development of biology-related CNT applications. However, the purity, agglomeration state, and length and diameter distribution of the tubes can significantly affect their dispersability and surface properties. Therefore, reliable protocols that include detailed information on the used nanotubes are needed to ensure consistency across different fields. This book is organized into five parts. The first part focuses on CNT chemical functionalization approaches, which are essential for overcoming the hydrophobic nature of CNTs and improving their solubility and biocompatibility. The second part is devoted to toxicity studies of CNTs, highlighting their ability to be taken up by cells and traffic through cellular barriers. The third part covers the intracellular trafficking of functionalized CNTs, using three different methodologies. Part 4 deals with modified CNT networks as scaffolds for cell growth, an area of increasing interest for future therapies and neurochip devices. Finally, Part 5 provides protocols related to CNT-based biosensors, emphasizing amperometric detection principles. One central topic is the use of tube coatings to enhance the selectivity of the sensor response toward specific analytes. The book aims to contribute to the achievement of common standards and help avoid discrepancies in future biology-related CNT studies.Carbon nanotubes (CNTs) have had a significant impact on materials science since their discovery in 1991. Recently, they have also entered the fields of molecular biology, biomedicine, and bioanalytical chemistry. Their unique combination of high chemical stability and exceptional optical and electrical properties, along with their high surface-to-volume ratio and aspect ratio, makes them ideal candidates for use in biosensors and as "nanosyringes" for drug or biological marker delivery into living cells. Over the past few years, high-quality CNTs have become commercially available, stimulating the development of biology-related CNT applications. However, the purity, agglomeration state, and length and diameter distribution of the tubes can significantly affect their dispersability and surface properties. Therefore, reliable protocols that include detailed information on the used nanotubes are needed to ensure consistency across different fields. This book is organized into five parts. The first part focuses on CNT chemical functionalization approaches, which are essential for overcoming the hydrophobic nature of CNTs and improving their solubility and biocompatibility. The second part is devoted to toxicity studies of CNTs, highlighting their ability to be taken up by cells and traffic through cellular barriers. The third part covers the intracellular trafficking of functionalized CNTs, using three different methodologies. Part 4 deals with modified CNT networks as scaffolds for cell growth, an area of increasing interest for future therapies and neurochip devices. Finally, Part 5 provides protocols related to CNT-based biosensors, emphasizing amperometric detection principles. One central topic is the use of tube coatings to enhance the selectivity of the sensor response toward specific analytes. The book aims to contribute to the achievement of common standards and help avoid discrepancies in future biology-related CNT studies.