Fig 1.
Droplet contact method (DCM) and the binary system based on DNA blocking and translocation.
(a) Definition of the binary system based on the presence of DNA in an aqueous droplet coated with a lipid monolayer. (b) A schematic view of the bilayer lipid membrane (BLM) formed via DCM. (c) The system for DNA transfer among droplets by DNA translocation through αHL nanopores. (d–f) Electrical detection of DNA translocation and determination of the presence of DNA constructs in the droplet. (d) Output 1 (translocation): A single-stranded DNA (ssDNA) is translocated through an αHL nanopore with a short current blockade. (e) Output 0 (blocking): A double-stranded DNA (dsDNA) is not translocated through the αHL nanopore owing to its larger diameter, inducing a long current blockade. (f) Output 0 (No DNA strand): No DNA strand is present for translocation, and thus no current blockade is generated.
Fig 2.
Negative-AND (NAND) operation system based on DNA translocation.
(a) NAND logic gate concept based on αHL nanopores and three types of DNA strands, ADNA, BDNA, and complementary DNA (CDNA) in a droplet network. (b) A schematic table of NAND operations with the DNA structures and nanopore result for each input.
Table 1.
Nucleotide sequences of ADNA, BDNA, and complementary DNA (CDNA).
Table 2.
Free energy of the secondary structures of DNA constructs.
Fig 3.
An overview of the experiment performed to confirm that the desired outputs were obtained.
(a) Schematic view of the experiment. DNA constructs, hybridized in advance, were injected into a droplet. (b) Typical method for channel current signal analysis. (c–f) A schematic view of translocation of the DNA strands present in each input and the current blockade signals produced.
Fig 4.
A schematic view of the four-well chip, the device used for the four-droplet network.
(a) A four-droplet network for Negative-AND operation. Input (1, 0) was selected as an example. The input DNA strands were injected into the input droplets and the CDNA strands were prepared in the operation droplet. (b) An overall view of the 4WC. The electrodes in the wells were connected to a patch-clamp amplifier. (c) The wiring to the four wells. The electrodes were embedded on the bottom of the wells.
Fig 5.
Outputs of the Negative-AND operation in a four-droplet network.
The operation was performed as follows: Collect 10 DNA translocation or blocking events for a single calculation. Measure duration of each blocking event. Differentiate the events into two groups, those greater than 1 s (number of events = a) and those not greater than 1 s (number of events = b). Calculate a–b, and determine the output as: Output 1: a–b < 0 or Output 0: a–b > 0. Standard errors were determined using the output from three operations. (a) input (0, 0): a–b = –8.0 ± 1.2, output = 1. (b) input (0, 1): a–b = –9.3 ± 0.7, output = 1. (c) input (1, 0): a–b = –2.7 ± 2.4, output = 1. (d) input (1, 1): a–b = 1.3 ± 0.7, output = 0.