Kaisong Yuan

Real-time pH measurement and regulation of microliter-scale liquid samples are critical for microfluidic biochemical applications. However, traditional magnetic stirring for macroscopic systems is not applicable under such microscale conditions. This work develops an ultrasound-assisted screen-printed electrode (SPE) pH sensor integrated with a 3D-printed ultrasonic reflection cell and piezoelectric excitation unit. Ultrasound-induced acoustic streaming accelerates mass transfer inside microliter-scale samples. Upon acid addition, the ultrasonic-assisted system reaches potentiometric equilibrium far more rapidly than the static non-ultrasonic control. Optimized parameters are 30 s ultrasonic duration and 5 Vpp input amplitude. The sensor shows linearity from pH 3.04 to 4.15 with R² = 0.9919. Phenolphthalein visualization directly confirms ultrasound-enhanced molecular diffusion. Its mass transfer efficiency matches traditional magnetic stirring, and stable fast equilibrium is realized in complex cell culture medium. This acoustofluidic micromixing strategy offers a simple integrated route for pH monitoring and the regulation of micro-volume biological samples.

The presence of hexavalent chromium (Cr ⁶⁺ ) and silver ions (Ag ⁺ ) in pharmaceutical systems poses significant safety concerns due to their toxicity and bioaccumulation potential.

Herein, we report a novel erlotinib (EH) ‐loaded calcium carbonate (CaCO ₃ ) tubular micromotor fabricated via an internal‐filling strategy, achieving a high drug payload of 2.53 × 10 ^{− 1 2} mol per micromotor, which integrates three core functionalities in one system: targeted delivery of EH, pH‐responsive release, and ultrasound‐based tracking. The microtube structures (10 µm in diameter) are prepared by electrochemical deposition, followed by filling the EH@CaCO ₃ microparticle into the interior of the tubular motor. Distinct from the surface coating approach for drug immobilization, this internal‐filling strategy enables substantially greater payloads. The EH@CaCO ₃ tubular micromotor shows favorable bubble and magnetic propulsion capabilities. Serving as a proof‐of‐concept for targeted anti‐cancer drug delivery, these micromotors can transport drugs within microchips channel to the targeted position. Under acidic conditions, CaCO ₃ undergoes decomposition to release the encapsulated drug. Concurrently, the Zn‐based inner structure of the tubular micromotor reacts with hydrogen ions (H ⁺ ), leading to micromotor degradation and thereby facilitating rapid drug release. The as‐released drug shows cell killing ability toward non‐small cell lung cancer cells A549. Meanwhile, as the micromotors move in an acidic environment, the in situ generated bubbles can act as “ultrasonic contrast agents”, thereby enabling real‐time tracking of the micromotors. For potential in vivo applications, this facilitates the tracking of such motors in scenarios where optical microscopy is ineffective. The blood compatibility, coagulation function, and preliminary in vivo immune response evaluation all indicate that the system had good biosafety. This study provides a new idea for the development of a next‐generation micro drug delivery platform with high drug loading, intelligent delivery, and real‐time visualization.

MicroRNAs (miRNAs) are short noncoding RNAs that serve as key biomarkers in various diseases. Traditional detection methods face challenges due to their complexity and enzyme dependency. The one-step electrochemical hairpin probe strategy, while simple and enzyme-free, has limitations in miRNA detection as miRNA signal changes are not prominent. This is mainly because the small molecular size of miRNAs results in weak conformational changes, and the high catalytic activity of nanoenzymes enhances background signals, reducing the signal difference. To address this issue, we developed a new strategy based on controlled nanozyme-substrate accessibility. The introduction of a ferrocene (Fc)/Au/DNA composite as a signal-shielding layer blocked the access of H₂O₂ to the nanozyme graphene oxide/high-entropy alloys (GO/HEAs), which in turn suppressed the·OH generation pathway and markedly enhanced signal suppression after miRNA binding. This method enables highly sensitive and specific discrimination of miRNAs at different concentrations within a one-step detection system. When detecting miR-125b, the sensor achieved a detection limit of 1.67 fM, providing a new concept for the development of highly sensitive and specific biosensing methods.

Herein, we developed a three-dimensional (3D)-printing fluorescence detector that could be connected to the HPLC system, and distinguished by its ease of assembly, cost-effectiveness, and high adaptability. The detector comprises a laser diode, a 3D-printing flow cell, quartz glass, a long-pass filter, a silicon phototube, and a voltmeter. Technically, the flow cell we designed here has a very compact structure, and it is convenient to embed the optical filter and the phototube, which is also a highlight of our detector to ensure the miniaturization of the whole device. Through the optimization of the detector's structural configuration, the adjustment of the various dimensions and relative positions of the detection window, and the removal of the metal encapsulation cover of the silicon phototransistor, we achieved the optimal detection sensitivity and stability. Experimental findings indicate that the 3D-printing fluorescence detector achieves a limit of detection (LOD) of 5 μg mL⁻¹, a linear detection range of 5–60 μg mL⁻¹, and exhibits reasonable inter-day and intra-day stability. Finally, the detector demonstrated its practical utility by successfully separating and detecting a mixed solution of rhodamine 6G and rhodamine B, underscoring its potential for real-world applications.

As a kind of mechanical wave, ultrasound has been widely employed in the biomedical field due to its superiors of deep tissue penetration, non-destructiveness and non-toxicity. In this review, we highlight current progress and prospects in using ultrasound as a powerful tool for disease treatment and medical imaging, including (1) ultrasound as energy input for driving nano/micromotor in drug delivery, this part first introduces the synthesis and motion behavior of nano/micromotors, then reviews the small molecular and macromolecular compounds that the nano/micromotors are delivering; (2) sonosensitive nanomaterials for disease therapy, the sonodynamic, sonopiezoelectric, sonothermal, and sonomechanical therapy will all be covered; (3) ultrasound as a non-invasive technique for nano/micromotor tracking or medical imaging; (4) the sonoporation of nano/microbubble. Future challenges in using ultrasound for disease treatment or medical imaging will also be described in the conclusion part. Graphical abstract

A polarimeter is a common but critical instrument for measuring the optical rotation of chiral compounds, ranging from the pharmaceutical to chemical industry, or even employed in monitoring chemical reactions for research purposes. Developing a portable polarimeter helps to transfer the measurements from the laboratory to on-site detection. Herein, we design a new portable polarimeter with a “hand-held” scale. Technically, we innovatively adopted a rotary potentiometer coupled with a high-precision voltmeter to signify the angle changes after polarized light travels through the chiral compound solution. Compared with the commercial disc polarimeter that uses a dial to measure the optical rotation, such a design shows superiority in being easy to read. This “hand-held” polarimeter meets the high demand for on-site detection on the premise of low cost. Bland-Altman analysis results showed consistency between our device’s optical rotation detection method and the commercial disc polarimeter. The “hand-held” polarimeter can measure the optical rotation of a chiral drug and be applicable to monitor the progress of a chemical reaction. As such, this “hand-held” polarimeter shows great potential to assist scientists in scientific research, or for on-site measurement with high portability. Graphical Abstract