JP2017085974A - Circuit for electroporation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circuit for electroporation that realizes higher viability in sending DNA into a cell to perform transformation.SOLUTION: A circuit 2 for electroporation applies DC pulse to a buffer containing a cell via a pair of load terminals 12, 14 to perform introduction. In electroporation, the circuit 2 includes a signal generator 4 and switching elements Q1, Q2 which perform short circuit the pair of load terminals 12, 14 on turning to an ON-state. The signal generator 4 gives a signal for turning the switching elements Q1, Q2 to an ON-state to the switching elements Q1,Q2 in all or a part of a period when DC pulse is not applied.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a circuit for electroporation in which a DC pulse is applied to a buffer containing cells for introduction.

  Electroporation is transformation by making a microhole in a cell membrane by applying an electric pulse to a cell suspension and sending DNA into the cell. Electroporation is a useful means for expressing a gene of interest in cells or tissues, and has been widely used in many biological species.

  Today, there is a demand for the development of electroporation technology with high introduction efficiency, that is, high viability.

International Publication No. 2015/049897

  An object of the present invention is to provide a circuit for electroporation that realizes higher viability.

  The present invention has been made to achieve the above object. A circuit according to the present invention is a circuit for electroporation in which a DC pulse is applied to a buffer including cells via a pair of load terminals, and is introduced when all or one of the DC pulses is not applied. It is a circuit which short-circuits a pair of load terminals in a section.

  The circuit for electroporation according to the present invention can realize high viability.

FIG. 2 is a circuit diagram of a circuit for electroporation according to the first embodiment and signal waveforms used in the circuit. FIG. 2A is a circuit diagram of a circuit for electroporation according to the second embodiment. FIG. 2B is a diagram of signal waveforms used in the circuit shown in FIG. It is a figure which shows an electroporation apparatus. It is a figure of the waveform of the direct current | flow pulse which an electroporation apparatus generate | occur | produces.

  The electroporator used in the present invention means an electric pulse generator. The electroporator can be purchased from, for example, BioRad, BTX, BEX, Intracel, and Eppendorf. In the present invention, the “electroporation electrode” includes any electrode used in the conventional electroporation method. For example, the electrode which consists of metals, such as platinum, gold | metal | money, aluminum, is mentioned. Usually, the two electrodes are arranged with a gap of about 0.25 mm to about 10 mm, for example about 0.5 mm to about 4 mm or about 1 mm to about 2 mm, and a solution containing cells can be placed in the gap. Electroporation electrodes can be purchased from, for example, BioRad, BTX, BEX, Intracel, and Eppendorf. The solution that can be used for electroporation may be any buffer that allows cells to survive during electroporation.

1. Background to the Embodiment FIG. 3A is a diagram (photograph) showing the entire conventional electroporation apparatus. In the electroporation apparatus shown in FIG. 3a, a platinum block electrode (FIG. 3c) having a gap distance of 1 mm, a length of 10 mm, a width of 3 mm, and a height of 0.5 mm and capable of holding 5 μl of solution between the electrodes is a stereomicroscope (FIG. 3). 3a left) and connected to an electroporator (CUY21EDIT II) (right of FIG. 3a). The size of the platinum block electrode is not limited to this, and the electrode is not limited to platinum. FIG. 3b is an enlarged view of a portion surrounded by a square in FIG. 3a. FIG. 3c is a schematic diagram of a platinum block electrode. The cells are placed in a solution (buffer) in the gap between the electrodes. FIG. 3d is a microscopic image of a fertilized egg placed in the gap between the electrodes.

  FIG. 3e is an example of a direct current pulse applied to a buffer containing cells in electroporation. Here, it is shown that a square pulse of 10 V to 50 V and 3 msec is repeated 3 to 11 times at an interval of 97 msec.

  FIG. 4A shows an example of the output waveform of the electroporator. It shows that a square pulse of 30 V and 3 msec is repeated 5 times in the + direction and 5 times in the − direction at an interval of 97 msec. The voltage change is shown above, and the current change is shown below.

  The following problems can be read from the output waveform shown in FIG. Immediately after the application of the pulse, a long-period voltage change occurs due to residual charge (or reverse reaction) due to a chemical reaction in the buffer. For example, a slight voltage is generated between pulses in the + direction, although no operation such as application is performed from the electroporator. FIG. 4B is an enlarged view of the time axis of FIG. It can be seen that a slight voltage is generated between the load terminals without the pulse potential falling after the + direction pulse is generated.

  The presence of such a long-period voltage change is a factor that lowers the introduction efficiency, that is, viability in electroporation.

  Further, it has been confirmed by experiments that an electromotive force can generate a very small electromotive force before applying a pulse depending on the electrode material and the buffer type.

  The circuit for electroporation according to the embodiment of the present invention eliminates a long-period voltage change that occurs at the load terminal of the electroporator at the time of pulse generation and before and after the pulse generation by a newly provided short circuit, thereby Ability is improved.

2. Embodiments Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

2.1. First Embodiment FIG. 1 is a schematic circuit diagram of a circuit for electroporation according to a first embodiment and a diagram of signal waveforms used in the circuit.

2.1.1. Configuration of First Embodiment A circuit 2 for electroporation according to this embodiment shown in FIG. 1 applies a + voltage to a load 16 and a + power source 6 to apply a + voltage to the load 16. A positive output switch circuit A for the positive power source 6 provided between the positive power source 6 and the output (load) terminal 12, a pair of output (load) terminals 12 and 14 for the negative power source 8 and the load 16. And an output switch circuit B for the power source 8 provided between the power source 8 and the output (load) terminal 14. The “load” here is, for example, a buffer containing cells.

  The circuit 2 for electroporation shown in FIG. 1 further includes a first short-circuit element Q1 and a second short-circuit element that are connected in reverse series between two output (load) terminals 12 and 14. Q2 and the short-circuit element driving power source 10 and the short-circuit element switch circuit C are included. Here, “reverse series” means that the sources and the gates of the first short-circuit element Q1 and the second short-circuit element Q2 are both N-type MOSFETs.

  Furthermore, the circuit 2 for electroporation shown in FIG. 1 includes a signal generator 4. The signal generator 4 generates a signal (signal) for controlling the switching timing of each of the + output switch circuit A, the − output switch circuit B, and the short circuit element switch circuit C.

  The + power supply 6 is a power supply for applying a + DC pulse to the load 16. Due to the switching action of the + output switch circuit A, a plurality of square pulses applied to the load 16 are generated. The switching action of the + output switch circuit A is controlled (determined) by a signal from the signal generator 4 to the + output switch circuit A.

  Similarly, the negative power source 8 is a power source for applying a negative DC pulse to the load 16. A plurality of square pulses applied to the load 16 are generated by the switching action of the output switch circuit B. The switching action of the output switch circuit B is controlled (determined) by a signal from the signal generator 4 to the output switch circuit B.

  The short-circuit element driving power supply 10 and the short-circuit element switch circuit C are connected to each other between a gate and a source at the same time in each of the first short-circuit element Q1 and the second short-circuit element Q2 connected in reverse series. Apply voltage. The short-circuit element driving power source 10 is insulated from other power sources. At the same time, when a predetermined voltage is applied between the gate and the source, the drain and the source of each of the first short-circuit element Q1 and the second short-circuit element Q2 are simultaneously in a low impedance state, that is, turned on. The two output (load) terminals are short-circuited.

  Timing at which the two output (load) terminals are short-circuited, that is, timing at which a predetermined voltage is simultaneously applied between the gate and the source in each of the first short-circuit element Q1 and the second short-circuit element Q2. Is controlled (determined) by a signal from the signal generator 4 to the short-circuit element switch circuit C.

  The short-circuit element driving power source 10 is insulated from other power sources, and the first short-circuit element Q1 and the second short-circuit element Q2 are simultaneously turned on regardless of the polarity of the output (load) terminals 12 and 14. It is a state. That is, when the + terminal 12 of the output (load) terminal is + and the − terminal 14 is −, the first short-circuit element Q1 is turned on in the normal direction. In the second short-circuit element Q2, the polarity is in the reverse direction (that is, the direction in which the drain voltage is − when viewed from the source), but in this case, the polarity is turned on (that is, the resistance state is low). At this time, current does not flow through the parasitic diode.

  When the negative terminal 14 of the output (load) terminal is + and the positive terminal 12 is negative, the second short-circuit element Q2 is turned on in the normal direction. In the first short-circuit element Q1, the polarity is in the reverse direction (that is, the direction in which the drain voltage is − when viewed from the source), but in this case, the polarity is turned on (that is, the resistance state is low). At this time, current does not flow through the parasitic diode.

2.1.2. Operation of the first embodiment 2.1.2.1. Operation of Continuously Applying a + DC Pulse to the Load A signal procedure in the circuit for electroporation according to this embodiment will be described. First, a procedure for continuously applying a positive DC pulse to the load 16 will be described.

Table 1 is a table schematically showing the operation of the circuit 2 for electroporation in which four procedures of “output standby state”, “output transition”, “+ output”, and “output transition” are repeated.
(1) Output standby state The + output switch circuit A and the −output switch circuit B are off.
At this time, when the short-circuit element switch circuit C is turned on, a predetermined voltage is simultaneously applied between the gate and the source in each of the first short-circuit element Q1 and the second short-circuit element Q2, Each of the first short-circuit element Q1 and the second short-circuit element Q2 is turned on, and the two output (load) terminals 12 and 14 are short-circuited.

(2) Output transition All of the + output switch circuit A, the -output switch circuit B, and the short-circuit element switch circuit C are turned off. This time is an extremely short time (several μs), and is a time for preventing a short circuit when each switch circuit (switch element) is switched on / off.

(3) + Output The + output switch circuit A is turned on, and a positive DC pulse is applied to the load 16 from the output (load) terminals 12 and 14. When a negative DC pulse is applied from the output (load) terminals 12 and 14 to the load 16, the negative output switch circuit B is turned on. The + output switch circuit A and the − output switch circuit B should not be in the ON state at the same time.

(4) Output transition All of the + output switch circuit A, the -output switch circuit B, and the short-circuit element switch circuit C are turned off. This time is also an extremely short time (several μs), and is a time for preventing a short circuit when each switch circuit (switch element) is switched on / off.

(5) "(1) Output standby state"
Again, this is a period in which the two output (load) terminals 12, 14 are short-circuited. This short circuit reduces or eliminates long-period voltage changes caused by residual charge due to chemical reactions in the load (buffer).
Thereafter, the procedures of “(2) Output shift”, “(3) + Output”, “(4) Output shift”, “(1) Output standby state”,... Are repeated.

  As described above, “(2) (4) Output transition” provides a delay when each switch circuit (switch element) is turned on / off. This is to prevent a short circuit between the elements.

  The first half of the signal waveform inside the signal generator 4 in the circuit 2 shown in FIG. 1 is the above-described procedure ((1) (2) (3) (4)) in which the positive DC pulse is continuously applied. It is an example of a signal given to a switch circuit (A, B, C) (that is, indicated).

  Further, the first half of the waveform shown at the bottom of FIG. 1 is a plurality of (three) square pulses generated by the above-described procedure of applying the + DC pulse continuously and applied to the load 16.

2.1.2.2. Next, a procedure for continuously applying a negative DC pulse to the load 16 will be described.

  Table 2 is a table schematically showing the operation of the circuit 2 for electroporation in which four procedures of “output standby state”, “output transition”, “−output”, and “output transition” are repeated. Compared with Table 1, the procedure of “(3) -output” is different. The rest of the procedure is the same as in Table 1.

(1) Output standby state The + output switch circuit A and the −output switch circuit B are off.
At this time, when the short-circuit element switch circuit C is turned on, a predetermined voltage is simultaneously applied between the gate and the source in each of the first short-circuit element Q1 and the second short-circuit element Q2, Each of the first short-circuit element Q1 and the second short-circuit element Q2 is turned on, and the two output (load) terminals 12 and 14 are short-circuited.

(2) Output transition All of the + output switch circuit A, the -output switch circuit B, and the short-circuit element switch circuit C are turned off. This time is an extremely short time (several μs), and is a time for preventing a short circuit when each switch circuit (switch element) is switched on / off.

(3)-Output-The output switch circuit B is turned on, and a negative DC pulse is applied to the load 16 from the output (load) terminals 12 and 14. When a + DC pulse is applied from the output (load) terminals 12 and 14 to the load 16, the + output switch circuit A is turned on. The + output switch circuit A and the − output switch circuit B should not be in the ON state at the same time.

(4) Output transition All of the + output switch circuit A, the -output switch circuit B, and the short-circuit element switch circuit C are turned off. This time is also an extremely short time (several μs), and is a time for preventing a short circuit when each switch circuit (switch element) is switched on / off.

(5) "(1) Output standby state"
Again, this is a period in which the two output (load) terminals 12, 14 are short-circuited. This short circuit reduces or eliminates long-period voltage changes caused by residual charge due to chemical reactions in the load (buffer).
Thereafter, the procedures of “(2) output transition”, “(3) -output”, “(4) output transition”, “(1) output standby state”,... Are repeated.

  As described above, “(2) (4) Output transition” provides a delay when each switch circuit (switch element) is turned on / off. This is to prevent a short circuit between the elements.

  In the second half of the signal waveform inside the signal generator 4 in the circuit 2 shown in FIG. 1, in the procedure ((1) (2) (3) (4)) for continuously applying the −DC pulse, It is an example of a signal given to a switch circuit (A, B, C) (that is, indicated).

  Furthermore, the latter half of the waveform shown at the bottom of FIG. 1 is a plurality of (three) square pulses that are generated and applied to the load 16 by the above-described procedure of continuously applying the negative DC pulse.

2.1.2.3. Summary of Operation As described above, in the circuit 2 for electroporation, the two output (load) terminals 12 and 14 are short-circuited in the output standby state, and on the other hand, the square pulse is output at the time of output. It is possible to suppress a long-period voltage change caused by residual charge due to a chemical reaction in the (buffer), thereby improving the viability in electroporation. Note that the two output (load) terminals 12 and 14 need not be short-circuited in all output standby states. That is, even if the two output (load) terminals 12 and 14 are short-circuited only in a part during the output standby state, a long-period voltage change caused by residual charge due to a chemical reaction in the load (buffer) It can be reduced or eliminated considerably.

2.1.3. Modified Example of First Embodiment In the circuit 2 for electroporation according to the first embodiment, the + output switch circuit A and the −output switch circuit B are configured by semiconductor switches that achieve high speed. It is preferable. The + output switch circuit A and the −output switch circuit B may be configured by an amplifier circuit. When configured with an amplifier circuit in this way, it is desirable to output a high impedance when it is off. This is because when the state where the two output (load) terminals 12 and 14 are short-circuited by the first short-circuit element Q1 and the second short-circuit element Q2 is realized, the + output switch circuit A or -output If the switch circuit B has a low impedance output, the + output switch circuit A or the -output switch is selected by a short circuit composed of the first short-circuit element Q1 and the second short-circuit element Q2. This is because a large current flows through the circuit B.

  Further, in the circuit 2 for electroporation according to the first embodiment, by the operation of the signal generator 4, the short-circuit element switch circuit C, the first short-circuit element Q1, and the second short-circuit element Q2, A short circuit between the two output (load) terminals 12 and 14 is realized. Any circuit element capable of realizing a short circuit between the two output (load) terminals 12 and 14 in the “output standby state” can be replaced with these circuit elements.

2.2. Second Embodiment FIG. 2A is a circuit diagram of a circuit for electroporation according to a second embodiment. FIG. 2B is a diagram of signal waveforms used in the circuit shown in FIG.

2.2.1. Configuration of Second Embodiment Unlike the circuit according to the first embodiment, the circuit 2 ′ for electroporation according to the present embodiment shown in FIG. And belongs to a circuit generally called a bridge circuit. A circuit 2 ′ for electroporation shown in FIG. 2A includes a power supply 7 that applies a voltage (+ voltage and −voltage) to a load 16, and a pair of output (load) terminals 12 and 14 for the load 16. , A + output switch circuit 1 provided between the power supply 7 and the output (load) terminal 12, and a −output switch circuit 3 provided between the power supply 7 and the output (load) terminal 14.

  The circuit 2 ′ for electroporation shown in FIG. 2A further includes a first short-circuiting element Q1 and a second short-circuiting element Q1 arranged in anti-series connection between two output (load) terminals 12 and 14. Short-circuit element Q2. Furthermore, the circuit 2 ′ for electroporation shown in FIG. 2A includes a signal generator 5 that generates a signal k, a signal l, a signal m, and a signal n. The signal generator 5 controls the switching timing of each of the + output switch circuit 1 and the −output switch circuit 3 based on the generated signal k and signal n.

  The power source 7 is a power source for applying + and − DC pulses to the load 16. A plurality of square pulses applied to the load 16 are generated by the switching action of the + output switch circuit 1 and the −output switch circuit 3. The switching action of the + output switch circuit 1 and the −output switch circuit 3 is controlled (determined) by signals (signal k, signal n) from the signal generator 5 to the + output switch circuit 1 and the −output switch circuit 3. Is done.

  In addition, the signal generator 5 sends a signal (voltage) to each of the first short-circuit element Q1 and the second short-circuit element Q2 using a signal m and a signal l between the gate and the source. Apply at the timing. Here, if the signal generator 5 applies a predetermined voltage (signal) between the gate and the source at the same time, the drain and the source of each of the first short-circuit element Q1 and the second short-circuit element Q2 are simultaneously formed. The low impedance state (that is, the on state) is established, and the two output (load) terminals are short-circuited.

2.2.2. Operation of the second embodiment 2.2.2.1. Operation of continuously applying + DC pulse to load The signal procedure in the circuit 2 ′ for electroporation according to the present embodiment will be described. First, a procedure for continuously applying a positive DC pulse to the load 16 will be described.

Table 3 is a table schematically showing the operation of the circuit 2 ′ for electroporation by repeating the four steps of “output standby (short circuit)” “+ output transition” “+ output” “short circuit transition”. .
(1) Output standby (short circuit)
Since the signal k and the signal n are OFF, the + output switch circuit 1 and the −output switch circuit 3 are OFF.
At this time, when the signal m and the signal l are turned ON, a predetermined signal (voltage) is simultaneously applied between the gate and the source in each of the first short-circuit element Q1 and the second short-circuit element Q2. Each of the first short-circuit element Q1 and the second short-circuit element Q2 is turned on, and the two output (load) terminals 12 and 14 are short-circuited.

(2) + Output Transition Since the signal k, the signal n, and the signal m are OFF, the + output switch circuit 1, the −output switch circuit 3, and the first short-circuit element Q1 are all turned off. It becomes. This time is an extremely short time (several μs), and is a time for preventing a short circuit when each switch circuit (switch element) is switched on / off.

(3) + Output Since the signal k and the signal l are ON, the + output switch circuit 1 and the second short-circuit element Q2 are turned on, and the output (load) terminals 12 and 14 to the load 16 are + The direct current pulse is applied.

(4) Transition to short circuit Since the signal k, the signal n, and the signal m are OFF, the + output switch circuit 1, the −output switch circuit 3, and the first short-circuit element Q1 are all turned off. Become. This time is also an extremely short time (several μs), and is a time for preventing a short circuit when each switch circuit (switch element) is switched on / off.

(5) "(1) Output standby (short circuit)"
Again, this is a period in which the two output (load) terminals 12, 14 are short-circuited. By this short circuit, the long-period voltage change caused by the residual charge due to the chemical reaction in the load (buffer) disappears.
Thereafter, the procedures of “(2) + output transition”, “(3) + output”, “(4) short circuit transition”, “(1) output standby (short circuit)”,... Are repeated.

  As in the first embodiment, “(2) + output transition, (4) short-circuit transition” causes a delay when each switch circuit (switch element) is turned on / off. 1. A period for turning off the output switch circuit 3 and the first short-circuit element Q1 is provided to prevent a short circuit between the elements.

  The first half of the signal waveform shown in the lower part of FIG. 2B is a signal waveform from the signal generator 5 in the above-described procedure ((1), (2), (3), and (4)). It is an example of a signal given (ie, indicated) as a signal (k, l, n, m).

  Further, the first half portion of the signal waveform shown in the upper part of FIG. 2B is a plurality of (two) square pulses generated by the above-described procedure of continuously applying the + DC pulse and applied to the load 16. .

2.2.2.2. Next, a procedure for continuously applying a negative DC pulse to the load 16 will be described.

Table 4 is a table schematically showing the operation of the circuit 2 ′ for electroporation by repeating the four steps of “output standby (short circuit)”, “−output transition”, “−output”, and “short circuit transition”. .
(1) Output standby (short circuit)
Since the signal k and the signal n are OFF, the + output switch circuit 1 and the −output switch circuit 3 are OFF.
At this time, when the signal m and the signal l are turned ON, a predetermined signal (voltage) is simultaneously applied between the gate and the source in each of the first short-circuit element Q1 and the second short-circuit element Q2. Each of the first short-circuit element Q1 and the second short-circuit element Q2 is turned on, and the two output (load) terminals 12 and 14 are short-circuited.

(5) -Output transition Since the signal k, the signal l, and the signal n are OFF, the + output switch circuit 1, the -output switch circuit 3, and the second short-circuit element Q2 are all OFF. It becomes. This time is an extremely short time (several μs), and is a time for preventing a short circuit when each switch circuit (switch element) is switched on / off.

(6) -Output Since the signal n and the signal m are ON, the output switch circuit 3 and the first short-circuit element Q1 are turned on, and the output (load) terminals 12 and 14 to the load 16- The direct current pulse is applied.

(7) Short-circuit transition Since the signal k, the signal l, and the signal n are OFF, the + output switch circuit 1, the −output switch circuit 3, and the second short-circuit element Q2 are all turned off. Become. This time is also an extremely short time (several μs), and is a time for preventing a short circuit when each switch circuit (switch element) is switched on / off.

(8) "(1) Output standby (short circuit)"
Again, this is a period in which the two output (load) terminals 12, 14 are short-circuited. By this short circuit, the long-period voltage change caused by the residual charge due to the chemical reaction in the load (buffer) disappears.
Thereafter, the procedures of “(5) -output transition”, “(6) -output”, “(7) short-circuit transition”, “(1) output standby (short-circuit)”,... Are repeated.

  As in the first embodiment, “(5) −output transition, (7) short circuit transition” has a delay when each switch circuit (switch element) is turned on / off. 1. A period for turning off the output switch circuit 3 and the second shorting element Q2 is provided to prevent a short circuit between the elements.

  The latter half of the signal waveform shown in the lower part of FIG. 2 (b) is obtained from the signal generator 5 in the above-described procedure ((1) (5) (6) (7)) in which the negative DC pulse is continuously applied. It is an example of a signal given (ie, indicated) as a signal (k, l, n, m).

  Further, the latter half of the signal waveform shown in the upper part of FIG. 2B is a plurality of (two) square pulses generated by the above-described procedure of continuously applying the negative DC pulse and applied to the load 16. .

2.2.2.3. Summary of Operation As described above, in the circuit 2 ′ for electroporation, by short-circuiting between the two output (load) terminals 12 and 14 in the output standby state, while outputting a square pulse at the time of output, It is possible to suppress a long-period voltage change caused by charge remaining due to a chemical reaction in the load (buffer), thereby improving the viability in electroporation. Note that the bridge circuit to which the circuit 2 ′ for electroporation according to the second embodiment belongs is normally used as a power supply output switching circuit (full bridge switching: inverter). The circuit does not have a configuration for output standby (short circuit) in the circuit of the present embodiment, and therefore does not perform output standby (short circuit) operation.

  Also in this embodiment, the two output (load) terminals 12 and 14 do not need to be short-circuited during all output standby. That is, even when the two output (load) terminals 12 and 14 are short-circuited in a part of the output standby state, a long-period voltage change caused by a residual charge due to a chemical reaction in the load (buffer) is considerable. The degree can be reduced or eliminated.

2.2.3. Modified Example of Second Embodiment In the circuit 2 ′ for electroporation according to the second embodiment, the + output switch circuit 1 and the −output switch circuit 3 are the same as in the first embodiment. You may comprise by an amplifier circuit.

  In the circuit 2 ′ for electroporation according to the second embodiment, the + output switch circuit 1 and the −output switch circuit 3, the first short-circuit element Q1, and the second short-circuit element. The position may be interchanged with Q2.

  The first short-circuit element Q1 and the second short-circuit element Q2 are preferably N-type MOSFETs, but may be P-type MOSFETs. At this time, it is preferable to have an ON resistance of at least 1Ω or more.

  The + output switch circuit 1 (or amplifier circuit) and the −output switch circuit 3 (or amplifier circuit) may be TR, FET, IGBT, or the like.

  In the circuit 2 ′ for electroporation according to the second embodiment, two outputs (loads) are generated by the operations of the signal generator 5, the first short-circuit element Q1, and the second short-circuit element Q2. A short circuit between the terminals 12 and 14 is realized. Any circuit element that can realize a short circuit between the two output (load) terminals 12 and 14 during "output standby" can be replaced with these circuit elements.

1, A ... + output switch circuit, 2, 2 '... electroporation circuit, 3, B ...- output switch circuit, 4, 5 ... signal generator, 6. ... + Power source, 7... Power source, 8... − Power source, 10... Short circuit element driving power source, 12... Output (load) terminal (+), 14. Load) terminal (-), 16 ... load, C ... short-circuit element switch circuit, Q1 ... first short-circuit element, Q2 ... second short-circuit element.

Claims (5)

A circuit for electroporation in which a DC pulse is applied to a buffer containing cells via a pair of load terminals for introduction,
A circuit that short-circuits a pair of load terminals in all or part of when no DC pulse is applied. The circuit according to claim 1, wherein the pair of load terminals are not short-circuited in a very short time immediately before the start and a very short time immediately after the end of one DC pulse. A circuit for electroporation in which a DC pulse is applied to a buffer containing cells via a pair of load terminals for introduction,
A signal generator,
Including a switching element that short-circuits the pair of load terminals by being turned on,
The signal generator is a circuit that provides a signal for turning on the switching element to the switching element in all or part of when no DC pulse is applied. 4. The circuit according to claim 3, wherein the signal generator does not emit a signal for turning on the switching element in a very short time immediately before the start and a very short time immediately after the end of one DC pulse. A method of applying a DC pulse to a buffer containing cells via a pair of load terminals, introducing by electroporation,
A method of short-circuiting a pair of load terminals in all or a part when no DC pulse is applied.

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