The subject invention provides materials and methods for single-step fluorescence and electrochemical detection of small molecules, e.g., fentanyl and its analogs, in a sample. The subjection invention provides nucleic acids materials, e.g., aptamers (nucleic acid oligonucleotides) that can bind to fentanyl and its analogs with nanomolar affinity and high specificity against illicit drugs, adulterants, and cutting agents commonly existing in seized samples. The method for detecting fentanyl and/or its analogs in a sample comprises contacting the sample with an aptamer-based sensor selective for fentanyl and its analogs, and sensitively, specifically, and rapidly detecting fentanyl and/or its analogs in the sample.

One aspect according to the present disclosure relates to a novel nucleic acid ligand which is a new class of nucleic acid compound, the existence of which was considered impossible in the prior art. The novel nucleic acid ligand has specific binding affinity with respect to at least two different targets having three-dimensional structures, and the binding sites for the at least two targets are formed in or from a single nucleic acid ligand. The novel nucleic acid ligand according the present disclosure can simultaneously solve several problems of existing aptamers that the prior art could not solve. One aspect according to the present disclosure relates to a novel screening method for identifying the above-mentioned novel nucleic acid ligand. The novel screening method uses a step for sequentially contacting at least two different targets having three-dimensional structures to screen a novel nucleic acid ligand that was previously thought impossible.

Molecular beacons and developmental methods related thereto. Methods include obtaining a nucleotide sequence for an aptamer that binds to a target analyte. The aptamer comprises a binding domain nucleotide sequence, a first domain nucleotide sequence, and a displacement domain nucleotide sequence complementary to the first domain nucleotide sequence. A molecular beacon is developed based on the nucleotide sequence of the aptamer by preserving the binding domain nucleotide sequence and truncating or extending one or both of the first domain nucleotide sequence or the displacement domain nucleotide sequence. The resultant molecular beacon is developed such that the molecular beacon comprises a Gibbs free energy value that is greater than the Gibbs free energy value of the aptamer.

The invention provides xeno-nucleic acid particle display libraries, methods for identifying functional non-natural nucleic acid (XNA) aptamers using the particle display libraries, and compositions comprising XNA aptamers identified by screening candidate molecules using the xeno-nucleic acid particle display libraries.

Provided herein are devices, methods and compositions useful in obtaining aptamers for biosensor probes. Such methods, devices and compositions are useful for novel clinical or companion drug diagnostic and personalized theranostic assays.

The invention relates to the technical field of bioengineering and provides a method for improving the specificity and affinity of an aptamer. The method includes: S1, screening a target of an aptamer from a compound information database by virtual computing; S2, verifying the screening result in Step S1 through experiments; S3, performing virtual saturation mutation on a site of the aptamer, and screening out a mutation site of the aptamer; S4, performing base substitution to the mutation site of the aptamer; and S5, detecting the binding parameter of the aptamer after base substitution with the target screened in Step S1, and selecting an aptamer with improved specificity and affinity after base substitution. An efficient molecular design-guided method is developed by computer rational calculation, to improve the specificity and binding affinity of the aptamer by directional modification. The present invention is of great significance for the practical application of aptamers.

This invention consists of a method for the development of personalized target anticancer therapies based on aptamers and through the systemic modeling of an individual in microfluidic devices. This invention is embodied in microfluidic devices, connections, systems, and methods for the development specific aptamers for the relevant complex biological environment targets. In a first mode, the invention provides methods for the development of target therapies which involves the maintenance of target cancerous cells in co-culture with non-target and non-cancerous cells by using microfluidic devices modularly arranged in closed systems for the development of aptamers. In a second mode, the invention provides a method for the development of target therapies, which includes the maintenance of target cells in co-culture with non-target cells by using microfluidic devices modularly arranged in closed systems. In this case, the invention provides the development of aptamers for the relevant target in homeostatic balance with the components of the fluid conditioned by the co-culture with non-target cells.

Monocyte-specific nucleic acid aptamers and lipid nanoparticles comprising such for use in drug delivery. Also disclosed herein are use of the aptamer-based lipid nanoparticle drug delivery system for treating heart injury.

The invention provides xeno-nucleic acid particle display libraries, methods for identifying functional non-natural nucleic acid (XNA) aptamers using the particle display libraries, and compositions comprising XNA aptamers identified by screening candidate molecules using the xeno-nucleic acid particle display libraries.

Provided herein are aptamers that target cytotoxic T-lymphocyte and methods of use thereof.