简介:Capacitances of five types of viruses, adenovirus type 5 (AV5), herpes simplex virus type 1
(HSV1), simian virus 40 (SV40), vaccinia (MVA), and cowpea mosaic virus (CPMV), were compared by
AC capacitance scanning probe简介:Capacitances of five types of viruses, adenovirus type 5 (AV5), herpes simplex virus type 1
(HSV1), simian virus 40 (SV40), vaccinia (MVA), and cowpea mosaic virus (CPMV), were compared by
AC capacitance scanning probe microscopy. This technique, using a Pt-coated AFM tip as an electrode to
probe capacitance of materials between the tip and a bottom electrode, has been applied to study surface
structures of semiconductors and polymers with nanometer spatial resolution; however, biological samples
at the nanoscale have not been explored by this technique yet. Because most biological cells are poor
conductors, this approach to probe electric properties of cells by capacitance is logical. This scanning
probe technique showed that each virus has distinguishable and characteristic capacitance. A series of
control experiments were carried out using mutant viruses to validate the origin of the characteristic
capacitance responses for different viruses. A mutation on the capsid in HSV1 with green fluorescence
proteins increased capacitance from 9 10-6 to 1 10-5 F/cm2 at the frequency of 104 Hz. Herpes simplex
virus type 2 (HSV2) decreased capacitance when its envelope and glycoproteins were chemically extracted.
These control experiments indicate that dielectric properties of capsid proteins and envelope glycoproteins
significantly influence overall dielectric constants of viruses. Because those capsid proteins and glycoproteins
are characteristic of the virus strain, this technique could be applied to detect and identify viruses at the
single viron level using their distinct capacitance spectra as fingerprints without labeling.详细>