Provided herein, in some embodiments, are systems, methods, compositions, and kits for detecting and quantifying analytes using a primary analyte binding molecule conjugated to a nucleic acid template.

In various embodiments a molecular circuit is disclosed. The circuit comprises a negative electrode, a positive electrode spaced apart from the negative electrode, and an enzyme molecule conductively attached to both the positive and negative electrodes to form a circuit having a conduction pathway through the enzyme. In various examples, the enzyme is a polymerase. The circuit may further comprise molecular arms used to wire the enzyme to the electrodes. In various embodiments, the circuit functions as a sensor, wherein electrical signals, such as changes to voltage, current, impedance, conductance, or resistance in the circuit, are measured as substrates interact with the enzyme.

Described herein is an amperometric biosensor, e.g., chronoamperometric biosensor for the measurement of the concentration of nicotine. Also disclosed herein is a wearable nicotine biosensor device and a biosensor that detects nicotine in smoke. The biosensor disclosed herein comprises a nicotine-catalyzing enzyme, such as NicA2 or mutant NicA2 enzymes. Also described herein are systems comprising said amperometric biosensor, e.g., chronoamperometric biosensor and methods of using said chronoamperometric biosensor.

In an example, a flow cell includes a substrate, a selectively removable porous molecular network on the substrate and defining exposed substrate regions, and sequencing surface chemistry on at least some of the exposed regions. The sequencing surface chemistry is selected from the group consisting of i) an activated pad, a polymer layer attached to the activated pad, and a primer attached to the polymer layer; or ii) a nanostructure and an enzyme attached to the nanostructure.

Devices and methods are described for providing continuous measurement of an analyte concentration. In some embodiments, the device has a sensing mechanism and a sensing membrane that includes at least one surface-active group-containing polymer and that is located over the sensing mechanism. The sensing membrane may have a bioprotective layer configured to substantially block the effect and/or influence of non-constant noise-causing species.

Devices and methods are described for providing continuous measurement of an analyte concentration. In some embodiments, the device has a sensing mechanism and a sensing membrane that includes at least one surface-active group-containing polymer and that is located over the sensing mechanism. The sensing membrane may have a bioprotective layer configured to substantially block the effect and/or influence of non-constant noise-causing species.

A slot die shim for use with a slot die, the slot die shim including a first channel configured to receive a first coating, a second channel configured to receive a second coating, and a third channel configured to receive a third coating. The slot die shim simultaneously dispenses the first coating through the first channel, the second coating through the second channel, and the third coating through the third channel onto a substrate. The coatings can be applied at different flow rates and include different test reagents. A vacuum force is applied to the first, second, and third coatings to control a width and a thickness of each of the coatings and a gap or distance between the coatings. The first, second, and third coatings are placed near one another or directly in contact with one another to minimize the area required for the coatings.

Provided is a method for screening a modulator of a viral infection by detecting an interaction of angiotensin converting enzyme 2 (ACE2) and a spike protein with a biosensing platform. Also provided is a compound of formula (I) as a modulator of a viral infection, where R, X, A, R.sub.3 to R.sub.5, and m are as defined herein, and a method for protecting a subject from a viral infection by administering with the compound.

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Disclosed herein are compositions for permeable outer diffusion control membranes for creatinine and creatine sensors and methods of making such membranes.

Disclosed herein is an ultralow concentration sensor of biomarkers, and the use thereof to help heath industry, medical centers and food industry to sense biomarkers by catalyst assisted charge transfer from the biomarkers to the sensor device, resulting increased electrical resistance of the sensor. Specifically, perovskite nickelate RNiO.sub.3 is used to sense biological material facilitated by specific enzymatic activity in the proximity.