Prof. Abraham Shanzer: Faster and more powerful molecular locks could serve as the smallest ID tags, providing the ultimate defense against forgery.When you withdraw money from an ATM you must enter a personal identification number. It’s no good entering the numbers in any old order, the machine’s electronic logic gates dictate that you must enter them in the correct pre-set sequence to make a successful withdrawal. Now a team of Israeli scientists has created a molecule that can function as an ultra-miniaturized version of a keypad locking mechanism.

The molecular keypad lock, the first of its kind, was developed by scientists at the Weizmann Institute of Science in Rehovot. It operates similarly to the electronic locks on today’s ATM machines, but uses a molecule in place of electrical circuits. The result is a lock that offers much greater security than simple molecular logic gates.

The molecule, synthesized in the lab of Prof. Abraham Shanzer, an organic chemist who has worked as a professor at the Weizmann for 30 years, is composed of two smaller linked units – fluorescent probes – separated by a molecular chain to which iron can bind. One of these probes can shine bright fluorescent blue and the other fluorescent green, but only if the surrounding conditions are right. These conditions are the keypad inputs: rather than the electric pulses of an electronic keypad, they consist of iron ions, acids, bases, and ultraviolet light. Shanzer’s latest research on the molecular keypad was published in the Journal of the American Chemical Society (JACS) in December.

Shanzer and his team of scientists, which include Dr. David Margulies, Dr. Galina Melman and Dr. Clifford Felder, have been working in the field of molecular science for many years. In past research, Shanzer showed that molecules can be used as logic gates, similar to those that form the basis of computer operations. Unlike electronic logic gates, however, where electrical switches turn on and off, Shanzer’s molecules use various combinations of chemical and light inputs, switching between colors and light intensities to perform mathematical calculations.

The challenge the scientists faced in creating the functional 12-key prototype keypad lock was in generating sequences that can be distinguished one from another. On a calculator, entering the sequence 2+3+4 will yield the same result as 3+4+2, but a keypad lock set to one password (234) will not open for the other (342). “The numbers are not relevant, the order is,” Shanzer told ISRAEL21c.

The scientists found that by controlling the opening rate of the logic gate within the reaction time frame, they were able to produce different, distinguishable outputs, depending on the input order. By adding light energy, which also influences the glow of the molecules, they were able to produce a molecule-size device that lights up only when the correct chemical ‘passwords’ are introduced.

At present, the molecule-size keypad lock developed by Shanzer and his team, requires nine minutes to operate, and cannot use longer passwords. While this makes it inappropriate for present use, Shanzer believes the keypad could lead to a new level of safeguards in the war against forgery, or in protection of secret information.

“Faster and more powerful molecular locks could serve as the smallest ID tags, providing the ultimate defense against forgery,” explains Shanzer.

Further ahead, the technology could also be used to design smart diagnostic equipment that can detect the release of biological molecules in the body that could indicate disease or exposure to chemical or biological weapons, such as Sarin. “The appearance of nitrate oxide in the body, for example, could show us that a patient was getting very close to a heart attack,” Shanzer explains. “If molecules appear in a certain order, we know something is wrong.

“This is still many years away, however,” he adds.