Method and circuit arrangement for treating biomaterial

[0008] In view of the above, the method of the invention continues the first voltage pulse after termination by at least one additional voltage pulse. It has surprisingly been shown that successful cell treatment can indeed be ensured by continuing the terminated voltage pulse. The additional voltage pulse again exposes the cells to an electrical field, which preferably corresponds to the one generated by the first voltage pulse, so that the suspended cell treatment can be continued, and the desired success can still be achieved. The method according to the invention makes it possible to significantly increase, e.g., in an electroporation, transfection efficiency during the transfection of eukaryotic cells with nucleic acids by continuing or repeating the voltage pulse after a lightning discharge. Thus and advantageously, the method according to the invention can avoid or offset that unpredictable and irreproducible results caused by the randomly arising termination of a voltage pulse. Possible electrical parameters that might trigger a voltage pulse termination are the slope of a voltage drop (flank), a collapsed resistance, current density or the slope of a current rise (flank).

[0011] In another advantageous embodiment of the invention, the same field strength as for the first voltage pulse is preset as the field strength of the additional voltage pulse. This ensures that the cells are treated under constant conditions, and that the additional voltage pulse(s) represent(s) a continuation of the first voltage pulse. This also has a positive impact on the reproducibility of the results.

[0013] In a special embodiment of the invention, a specific pause time is preset between the termination of the first voltage pulse and the generation of the additional voltage pulse, preferably a time of at least 40 μs, more preferably 50 to 600 μs, in particular 100 μs. Specifically setting the pause time makes it possible to adjust the method according to the invention to the type of application, the desired goal and / or the cell type, thereby allowing for an optimization of results. It is generally particularly advantageous here for the pause time to measure at least 40 μs, so that conditions inside the reaction batch can, on the one hand, normalize after the brief current rise and termination event, and, on the other hand, the cells have a short “recovery phase.”

[0014] In one advantageous embodiment of the invention, it is further provided that a total of at least two additional voltage pulses are generated if the preceding additional voltage pulses have been terminated. This embodiment also focuses on the possibility that the additional voltage pulse or several of the additional voltage pulses can be terminated as a result of an electrical parameter exceeding or dropping below a limit. Enabling several repeat attempts further improves the method according to the invention, since the probability of an ultimately flawed test or incomplete treatment can be tangibly reduced. Preferably, the capability to generate 2 or 3 additional voltage pulses is hereby prescribed or set. After termination of the additional voltage pulse, another additional voltage pulse can hence be initiated (2 additional voltage pulses, n=2). If even the latter one is terminated, a third additional voltage pulse is generated (3 additional voltage pulses, n=3). However, this case involves the preset capability of further additional voltage pulses. By contrast, once the preset duration T1 has been reached as a whole, no additional voltage pulses can be initiated.

[0016] In view of the above, the circuit arrangement of the present invention preferably provides at least one controller to monitor the chronological progression of the voltage pulse, said controller controlling at least one continuation of discharge after termination. Introducing an additional controller into the circuit arrangement to monitor the chronological progression of the first (and any additional) voltage pulse(s) makes it possible to calculate the remaining duration of the additional voltage pulse or additional voltage pulses (T2=T1−Tx or T3=T1−(Tx+Ty), etc.) during which, following the termination, a voltage was no longer applied. After a preset or programmable pause, the controller can control the storage device discharge in such a way as to continue it, and thereby complete the discharge time. Hence, the control unit is designed in such a way that it monitors the time elapsed from the beginning of the first voltage pulse and any additional voltage pulses until the termination of the latter, along with the still remaining duration of the additional voltage pulse (T2=T1−Tx or T3=T1−(Tx+Ty), etc.). In this way, the process of discharging the storage device can be controlled by the controller in such a way that the first voltage pulse can be continued or completed, so that the biomaterial can be treated successfully and reproducibly even though one or several voltage pulses have been terminated.

[0018] A preferred embodiment of the invention provides that the controller is a digital signal-processing module, e.g., a DSP. A DSP (digital signal processing) module, e.g., which controls a switching device, makes it possible to monitor the chronological progression of the first voltage pulse or the additional voltage pulses. The DSP module detects the termination of the voltage pulse which is terminated by a control unit. The DSP module calculates the remaining time for which no more voltage was applied. After a programmable pause, the DSP can then control the switching device in such a way as to continue the storage device discharge, e.g., via a control action from the control unit.

During a lightning discharge, the brief rise in power or heat leads to concomitant physical phenomena, such as lightning, cracking and spraying of the solution on the one hand, and irreversible damaging or killing of the cells on the other hand.

Therefore, a lightning discharge generally endangers not only the safety of people and equipment in the vicinity, but also results in a loss of the used biomaterial.

However, depending on the point of termination, the disadvantage of this is that successful treatment is not achieved, e.g., the transfection efficiency is too low.

If the voltage pulse is terminated too early, the corresponding reaction batch must be discarded or can only be used to a very limited extent, even though cell viability has been obtained.