Semiconducting nanowires have the potential to act as highly sensitive sensors for the detection of pathogenic microorganisms, without the need for a label on the pathogen. Practical miniature sensors would have applications in diagnostics, homeland security and basic research. Current technologies have not been widely adopted for various reasons, including the difficulty of integrating nanoscale devices into practical sensors. Now a team spanning five departments at Yale has developed a new approach to the problem. In a state-of-the-art (CMOS-compatible) system they create miniature, ultra-sensitive sensors that can detect specific unlabelled antibodies at concentrations below 100 femtomolar and are able to monitor the cellular immune response in 'real-time'. A new approach that uses complementary metal oxide semiconductor field effect transistor compatible technology is reported, and demonstrates the specific label-free detection of below 100 femtomolar concentrations of antibodies as well as real-time monitoring of the cellular immune response. Semiconducting nanowires have the potential to function as highly sensitive and selective sensors for the label-free detection of low concentrations of pathogenic microorganisms1,2,3,4,5,6,7,8,9,10. Successful solution-phase nanowire sensing has been demonstrated for ions3, small molecules4, proteins5,6, DNA7 and viruses8; however, ‘bottom-up’ nanowires (or similarly configured carbon nanotubes11) used for these demonstrations require hybrid fabrication schemes12,13, which result in severe integration issues that have hindered widespread application. Alternative ‘top-down’ fabrication methods of nanowire-like devices9,10,14,15,16,17 produce disappointing performance because of process-induced material and device degradation. Here we report an approach that uses complementary metal oxide semiconductor (CMOS) field effect transistor compatible technology and hence demonstrate the specific label-free detection of below 100 femtomolar concentrations of antibodies as well as real-time monitoring of the cellular immune response. This approach eliminates the need for hybrid methods and enables system-scale integration of these sensors with signal processing and information systems. Additionally, the ability to monitor antibody binding and sense the cellular immune response in real time with readily available technology should facilitate widespread diagnostic applications.

/pdf/label-free-immunodetection-with-cmos-compatible-39gztg5mmq.pdf

Label-free immunodetection with CMOS-compatible semiconducting nanowires

http://cau.ac.kr/~jjang14/BioMEMS/Lazcka_BSBE_Pathogen_Detection_Review_2006.pdf

Pathogen detection: a perspective of traditional methods and biosensors.

Atmospheric aerosol particles of biological origin are a very diverse group of biological materials and structures, including microorganisms, dispersal units, fragments and excretions of biological organisms. In recent years, the impact of biological aerosol particles on atmospheric processes has been studied with increasing intensity, and a wealth of new information and insights has been gained. This review outlines the current knowledge on major categories of primary biological aerosol particles (PBAP): bacteria and archaea, fungal spores and fragments, pollen, viruses, algae and cyanobacteria, biological crusts and lichens and others like plant or animal fragments and detritus. We give an overview of sampling methods and physical, chemical and biological techniques for PBAP analysis (cultivation, microscopy, DNA/RNA analysis, chemical tracers, optical and mass spectrometry, etc.). Moreover, we address and summarise the current understanding and open questions concerning the influence of PBAP on the atmosphere and climate, i.e. their optical properties and their ability to act as ice nuclei (IN) or cloud condensation nuclei (CCN). We suggest that the following research activities should be pursued in future studies of atmospheric biological aerosol particles: (1) develop efficient and reliable analytical techniques for the identification and quantification of PBAP; (2) apply advanced and standardised techniques to determine the abundance and diversity of PBAP and their seasonal variation at regional and global scales (atmospheric biogeography); (3) determine the emission rates, optical properties, IN and CCN activity of PBAP in field measurements and laboratory experiments; (4) use field and laboratory data to constrain numerical models of atmospheric transport, transformation and climate effects of PBAP. Keywords: primary biological atmospheric aerosol; climate; cloud condensation nuclei; biology; atmospheric ice nuclei (Published: 22 February 2012) Citation: Tellus B 2012, 64 , 15598, DOI: 10.3402/tellusb.v64i0.15598

https://www.tandfonline.com/doi/pdf/10.3402/tellusb.v64i0.15598

Primary biological aerosol particles in the atmosphere: a review

An overview of foodborne pathogen detection: In the perspective of biosensors

Nanowire field effect transistors (NW-FETs) can serve as ultrasensitive detectors for label-free reagents. The NW-FET sensing mechanism assumes a controlled modification in the local channel electric field created by the binding of charged molecules to the nanowire surface. Careful control of the solution Debye length is critical for unambiguous selective detection of macromolecules. Here we show the appropriate conditions under which the selective binding of macromolecules is accurately sensed with NW-FET sensors.

Importance of the Debye screening length on nanowire field effect transistor sensors.

Recent events have made public health officials acutely aware of the importance of rapidly and accurately detecting acts of bioterrorism. Because bioterrorism is difficult to predict or prevent, reliable platforms to rapidly detect and identify biothreat agents are important to minimize the spread of these agents and to protect the public health. These platforms must not only be sensitive and specific, but must also be able to accurately detect a variety of pathogens, including modified or previously uncharacterized agents, directly from complex sample matrices. Various commercial tests utilizing biochemical, immunological, nucleic acid, and bioluminescence procedures are currently available to identify biological threat agents. Newer tests have also been developed to identify such agents using aptamers, biochips, evanescent wave biosensors, cantilevers, living cells, and other innovative technologies. This review describes these current and developing technologies and considers challenges to rapid, accurate detection of biothreat agents. Although there is no ideal platform, many of these technologies have proved invaluable for the detection and identification of biothreat agents.

Current and Developing Technologies for Monitoring Agents of Bioterrorism and Biowarfare

Rapid detection of Bacillus anthracis spores directly from powders with an evanescent wave fiber-optic biosensor.

A Rapid and Automated Fiber Optic-Based Biosensor Assay for the Detection of Salmonella in Spent Irrigation Water Used in the Sprouting of Sprout Seeds

V.J. H ARWOOD, N .C. D ELAHOYA, R .M. U LRICH, M .F. K RAMER, J .E. W HITLOCK, J .R. G AREY A N D D . V . L I M . 2004. Aims: The genus Enterococcus includes opportunistic pathogens such as E. faecalis and E. faecium, and is also used to assess water quality. Speciation of enterococci in environmental studies can be particularly problematic, therefore protocols for unambiguous, DNA-based analysis could receive wide use in applications ranging from water quality monitoring to microbial source tracking. The goal of this work was to investigate the usefulness of PCR for speciation of putative, biochemically identified E. faecalis and E. faecium isolated from water, faeces and sewage. Methods and Results: Putative enterococci (n ¼ 139) were isolated on mEI agar from dog, human, gull and cow faeces, and from sewage, freshwaters and marine waters. A total of 128 isolates passed standard physiological tests for the genus, and were speciated by the API 20 Strep (APIStrep) biochemical test system. 42AE2% were identified as E. faecalis, and all were confirmed by PCR. 19AE5% were biochemically identified as E. faecium, but only seven were PCR-positive. Conclusions: The 16S rDNA of PCR-positive and PCR-negative E. faecium, including isolates that were inconclusively identified by APIStrep, was sequenced. All formed a monophyletic clade with E. faecium sequences in Genbank. Significance and Impact of the Study: Biochemical identification of E. faecalis agreed 100% with PCR assays, therefore a simple protocol of isolation on mEI followed by PCR should be useful for environmental studies. Discrepancies among biochemical identification, PCR confirmation and DNA sequencing were noted for E. faecium, indicating that routine isolation/identification of E. faecium from environmental samples is a much more difficult task.

Daniel V. Lim

Papers

Current and Developing Technologies for Monitoring Agents of Bioterrorism and Biowarfare

Rapid detection of Bacillus anthracis spores directly from powders with an evanescent wave fiber-optic biosensor.

A Rapid and Automated Fiber Optic-Based Biosensor Assay for the Detection of Salmonella in Spent Irrigation Water Used in the Sprouting of Sprout Seeds

Molecular confirmation of Enterococcus faecalis and E. faecium from clinical, faecal and environmental sources

Rapid PCR confirmation of E. coli O157:H7 after evanescent wave fiber optic biosensor detection