Segments

NeuraSyn can be easily expanded to detect more microbes such as ESKAPE organisms, viruses and fungi, following the same principle of electrochemical detection using aptamers. This would involve generating aptamers against the required targets, using SELEX, modifying the circuit design for the neural chip and training it again with fresh electrical impedance data obtained from Electrochemical Impedance Spectroscopy of the aptamers bound to targets.

The neural chip may be used in any detection/computation system that uses electrical signals as input data. It can be trained to amplify and compute input data and make decisions, relayed to a microcontroller connected to a display. An example would be using it to determine risk of cancer, and cardiovascular and neurodegenerative diseases using electrical impedance changes of aptamer-biomarker binding.

During our integrated human practices we consulted with a doctor from Post Graduate Institute of Medical Education & Research (PGIMER), Chandigarh, microbiologist at Verka Milk Plant, Punjab BioTechnology Incubator, and Krishi Vigyan Kendra (Farmers Science Center), Mohali to understand the protocols and risks with implementation of the NeuraSyn platform. We understood that the current methods of detection of microbes mainly involve culturing, which is slow (takes 2-3 days) or using rapid test kits which have low specificity and high false positives or negatives. Thus, our platform can be used for quick detection of pathogens in human and animal fluids, and contaminants in food or water.

An immediate implementation of NeuraSyn can be to detect bacteria Escherichia coli, and Salmonella typhimurium and fungus Penicillium sp. Thus, it can be used for quick and accurate detection of microbes in the following areas:

• The healthcare field to detect E. coli or S.typhimurium in human fluid samples (blood, urine, sweat etc.).
• In the animal husbandry and fisheries industry to detect S. typhimurium in animal tissues.
• Water quality testing to detect presence of E. coli and S. typhimurium in drinking water sources.
• In the processed food industry to detect presence of E. coli, S. typhimurium and Penicillium sp. in packaged foods.

The NeuraSyn platform can be packaged as a small device containing a test strip (currently one-time use), the neural chip and a microcontroller, a small LCD display and a DC current source (battery). The detailed working of the parts is as follows:

Test Strip	Neural Chip	Microcontroller	Display
3 wells Each well contains aptamers, corresponding to one of 3 microbes on a GO/PANI sheet (electrode) Each well has an electrode cap (on top of which the GO/PANI sheet is placed) connected to the DC power source/battery. Aptamer binds to the target microbe, if present, causing change in impedance. Wires to connect the electrode from each of the 3 wells to the neural chip, carry the electrical signals from the strip to the chip.	Electrodes deposited with metal nanoparticles (Au and Ti) Central region has a glued falcon head with trained neurons creating a circuit in culture The input electrodes carry the signals to the neural circuit The neural circuit analyzes the signals sends output via output electrodes The electrical output signal is sent to the microcontroller via wires.	Negative terminal of the battery is connected to the microcontroller Microcontroller interprets the output signals of the neural chip The signal from the microcontroller is sent to the display, telling it which microbes are present in the sample.	The microbes (if any) present in sample are displayed

Instruction for use

It will work as detection platform in the following manner:

1. A small amount (1-2 mL) of sample is put in each of the three wells of the test strip.
2. The DC power supply is turned on after 5-10 secs
3. The display is read - it shows which of the microbes are present in the sample.
4. The wires from the neural chip to the electrode caps in the test strip are disconnected.
5. The aptamer test strip is discarded properly, after sterilization by boiling/heating.
6. A new test strip lined with aptamers is put and the wires from the neural chip are reconnected with the electrode bottoms of the new strip.

Biosafety, Reusability and Disposal

The platform NeuraSyn is made of non-toxic, eco-friendly biological materials, along with a reusable circuit constructed with metal deposition on electrodes. The media containing neural cells, if they are contaminated or dead, can be safely discarded post steam sterilization if in a laboratory setting. In case this facility is not available, it can be discarded in a zip-lock bag as the cells are not toxic to the environment or living organisms. The used strip containing aptamers has to be discarded after steam sterilization. In case such a facility is not available, it is advisable to boil the strip (in case it contains the bacteria/fungi).

If the neural chip electrodes malfunction, due to breaks in the metal layer, the metal can be deposited again, in a vacuum deposition chamber, after putting a vinyl mask of the circuit on it.

Future Modeling

More advanced PyTorch modeling of the neural chip is required. Simulation of the neural circuit using an ANN model to determine the error rates of the chip has to be performed. A mathematical model of the aptamer-target binding kinetics has to be developed as well.

Future Developments and Testing

To apply the neural chip to other detection platforms or as a computational device, it has to be tested outside lab conditions, on the field. Both the cell lines (N2A and SH-SY5Y) grow best around 35 ℃. Although they are tolerant to temperature changes, they may not thrive at extreme climatic conditions, in desert/arid regions or in arctic, mountain areas. So better cell lines or design may be required to use the neural chip as a universal computational device.

A protocol for washing the microbe-bound to the aptamers needs to be developed. This would enable the test strip to be reusable, bringing down the cost of the platform.

To actually put the platform NeuraSyn in field use, we need extensive testing with field samples. We also need to run trials and compare speed and accuracy with existing methods such as culturing and PCR. The biosafety analysis for on-field application must also be performed by an expert.