The adsorption of dopamine on gold and its interactions with iron(III) ions studied by microcantilevers

Microcantilever array instrument based on optical fiber and performance analysis

We developed a microcantilever array biosensor instrument based on optical readout from a microcantilever array in fluid environment. The microcantilever signals were read out sequentially by laser beams emitted from eight optical fibers. The optical fibers were coupled to lasers, while the other ends of the fibers were embedded in eight V-grooves with 250 μm pitch microfabricated from a Si wafer. Aspherical lens was used to keep the distance between lasers. A programmable logic controller was used to make the system work stably. To make sure that the output of lasers was stable, a temperature controller was set up for each laser. When the deflection signal was collected, lasers used here were set to be on for at least 400 ms in each scanning cycle to get high signal-to-noise ratio deflection curves. A test was performed by changing the temperature of the liquid cell holding a microcantilever array to verify the consistent response of the instrument to the cantilever deflections. The stability and conformance of the instrument were demonstrated by quantitative detection of mercury ions in aqueous solution and comparison detection of clenbuterol by setting test and reference cantilevers. This microcantilever array detection instrument can be applied to highly sensitive detection of chemical and biological molecules in fluid environment.

Morphology-tunable polydopamine nanoparticles and their application in Fe3+ detection

In this work, we discovered the morphology transformation property of polydopamine (PDA) nanomaterials, the addition of Fe³⁺ initiated the dramatic morphology transformation of PDA dots from aggregated plate-like to uniform willow-leaf-like morphology. Further study revealed that this fascinating morphology transformation process could be attributed to the oxidative nature and coordination characteristic of Fe³⁺. This is the first report on the morphology transformation ability of PDA, and a probable self-assembled mechanism was proposed to explain this issue. Besides, we noticed that morphological and fluorescent properties of PDA dots were closely related, thus a fluorescent Fe³⁺ detection method was presented based on the morphology-tunable PDA dots. With the proposed method, selective Fe³⁺ detection was achieved with a wide linear dynamic range of 10μM to 1mM. Furthermore, since the morphology tuning behavior of PDA dots was easy to operate, we anticipate this ability will find significant utility in sensing, drug delivery, and tissue engineering.

Microcantilever biosensors for chemicals and bioorganisms

In the last fifteen years, microcantilevers (MCLs) have been emerging as a sensitive tool for the detection of chemicals and bioorganisms. Because of their small size, lightweight, and high surface-to-volume ratio, MCL-based sensors improve our capability to detect and identify biological agents by orders of magnitude. A biosensor is a device for the detection of an analyte that combines a biological component with a physicochemical detector component. The MCL biosensors have recently been reviewed in several papers. All of these papers were organized based on the sensing biological elements (antibody, enzyme, proteins, etc.) for recognition of analytes. In this review, we intend to summarize the microcantilever biosensors in a format of each specific chemical and bioorganism species to make information on individual biosensors easily accessible. We did this to aid researchers to locate relevant references.