Increasing threats from infectious diseases, such as SARS (1) and bird flu (2), and bioterrorism (3) necessitate the development of a portable real-time biosensor device for monitoring and analyzing exposure. In D. Schwartz and F. Collins’ Policy Forum (4 May, p. 695), the potential specific fields of collaboration and one area of critical importance, i.e., bioaerosol sampling, were not clearly elucidated or were left with little discussion.
Inhalation of airborne biological agents has been shown to cause many diseases (4). Recently, label-free nanowire has been successfully applied to the real-time detection of biological species in fluids by translating molecular binding events into microelectronic signals via field-effect transistor (FET) (5, 6). This creates a critical and unprecedented bridge between different disciplines. Use of nanowire-based biosensors for airborne exposure will require technology that is able to efficiently translate bioaerosols into hydrosols without damaging their biological integrity. Some technologies have demonstrated the potential to fill this gap, e.g., the electrostatic precipitator, by depositing nanoscale virus particles into the liquids (7). Advances in microfluidic channels (8) have enabled the efficient transport of virus-laden liquids onto specific antibody-coated multiplexed FETs constructed using silicon nanowires. Upon binding an antibody to the target virus, the individual nano-device would trigger an electronic signal implying a change in conductance of the nanowire (5, 6, 9). ECG wireless technology has been widely used in transmitting real-time cardiac data to remote receiving stations (10, 11), e.g., computer and handheld devices. This same technology can be adapted to relay the electronic signal generated by FETs that interconnect with the ECG pre-amplifier. Combining these described technologies holds great promise in continuously monitoring microbial profiles in the air and finding applications toward the scenarios discussed in the Policy Forum. This may lead to the innovation of a device that can show the levels of classified agents in a real-time manner.
Roadblocks still exist. For extremely low concentrations of agents, a large sample of bioaerosol is required, which correspondingly places a significant barrier on the development of a device wearable by humans. Another challenge is that the lifetime of the antibody-coated nano-device might be brief when exposed to environmental conditions, thus limiting their capacity for continuous monitoring. Investigators in different fields often diverge without knowing the preexisting technologies. These comments may hopefully lead to quicker and broader collaborations among investigators interested in meeting environmental exposure challenges.
Maosheng Yao
Department of Chemical Engineering, Environmental Engineering Program, Yale University, New Haven, CT 06520, USA.
Ki H. Chon
Shiqi Zhen
References
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