Biomedical subjects

Galina Melman

Publications and source records attributed to Galina Melman.

4 recordsLinked to original sources

PubMed2007

A molecular keypad lock: a photochemical device capable of authorizing password entries.

This paper describes a new concept in the way information can be protected at the molecular scale. By harnessing the principles of molecular Boolean logic, we have designed a molecular device that mimics the operation of an electronic keypad lock, e.g., a common security circuit used for numerous applications, in which access to an object or data is to be restricted to a limited number of persons. What distinguishes this lock from a simple molecular logic gate is the fact that its output signals are dependent not only on the proper combination of the inputs but also on the correct order by which these inputs are introduced. In other words, one needs to know the exact passwords that open this lock. The different password entries are coded by a combination of two chemical and one optical input signals, which can activate, separately, blue or green fluorescence output channels from pyrene or fluorescein fluorophores. The information in each channel is a single-bit light output signal that can be used to authorize a user, to verify authentication of a product, or to initiate a higher process. This development not only opens the way for a new class of molecular decision-making devices but also adds a new dimension of protection to existing defense technologies, such as cryptography and steganography, previously achieved with molecules.

Journal Article↗

PubMed2006

A molecular full-adder and full-subtractor, an additional step toward a moleculator.

Over the past decade, there has been remarkable progress in the development of molecular logic and arithmetic systems, which has brought chemists closer to the realization of a molecular scale calculator (a Moleculator). This paper describes a significant step in this direction. By integrating past and new approaches for molecular logic reconfiguration, we were able to load advanced arithmetic calculations onto a single molecular species. Exchanging chemical inputs, monitoring at several wavelengths simultaneously, as well as using negative logic for the transmittance mode significantly increase the input and output information channels of the processing molecule. Changing the initial state of the processor is an additional approach used for altering the logical output of the device. Finally, introducing degeneracy to the chemical inputs or, alternatively, controlling their interactions to form identical chemical states minimizes the complexity of realizing three-bits addition and subtraction at the molecular scale. Consequently, using a commercially available fluorescein molecule, acid and base chemical inputs, and a simple UV-vis measurement setup, integration of a full-adder and, for the first time, a full-subtractor is now possible within individual molecules.

Anions↗

PubMed2005

Fluorescein as a model molecular calculator with reset capability.

The evolution of molecules capable of performing boolean operations has gone a long way since the inception of the first molecular AND logic gate, followed by other logic functions, such as XOR and INHIBIT, and has reached the stage where these tiny processors execute arithmetic calculations. Molecular logic gates that process a variety of chemical inputs can now be loaded with arrays of logic functions, enabling even a single molecular species to execute distinct algebraic operations: addition and subtraction. However, unlike electronic or optical signals, the accumulation of chemical inputs prevents chemical arithmetic systems from resetting. Consequently, a set of solutions is required to complete even the simplest arithmetic cycle. It has been suggested that these limitations can be overcome by washing off the input signals from solid supports. An alternative approach, which does not require solvent exchange or incorporation of bulk surfaces, is to reset the arithmetic system chemically. Ultimately, this is how some biological systems regenerate. Here we report a highly efficient and exceptionally simple molecular arithmetic system based on a plain fluorescein dye, capable of performing a full scale of elementary addition and subtraction algebraic operations. This system can be reset following each separate arithmetic step. The ability to selectively eradicate chemical inputs brings us closer to the realization of chemical computation.

Computers, Molecular↗

PubMed2004

Chemical input multiplicity facilitates arithmetical processing.

We describe the design and function of a molecular logic system, by which a combinatorial recognition of the input signals is utilized to efficiently process chemically encoded information. Each chemical input can target simultaneously multiple domains on the same molecular platform, resulting in a unique combination of chemical states, each with its characteristic fluorescence output. Simple alteration of the input reagents changes the emitted logic pattern and enables it to perform different algebraic operations between two bits, solely in the fluorescence mode. This system exhibits parallelism in both its chemical inputs and light outputs.

Journal Article↗