A therapeutic keypad lock decoded in drug resistant cancer cells

A molecular keypad lock that displays photodynamic activity when exposed to glutathione (GSH), esterase and light in the given order, is fabricated and its efficacy in drug resistant MCF7 cancer cells is investigated. The first two inputs are common drug resistant tumor markers. GSH reacts with the agent and shifts the absorption wavelength. Esterase separates the quencher from the structure, further activating the agent. After these sequential exposures, the molecular keypad lock is exposed to light and produces cytotoxic singlet oxygen. Among many possible combinations, only one 'key' can activate the agent, and initiate a photodynamic response. Paclitaxel resistant MCF7 cells are selectively killed. This work presents the first ever biological application of small molecular keypad locks.

Homogeneous DNA-only keypad locks enable one-pot assay of multi-inputs

Homogeneous DNA-only keypad locks were built with multi-stranded scalable junction substrates and a series of double-stranded eliminators to differentially process correctly- and wrongly-added DNA inputs, respectively. Unlike conventional strategies that employed solid-phase platforms, one-pot assay of multiple DNA inputs was achieved, showing merits in fabricating complicated information security systems.

Constructing a four-input molecular keypad lock with a multi-stimuli-responsive phthalocyanine

A novel phthalocyanine has been designed and synthesised whose response towards different stimuli can be manipulated to enable it to function as a four-input molecular keypad lock.

Fabrication of prime number checkers based on colorimetric responses of gold nanoparticles

In this work, we demonstrated the fabrication of molecular prime number checkers based on the concentration- and sequence-dependent colorimetric responses of citrate-capped gold nanoparticles (Au NPs) to two simple model chemicals, i.e. cysteine (Cys) and Hg²⁺ ions.

Molecules for security measures: from keypad locks to advanced communication protocols

The idea of using molecules in the context of information security has sparked the interest of researchers from many scientific disciplines. This is clearly manifested in the diversity of the molecular platforms and the analytical techniques used for this purpose, some of which we highlight in this Tutorial Review. Moreover, those molecular systems can be used to emulate a broad spectrum of security measures. For a long time, molecular keypad locks enjoyed a clear preference and the review starts off with a description of how these devices developed. In the last few years, however, the field has evolved into something larger. Examples include more complex authentication protocols (multi-factor authentication and one-time passwords), the recognition of erroneous procedures in data transmission (parity devices), as well as steganographic and cryptographic protection.

A resettable and reprogrammable biomolecular keypad lock with dual outputs based on glucose oxidase-Au nanoclusters-Prussian blue nanocomposite films on an electrode surface

In this work, electrochromic Prussian blue (PB) films were electrodeposited on the surface of indium tin oxide (ITO) electrodes, and a dispersion mixture of glucose oxidase (GOD), chitosan (CS) and gold nanoclusters (AuNCs) was then cast on the PB surface to form CS-AuNC-GOD/PB nanocomposite film electrodes. The blue PB component in the films could be changed into its colourless reduced form of Prussian white (PW) upon application of -0.2 V. The addition of glucose to the solution would produce H₂O₂ with the help of GOD in the films and oxygen in the solution, which could oxidize PW back to PB. In the meantime, the fluorescence emission signal of the AuNCs in the films was greatly influenced by the form of PB/PW. Based on these properties, the amperometric current, fluorescence intensity and UV-vis absorbance of the film electrodes demonstrated potential- and glucose-sensitive ON-OFF behaviors. Thus, a 2-input/3-output biomolecular logic gate system with 3 different types of output signals and a 2-to-1 encoder were developed. Furthermore, a resettable and reprogrammable 3-input biomolecular keypad lock was established with fluorescence intensity and UV-vis absorbance as dual outputs, which greatly enhanced the security level of the keypad lock. This work reported for the first time an enzyme-based keypad lock with dual outputs, which might open a new avenue to design more complicated biomolecular keypad lock systems.

Sequential logic operations with a molecular keypad lock with four inputs and dual fluorescence outputs

A novel coumarin-rhodamine conjugate was prepared, and its metal binding properties were studied by UV/Vis and fluorescence spectroscopy. The conjugate serves as a ratiometric and highly selective fluorescent sensor for Hg(2+) ions. Its metal-responsive spectral properties were utilized to construct a molecular keypad lock with four inputs and dual fluorescence outputs. The complexity of this molecular logic network can greatly enhance the security level of this device.

A resettable and reprogrammable DNA-based security system to identify multiple users with hierarchy

Molecular-level security devices have raised ever-increasing interest in recent years to protect data and information from illegal invasion. Prior molecular keypad locks have an output signal dependent upon not only the appropriate combination but also the exact sequence of inputs, but it cannot be reset or reprogrammed. Here, a DNA-based security system with reset and never-reported reprogram function is successfully developed in proof-of-principle, with which one can change the password in case that the system is cracked. The previous password becomes invalid in the reprogrammed security system. Interestingly, more than one password is designed to permit multiple users to access. By harnessing the intrinsic merit of the different passwords, the system can distinguish different user who is endowed with prior authority. The intelligent device is addressed on solid support and facilitates electronic processes, avoiding chemical accumulation in the system by simple removal of the electrode from the input solution and indicating a main avenue for its further development.

A multiaddressable photochromic bisthienylethene with sequence-dependent responses: construction of an INHIBIT logic gate and a keypad lock

A photochromic bisthienylethene derivative (BIT) containing two imidazole units has been synthesized and fully characterized. When triggered by chemical ions (Ag(+)), protons, and light, BIT can behave as an absorbance switch, leading to a multiaddressable system. BIT exhibits sequence-dependent responses via efficient interaction of the specific imidazole unit with protons and Ag(+). Furthermore, an INHIBIT logic gate and a keypad lock with three inputs are constructed with the unimolecular platform by employing an absorption mode at different wavelengths as outputs on the basis of an appropriate combination of chemical and photonic stimuli.

A visible multi-digit DNA keypad lock based on split G-quadruplex DNAzyme and silver microspheres

A novel visible multi-digit DNA keypad lock system was fabricated based on split G-quadruplex DNAzyme and silver microspheres. The final result of the keypad lock can be easily recognized by the naked eye and the number of inputs for the keypad lock can be flexibly adjusted. This molecular platform showed excellent scalability and flexibility.

Fluorescent probe mimicking multiple logic gates and a molecular keypad lock upon interaction with Hg2+ and bovine serum albumin

The output fluorescence exhibited by an intramolecular charge transfer fluorescent probe 1 providing different chemical inputs mimicked multiple logic gates. A molecular keypad lock security device authorizing password entries (logic memory) and capable of solving crossword puzzles has been constructed by computing the output emission of 1 upon chemical inputs of BSA and Hg(2+). Based on logic operations the devised fluorescent keypad lock could be unlocked upon entering a correct sequence of password, 'BHU'.

An aptamer-based keypad lock system

An aptamer-based security system mimicking keypad lock function was successfully designed. The system was turned "ON" with a strong fluorescent output signal only when the inputs were added according to the correct combination and exact sequence. Otherwise, the system was kept "OFF" to prevent illegal access.