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As sarcosine (SA) is a significant biomarker for the early development of prostate cancer (PCa), its sensitive detection in urine can serve as an effective non-invasive early warning method. Herein, we developed a novel hollow double shell NiMn PBA (NiMn-PBA-DSNB) with outstanding peroxidase-like activity through a facile cation exchange reaction according to the distinct solubility product constants (K_sp) of different Prussian blue analogues (PBAs). Moreover, we innovatively proposed an “enzyme–nanozyme” cascade strategy to realize ultrasensitive SA sensing. This system utilized the enzymatic reaction between SA and sarcosine oxidase (SOX) to generate H₂O₂in situ. In the presence of the generated H₂O₂, the NiMn-PBA-DSNB nanozyme can efficiently catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) to produce blue oxTMB. Consequently, the concentration of SA directly correlated with the absorbance value of oxTMB, providing quantitative detection. Based on this dual-enzyme cascade mechanism, a highly sensitive colorimetric assay was developed for the precise analysis of SA. The assay achieved a wide linear range from 8 to 500 μM, with a low detection limit of 1.75 μM, fully fulfilling the requirements for SA sensing in the urine of PCa patients. The method was also successfully applied to the analysis of real human urine samples, achieving recoveries ranging from 102.15% to 104.35% with relative standard deviations of ≤5.03%, which demonstrates its strong potential for clinical application.

In biological systems, uracil repair in DNA is initiated by uracil-DNA glycosylase (UDG), which removes uracil bases from their corresponding sites to produce abasic sites (AP sites). This enzyme is conserved and functionally critical across living organisms, and its abnormal expression has been proven to be associated with some diseases. Both AP sites and uracil-containing sites (dU sites) impede the replication activity of Pfu DNA polymerase (Pfu-Pol), albeit through distinct mechanisms. AP sites, caused by base loss, generally slow down replication, while dU sites induce stalling by being recognized by the uracil-binding pocket of the enzymes. Our key finding demonstrates that the ability of Pfu-Pol to bypass AP sites is significantly greater than its capacity to traverse dU sites within an appropriate template concentration range, resulting in higher efficiency in generating full-length products. Exploiting this kinetic difference, we developed a simple and sensitive method for quantifying UDG activity. UDG converts dU-containing templates into AP-containing templates. This conversion accelerates Pfu-Pol-mediated amplification, which is quantitatively measured in a Quantitative Real-time PCR (qPCR) assay as a decrease in the cycle threshold (Ct) value. Under optimized conditions, the quantification of UDG was enabled within a range of 0.0001 to 0.01 U mL⁻¹ with high selectivity. UDG was successfully detected in Hela cell samples at protein inputs corresponding to 10 cells.

The potential use of miniature ion trap mass spectrometry (mini-IT-MS) as a reliable on-site screening tool remains largely unrealized, primarily due to the lack of compatible spectral libraries and a limited understanding of the unique ion chemistry inherent to the platform. During the analysis of quinolone antibiotics, we identified the formation of intense, solvent-dependent adduct ions during collision-induced dissociation (CID). These ions are not presented in conventional spectral databases and pose a considerable risk of misidentification. This study systematically demonstrates that this phenomenon originates from an intra-trap, gas-phase SN2 esterification reaction between the carboxyl group of quinolones and alcohol molecules present in the mobile phase. The proposed mechanism was conclusively validated through solvent-exchange experiments, CID energy-dependent analyses, and isotopic labeling. Notably, the MS³ spectrum of the adduct ion closely matched the MS² spectrum of the original precursor ion, confirming the ester structure of the adduct. Building on this mechanistic understanding, we constructed a customized tandem mass spectral library that explicitly incorporates these adduct ions as diagnostic features. This strategy enabled the unambiguous identification of all 14 quinolones in a standard mixture and demonstrated high reliability in screening spiked fish and shrimp samples, effectively transforming an analytical interferent into a robust identification tool. This work establishes a paradigm for tackling platform-specific analytical challenges through fundamental ion chemistry research, laying the groundwork for more reliable on-site analysis using miniature mass spectrometers.

In the field of materials science, using diverse experimental and computational methods is a well-known approach as the most effective route to comprehensive material characterization. Combining high-resolution transmission electron microscopy (TEM) techniques and X-ray diffraction (XRD) data analysis enables simultaneous integration of multifaceted data, improving research productivity, accuracy and application development. The pathway from qualitative to quantitative results requires advanced data analysis approaches with a capability of extracting meaningful physical parameters from all complex datasets. While there is no universal method presently existing to derive physical properties directly from the chemical composition and TEM images alone, traditional theoretical approaches and modern machine learning (ML) methods, particularly zero-code artificial intelligence AI/ML platforms, seem to be promising in this area. The actual review deals with current cases of TEM data analysis, particularly where combining TEM and diffraction methods enables enhanced nanoparticle characterization, emphasizing parameters like particle size, coherent domain size, agglomeration, and complicated fractal-like shape, all of which could be rather crucial for basic materials science and further industrial applications.

A three-dimensional (3D) composite material, which mimics Allium macrostemon bunge-like manganese (Mn) tetroxide (amb-Mn₃O₄), was prepared utilizing a simple one-pot hydrothermal method. The microstructure of Mn₃O₄ was adjusted by the addition of polyethylene glycol 400 (PEG 400). Experimental results showed that the best amb-Mn₃O₄ material for dopamine (DA) detection could be achieved when the volume ratio of PEG 400 to purified water was 1 : 3. The electrochemical sensor developed with this material revealed a good linear relationship with DA concentrations in 2 concentration ranges: 0.0001–0.0156 mmol L⁻¹ and 0.0196–0.4196 mmol L⁻¹ measured by chronoamperometry (CA). The sensor possessed a limit of detection (LOD) of 0.028 μmol L⁻¹ and a sensitivity of 5281.6 µA (mmol L⁻¹)⁻¹ cm⁻² towards DA. Furthermore, the sensor was efficient in detecting DA levels from human biological samples such as urine and serum, which is an optimal strategy for the advancement of highly efficient “electrochemical sensors” for DA analysis.

As a broad-spectrum anticancer agent, doxorubicin (DOX) is extensively applied in the treatment of diverse human tumors. In this work, green-emitting fluorescent silicon doped carbon dots (Si-CDs) were fabricated through a straightforward solvent-thermal method. The as-prepared Si-CDs were quenched through the inner filter effect (IFE) with the addition of DOX. A fluorescence method based on Si-CDs was established for the quantitative analysis of DOX. The proposed approach showed a linear relationship between fluorescence intensity and DOX concentrations spanning from 0.05 to 50 µM, and its limit of detection reached as low as 6 nM. Meanwhile, the presented assay shows remarkable ability to detect DOX in practical samples with satisfactory recoveries, which may have important implications for the clinical monitoring of DOX therapy.

Capillary electrophoresis-sodium dodecyl sulfate (CE-SDS), a high-resolution and high-sensitivity analytical technique, is an essential tool for analyzing the critical quality attributes (CQAs) of monoclonal antibodies (mAbs) and their derivatives, including antibody–drug conjugates (ADCs) and bispecific antibodies (bsAbs). This study systematically reviews the applications of CE-SDS in analyzing the purity and fragments of mAbs, characterizing positional isomers of ADCs, and identifying mismatch impurities in bsAbs. Focusing on the core technical challenge that CE-SDS cannot be directly coupled with mass spectrometry (MS) for fragment structure identification, the study summarizes technical solutions based on indirect identification approaches and offline/online coupling strategies with Capillary Zone Electrophoresis-Mass Spectrometry (CZE-MS). In addition, from a regulatory science perspective, this study details the key considerations for method validation, establishment of quality standards, and preparation of regulatory submissions for CE-SDS. This study aims to provide a systematic reference for the development and quality control of related biopharmaceuticals, highlighting future development directions, including high-throughput analysis, coupling techniques, and degradation prediction.