Improve Detection Sensitivity Research Articles

Applications of metals and metal compounds in improving the sensitivity of microfluidic biosensors - a review.

The enhancement of detection sensitivity in microfluidic sensors has been a continuously explored field. Initially, many strategies for sensitivity improvement involved introducing enzyme cascade reactions, but enzyme-based reactions posed challenges in terms of cost, stability, and storage. Therefore, there is an urgent need to explore enzyme-free cascade amplification methods, which are crucial for expanding the application range and improving detection stability. Metal or metal compound nanomaterials have gained great attention in the exploitation of microfluidic sensors due to their ease of preparation, storage, and lower cost. The unique physical properties of metallic nanomaterials, including surface plasmon resonance, surface-enhanced Raman scattering, metal-enhanced fluorescence, and surface-enhanced infrared absorption, contribute significantly to enhancing detection capabilities. The metal-based catalytic nanomaterials, exemplified by Fe3O4 nanoparticles and metal-organic frameworks, are considered viable alternatives to biological enzymes due to their excellent performance. Herein, we provide a detailed overview of the applications of metals and metal compounds in improving the sensitivity of microfluidic biosensors. This review not only highlights the current developments but also critically analyzes the challenges encountered in this field. Furthermore, it outlines potential directions for future research, contributing to the ongoing development of microfluidic biosensors with improved detection sensitivity.

Synergistic Enhancement Effect of Ag/rGO as SERS Platform for Capture and Trace Detection of Fenvalerate Molecules

Surface-enhanced Raman scattering (SERS) provides an alternative rapid detection method for pesticide residues in food, but fenvalerate possesses poor affinity to the novel metal substrate, thus restricting its analysis. To break this bottleneck, a SERS-active platform with an Ag/rGO composite structure was engineered using a facile method for fenvalerate detection. Ag nanoparticles with a 60 nm diameter can grow evenly on the top and bottom of rGO layers under intense ultrasonic oscillation, and rGO in hybrid material acts as an ideal hotspot holder between the gaps of Ag nanoparticles, not only allowing the interaction area to be enhanced both electromagnetically and chemically but also enabling the capture and enrichment of fenvalerate pesticide molecules into the “hotspot” area to improve detection sensitivity. Ag/rGO composite substrate possesses superior SERS performance with an ultralow detectable concentration of 4-aminothiophenol (10−10 M) and good reproducibility, endowing the material with a better enhancement effect than pure Ag nanoparticles. When used as the SERS substrate for fenvalerate detection, Ag/rGO composite material showed excellent performance in both experiments and theoretical calculation, with the limit of detection (LOD) of fenvalerate being as low as 1.69 × 10−5 mg/kg and a detection model with an R2 of 99.2%, demonstrating its exciting potential as a SERS substrate for pesticides detection.

Detection of fucosylated extracellular vesicles miR-4732-5p related to diagnosis of early lung adenocarcinoma by the electrochemical biosensor

Our preliminary investigation has identified the potential of serum fucosylated extracellular vesicles (EVs) miR-4732-5p in the early diagnosis of lung adenocarcinoma (LUAD) by a fucose-captured strategy utilizing lentil lectin (LCA)-magnetic beads and subsequent screening of high throughput sequencing and validation of real-time quantitative polymerase chain reaction (RT-qPCR). Considering the relatively complicated procedure, expensive equipment, and stringent laboratory condition, we have constructed an electrochemical biosensor assay for the detection of miR-4732-5p. miR-4732-5p is extremely low in serum, down to the fM level, so it needs to be detected by highly sensitive electrochemical methods based on the Mg2+-dependent DNAzyme splitting nucleic acid lock (NAL) cycle and hybridization chain reaction (HCR) signal amplification. In this study, signal amplification is achieved through the dual amplification reactions using NAL cycle in combination with HCR. In addition, hybridized DNA strands bind to a large number of methylene blue (MB) molecules to enhance signaling. Based on the above strategy, we further enhance our signal amplification strategies to improve detection sensitivity and accuracy. The implementation of this assay proceeded as follows: initially, miR-4732-5p was combined with NAL, and then Mg2+-dependent DNAzyme splitted NAL to release auxiliary DNA (S1) strands, which were subsequently captured by the immobilized capture probe DNA (C1) strands on the electrode surface. Following this, abundant quantities of DNA1 (H1) and DNA2 (H2) tandems were generated by HCR, and S1 strands then hybridized with the H1 and H2 tandems through base complementary pairing. Finally, MB was bonded to the H1 and H2 tandems through π–π stacking interaction, leading to the generation of a signal current upon the detection of a potential capable of inducing a redox change of MB by the electrode. Furthermore, we evaluated the performance of our developed electrochemical biosensor assay. The results demonstrated that our assay is a reliable approach, characterized by its high sensitivity (with a detection limit of 2.6 × 10−17 M), excellent specificity, good accuracy, reproducibility, and stability. Additionally, it is cost-effective, requires simple operation, and is portable, making it suitable for the detection of serum fucosylated extracellular vesicles miR-4732-5p. Ultimately, this development has the potential to enhance the diagnostic efficiency for patients with early-stage LUAD.

Reducing Cathodic Drift during Isoelectric Focusing Using Microscale Immobilized pH Gradient Gels.

Microfluidic analytical tools play an important role in miniaturizing targeted proteomic assays for improved detection sensitivity, throughput, and automation. Microfluidic isoelectric focusing (IEF) can resolve proteoforms in lysate from low-to-single cell numbers. However, IEF assays often use carrier ampholytes (CAs) to establish a pH gradient for protein separation, presenting limitations like pH instability in the form of cathodic drift (migration of focused proteins toward the cathode). Immobilized pH gradient (IPG) gels reduce cathodic drift by covalently immobilizing the pH buffering components to a matrix. To our knowledge, efforts to implement IPG gels at the microscale have been limited to glass microdevices. To adapt IEF using IPGs to widely used microfluidic device materials, we introduce a polydimethylsiloxane (PDMS)-based microfluidic device and compare the microscale pH gradient stability of IEF established with IPGs, CAs, and a hybrid formulation of IPG gels and CAs (mixed-bed IEF). The PDMS-based IPG microfluidic device (μIPG) resolved analytes differing by 0.1 isoelectric point within a 3.5 mm separation lane over a 20 min focusing duration. During the 20 min duration, we observed markedly different cathodic drift velocities among the three formulations: 60.1 μm/min in CA-IEF, 2.5 μm/min in IPG-IEF (∼24-fold reduction versus CA-IEF), and 1.4 μm/min in mixed-bed IEF (∼43-fold reduction versus CA-IEF). Lastly, mixed-bed IEF in a PDMS device resolved green fluorescent protein (GFP) proteoforms from GFP-expressing human breast cancer cell lysate, thus establishing stability in lysate from complex biospecimens. μIPG is a promising and stable technique for studying proteoforms from small volumes.

Spectral fusion-based machine learning classifiers for discriminating membrane breakage in multiple scenarios

Membrane breakage can lead to filtration failure, which allows harmful substances to enter the effluent, posing potential hazards to human health and the environment. This study is an innovative combination of fluorescence and ultraviolet-visible (UV–Vis) spectroscopy to identify membrane breakage. It aims to unravel more comprehensive information, improve detection sensitivity and selectivity, and enable real-time monitoring capabilities. Fluorescence and UV–Vis data are extracted through variance partitioning analysis (VPA) and integrated through a decision tree algorithm to form a superior system with enhanced discrimination capabilities. VPA improves discrimination efficiency by extracting key information from spectral data and eliminating redundancy. The decision tree algorithm, on the other hand, can process large amounts of data simultaneously. In addition, the method has a wide range of applications and can be used in various scenarios accurately. The scenarios include domestic sewage, micropollutant water, aquaculture wastewater, and secondary treated sewage. The experimental results validate the application of machine learning classifiers in membrane breakage detection with an accuracy rate of 96.8 % to 97.4 %.

Tuning quantum dots emission on DNA tetrahedron/silica nanosphere/graphene oxide nanointerface for ratiometric fluorescence assay of Pb2+ in multiplex samples

BackgroundAssembling framework nucleic acid (FNA) nanoarchitectures and tuning luminescent quantum dots (QDs) for fluorescence assays represent a versatile strategy in analytical territory. Rationally, FNA constructs could offer a preferential orientation to efficiently recognize the target and improve detection sensitivity, meanwhile, regulating size-dependent multicolor emissions of QDs in one analytical setting for ratiometric fluorescence assay would greatly simplify operation procedures. Nonetheless, such FNA/QDs-based ratiometric fluorescence nanoprobes remain rarely explored. ResultsWe designed a sensitive and signal amplification-free fluorescence aptasensor for lead ions (Pb2+) that potentially cause extensive contamination to environment, cosmetic, food and pharmaceuticals. Red and green emission CdTe quantum dots (rQDs and gQDs) were facilely prepared. Moreover, silica nanosphere encapsulating rQDs served as quantitative internal reference and scaffold to anchor a predesigned FNA and DNA sandwich containing Pb2+ binding aptamer and gQD modified DNA signal reporter. On binding of Pb2+, the gQD-DNA signal reporter was set free, resulting in fluorescence quenching at graphene oxide (GO) interface. Owing to the rigid structure of FNA, the fluorescence signal reporter orderly arranged at the silica nanosphere could sensitively respond to Pb2+ stimulation. The dose-dependent fluorescence signal-off mode enabled ratiometric analysis of Pb2+ without cumbersome signal amplification. Linear relationship was established between fluorescence intensity ratio (I555/I720) and Pb2+ concentration from 10 nM to 2 μM, with detection limit of 1.7 nM (0.43 ppb), well addressing the need for Pb2+ routine monitoring. The designed nanoprobe was applied to detection of Pb2+ in soil, cosmetic, milk, drug, and serum samples, with the sensitivity comparable to conventional ICP-MS technique. SignificanceGiven the programmable design of FNA and efficient recognition of target, flexible tuning of QDs emission, and signal amplification-free strategy, the present fluorescence nanoprobe could be a technical criterion for other heavy metal ions detection in a straightforward manner.

Construction of an Au/g-C3N4/GO/Au substrate by a layer-by-layer assembly approach for surface-enhanced Raman spectroscopy

In this work, an Au/g-C3N4/GO/Au hybrid nanofilm for surface-enhanced Raman scattering (SERS) substrate application was prepared by a facile layer-by-layer assembly technique using nanosheet-structured graphitic carbon nitride (g-C3N4), graphene oxide (GO) and 40 nm-gold nanoparticles (Au NPs). The effects of composition, assembly sequence and assembly cycles on the SERS performance were optimized to achieve the SERS-active substrate. The detection limit of Au/g-C3N4/GO/Au substrate for crystal violet and rhodamine 6 G probe molecules reached as high as 10−8 M, with good stability and uniformity. Its further application in food colorants detection (erythrosine, carmine and temptation red) had successfully met the national food safety standards and the quantitative detection for erythrosine and temptation red had also been established. Based on finite-difference time-domain element simulation and density functional theory quantum chemical calculation, the mechanism of the SERS effect of the substrate was unveiled, which is attributed to the combination of electromagnetic enhancement effect of Au nanoparticle aggregates and chemical enhancement effect of GO and g-C3N4. Notably, water droplet evaporation induced Raman enhancement was observed on the Au/g-C3N4/GO/Au substrate. This can be ascribed to the inhomogeneous evaporation of the droplet that promotes the enrichment of the probe molecules into the center of the droplet. This novel enhancement strategy provides a new idea for further improving detection sensitivity of SERS substrate materials.

High spatial resolution surface plasmon resonance imaging using a plasmonic chip.

The surface plasmon resonance (SPR) technique has been widely applied to biosensing technologies for the rapid quantification of biomolecules without enzyme and fluorescent labeling. However, the conventional prism-coupling SPR method generally has a detection area of a few mm2, and the large contribution of the background signal forms a barrier to highly sensitive detection. Based on a highly spatially resolved SPR method, the present study constructed a scanning GC-SPR imaging instrument using an objective lens with a high numerical aperture and a plasmonic chip that could be used for grating-coupled SPR. Focusing light on the diffraction limit can suppress background signals and improve detection sensitivity. SPR imaging can also be performed by scanning a focal spot. Using this method, the refractive index of a mixture of water and dimethyl sulfoxide was measured with a detection accuracy of 2.43 × 10-3 RIU. Polydopamine films prepared with a thickness of <5nm were also measured, and each film thickness was evaluated with high sensitivity from the effective refractive index detected in a small area of <1 µm2.

Direct detection of acetylcholinesterase by Fe(HCOO)2.6(OH)0.3. H2O nanosheets with oxidase-like activity on a smartphone platform

Monitoring acetylcholinesterase (AChE) is crucial in clinical diagnosis and drug screening. Traditional methods for detecting AChE usually require the addition of intermediates like acetylthiocholine, which complicates the detection process and introduces interference risks. Herein, we develop a direct colorimetric assay based on alkaline iron formate nanosheets (Fe(HCOO)2.6(OH)0.3·H2O NSs, Fef NSs) for the detection of AChE without any intermediates. The as-prepared Fef NSs exhibit oxidase-like activity, catalyzing the generation of O2·-, 1O2 and ·OH, which leads to a color change from colorless to blue when exposed to 3,3′,5,5′-tetramethylbenzidine. AChE directly inhibits the oxidase-like activity of Fef NSs, resulting in a hindered color reaction, enabling the detection of AChE. The biosensor has a linear detection range of 0.1–30 mU/mL, with a minimum detection limit of 0.0083 mU/mL (S/N = 3), representing a 100-fold improvement in detection sensitivity over the traditional Ellman's method. Satisfactory results were obtained when analyzing real AChE samples. Attractively, a method for the quantitative detection of AChE by a smartphone is established based on the Fef NSs. This method enables instant acquisition of AChE concentrations, achieving real-time visualized detection.

NaI gamma camera performance for high energies: Effects of crystal thickness, photomultiplier tube geometry and light guide thickness.

Gamma camera imaging, including single photon emission computed tomography (SPECT), is crucial for research, diagnostics, and radionuclide therapy. Gamma cameras are predominantly based on arrays of photon multipliers tubes (PMTs) that read out NaI(Tl) scintillation crystals. In this way, standard gamma cameras can localize ɣ-rays with energies typically ranging from 30 to 360keV. In the last decade, there has been an increasing interest towards gamma imaging outside this conventional clinical energy range, for example, for theragnostic applications and preclinical multi-isotope positron emission tomography (PET) and PET-SPECT. However, standard gamma cameras are typically equipped with 9.5mm thick NaI(Tl) crystals which can result in limited sensitivity for these higher energies. Here we investigate to what extent thicker scintillators can improve the photopeak sensitivity for higher energy isotopes while attempting to maintain spatial resolution. Using Monte Carlo simulations, we analyzed multiple PMT-based configurations of gamma detectors with monolithic NaI (Tl) crystals of 20 and 40mm thickness. Optimized light guide thickness together with 2-inch round, 3-inch round, 60×60 mm2 square, and 76×76 mm2 square PMTs were tested. For each setup, we assessed photopeak sensitivity, energy resolution, spatial, and depth-of-interaction (DoI) resolution for conventional (140keV) and high (511keV) energy ɣ using a maximum-likelihood algorithm. These metrics were compared to those of a "standard" 9.5mm-thick crystal detector with 3-inch round PMTs. Estimated photopeak sensitivities for 511keV were 27% and 53% for 20 and 40mm thick scintillators, which is respectively, 2.2 and 4.4 times higher than for 9.5mm thickness. In most cases, energy resolution benefits from using square PMTs instead of round ones, regardless of their size. Lateral and DoI spatial resolution are best for smaller PMTs (2-inch round and 60×60 mm2 square) which outperform the more cost-effective larger PMT setups (3-inch round and 76×76 mm2 square), while PMT layout and shape have negligible (<10%) effect on resolution. Best spatial resolution was obtained with 60×60 mm2 PMTs; for 140keV, lateral resolution was 3.5mm irrespective of scintillator thickness, improving to 2.8 and 2.9mm for 511keV with 20 and 40mm thick crystals, respectively. Using the 3-inch round PMTs, lateral resolutions of 4.5 and 3.9mm for 140keV and of 3.5 and 3.7mm for 511keV were obtained with 20 and 40mm thick crystals respectively, indicating a moderate performance degradation compared to the 3.5 and 2.9mm resolution obtained by the standard detector for 140 and 511keV. Additionally, DoI resolution for 511keV was 7.0 and 5.6mm with 20 and 40mm crystals using 60×60 mm2 square PMTs, while with 3-inch round PMTs 12.1 and 5.9mm were obtained. Depending on PMT size and shape, the use of thicker scintillator crystals can substantially improve detector sensitivity at high gamma energies, while spatial resolution is slightly improved or mildly degraded compared to standard crystals.

An ionic liquid-modified PEDOT/Ti3C2TX based molecularly imprinted electrochemical sensor for pico-molar sensitive detection of L-Tryptophan in milk

L-Tryptophan (L-Trp) is essential for the human body and can only be obtained externally. It is important to develop a method to efficiently detect L-Trp in food. In this work, ionic liquid (IL) modified poly(3,4-ethylendioxythiophene)/ Titanium carbide (PEDOT/Ti3C2TX) was used as a substrate material to improve detection sensitivity. Molecular imprinted polymers (MIP) film for specific recognition of L-Trp was fabricated on the surface of modified electrodes using electrochemical polymerization. The monitoring results showed that the molecularly imprinted electrochemical sensors (MIECS) exhibited good linearity ranges (10−6 - 0.1 μM and 0.1–100 μM) with a low detection limit (LOD) of 2.09 × 10−7 μM. In addition, the MIECS exhibited remarkable stability, reproducibility, and immunity to interference. A good recovery (93.54–99.59%) was demonstrated in the detection of milk. The sensor was expected to be developed as a highly selective and sensitive portable assay, and applied to the detection of L-Trp in food.

Recent advances in high-performance liquid chromatography tandem mass spectrometry techniques for analysis of DNA damage and epigenetic modifications

Environmental exposure would cause DNA damage and epigenetic modification changes, potentially resulting in physiological dysfunction, thereby triggering diseases and even cancer. DNA damage and epigenetic modifications are thus promising biomarkers for environmental exposures and disease states. Benefiting from its high sensitivity and accuracy, high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) is considered the “gold standard technique” for investigating epigenetic DNA modifications. This review summarizes the recent advancements of UHPLC-MS/MS-based technologies for DNA damage and epigenetic modifications analysis, mainly focusing on the innovative methods developed for UHPLC-MS/MS-related pretreatment technologies containing efficient genomic DNA digestion and effective removal of the inorganic salt matrix, and the new strategies for improving detection sensitivity of liquid chromatography-mass spectrometry. Moreover, we also summarized the novel hyphenated techniques of the advanced UHPLC-MS/MS coupled with other separation and analysis methods for the measurement of DNA damage and epigenetic modification changes in special regions and fragments of chromosomes.

Surface Modification of Ultrasonic Cavitation by Surfactants Improves Detection Sensitivity of α-Synuclein Amyloid Seeds.

The rapid amplification and sensitive detection of α-synuclein (αSyn) seeds is an efficient approach for the early diagnosis of Parkinson's disease. Ultrasonication stands out as a promising method for the rapid amplification of αSyn seeds because of its robust fibril fragmentation capability. However, ultrasonication also induces the primary nucleation of αSyn monomers, deteriorating the seed detection sensitivity by generating seed-independent fibrils. In this study, we show that an addition of surfactants to the αSyn monomer solution during αSyn seed detection under ultrasonication remarkably improves the detection sensitivity of the αSyn seeds by a factor of 100-1000. Chemical kinetic analysis reveals that these surfactants reduce the rate of primary nucleation while promoting the fragmentation of the αSyn fibrils under ultrasonication. These effects are attributed to the modification of the ultrasonic cavitation surface by the surfactants. Our study enhances the utility of ultrasonication in clinical assays targeting αSyn seeds as the Parkinson's disease biomarker.

Self-Feedback DNAzyme Motor for Cascade-Amplified Imaging of mRNA in Live Cells and In Vivo.

DNA motors have attracted extensive interest in biosensing and bioimaging. However, the amplification capacity of the existing DNA motor systems is limited since the products from the walking process are unable to feedback into the original DNA motor systems. As a result, the sensitivities of such systems are limited in the contexts of biosensing and bioimaging. In this study, we report a novel self-feedback DNAzyme motor for the sensitive imaging of tumor-related mRNA in live cells and in vivo with cascade signal amplification capacity. Gold nanoparticles (AuNPs) are modified with hairpin-locked DNAzyme walker and track strands formed by hybridizing Cy5-labeled DNA trigger-incorporated substrate strands with assistant strands. Hybridization of the target mRNA with the hairpin strands activates DNAzyme and promotes the autonomous walking of DNAzyme on AuNPs through DNAzyme-catalyzed substrate cleavage, resulting in the release of many Cy5-labeled substrate segments containing DNA triggers and the generation of an amplified fluorescence signal. Moreover, each released DNA trigger can also bind with the hairpin strand to activate and operate the original motor system, which induces further signal amplification via a feedback mechanism. This motor exhibits a 102-fold improvement in detection sensitivity over conventional DNAzyme motors and high selectivity for target mRNA. It has been successfully applied to distinguish cancer cells from normal cells and diagnose tumors in vivo based on mRNA imaging. The proposed DNAzyme motor provides a promising paradigm for the amplified detection and sensitive imaging of low-abundance biomolecules in vivo.

Sensitive and rapid analysis of plasmid DNA topology isoforms by capillary gel electrophoresis with laser induced fluorescence in uncoated capillary.

The work describes the use of SYBR Gold to improve the detection sensitivity of plasmid DNA topoisomers by capillary gel electrophoresis with laser induced fluorescence in an uncoated capillary. The impact of different dyes, including ethidium bromide, SYBR Green and SYBR Gold, was compared based on detection and separation of DNA plasmid topoisomers. Use of SYBR Gold enabled improvement of detection sensitivity by 15-fold while maintaining good separation resolution of the different topoisomers. The baseline dropped with the use SYBR Gold but was overcome by the employment of a capillary with longer ineffective length (40 vs. 20cm). Separation resolution and reproducibility were impacted by the concentration of SYBR Gold and hydroxypropyl methylcellulose. With the use of a short capillary (10cm effective length and 50cm total length), fast separations of supercoiled, linear, open circular, and other isoforms were accomplished within 8min. Appropriate capillary cleaning with 0.1M sodium hydroxide/0.1M hydrochloric acid and capillary storage with 0.1M hydrochloric acid ensured good separation reproducibility of 217 runs during an extended period of use.

MAGIC-DR: An interpretable machine-learning guided approach for acute myeloid leukemia measurable residual disease analysis.

Multiparameter flow cytometry is widely used for acute myeloid leukemia minimal residual disease testing (AML MRD) but is time consuming and demands substantial expertise. Machine learning offers potential advancements in accuracy and efficiency, but has yet to be widely adopted for this application. To explore this, we trained single cell XGBoost classifiers from 98 diagnostic AML cell populations and 30 MRD negative samples. Performance was assessed by cross-validation. Predictions were integrated with UMAP as a heatmap parameter for an augmented/interactive AML MRD analysis framework, which was benchmarked against traditional MRD analysis for 25 test cases. The results showed that XGBoost achieved a median AUC of 0.97, effectively distinguishing diverse AML cell populations from normal cells. When integrated with UMAP, the classifiers highlighted MRD populations against the background of normal events. Our pipeline, MAGIC-DR, incorporated classifier predictions and UMAP into flow cytometry standard (FCS) files. This enabled a human-in-the-loop machine learning guided MRD workflow. Validation against conventional analysis for 25 MRD samples showed 100% concordance in myeloid blast detection, with MAGIC-DR also identifying several immature monocytic populations not readily found by conventional analysis. In conclusion, Integrating a supervised classifier with unsupervised dimension reduction offers a robust method for AML MRD analysis that can be seamlessly integrated into conventional workflows. Our approach can support and augment human analysis by highlighting abnormal populations that can be gated on for quantification and further assessment. This has the potential to speed up MRD analysis, and potentially improve detection sensitivity for certain AML immunophenotypes.

Synthesis and Preclinical Evaluation of Two Novel 68Ga-Labeled Bispecific PSMA/FAP-Targeted Tracers with 2-Nal-Containing PSMA-Targeted Pharmacophore and Pyridine-Based FAP-Targeted Pharmacophore.

Some bispecific radiotracers have been developed to overcome the limitations of monospecific tracers and improve detection sensitivity for heterogeneous tumor lesions. Here, we aim to synthesize two bispecific tracers targeting prostate-specific membrane antigen (PSMA) and fibroblast activation protein (FAP), which are key markers expressed in prostate cancer. A pyridine-based FAP-targeted ligand was synthesized through multi-step organic synthesis and then connected to the 2-Nal-containing PSMA-targeted motif. The Ki(PSMA) values of Ga-complexed bispecific ligands, Ga-AV01084 and Ga-AV01088, were 11.6 ± 3.25 and 28.7 ± 6.05 nM, respectively, and the IC50(FAP) values of Ga-AV01084 and Ga-AV01088 were 10.9 ± 0.67 and 16.7 ± 1.53 nM, respectively. Both [68Ga]Ga-AV01084 and [68Ga]Ga-AV01088 enabled the visualization of PSMA-expressing LNCaP tumor xenografts and FAP-expressing HEK293T:hFAP tumor xenografts in PET images acquired at 1 h post-injection. However, the tumor uptake values from the bispecific tracers were still lower than those obtained from the monospecific tracers, PSMA-targeted [68Ga]Ga-PSMA-617 and FAP-targeted [68Ga]Ga-AV02070. Further investigations are needed to optimize the selection of linkers and targeted pharmacophores to improve the tumor uptake of bispecific PSMA/FAP tracers for prostate cancer imaging.

Simple Binding and Dissociation of a Sialoglycoprotein Using Boronic Acid-Modified Functional Interfaces on Microparticles.

An overexpression of sialic acid is an indicator of metastatic cancer, and selective detection of sialic acid shows potential for cancer diagnosis. Boronic acid is a promising candidate for this purpose because of its ability to specifically bind to sialic acid under acidic conditions. Notably, the binding strength can be easily modulated by adjusting the pH, which allows for a simple dissociation of the bound sialic acid. In this study, we developed 5-boronopicolinic acid (5-BPA)-modified magnetic particles (BMPs) to selectively capture sialic acid biomolecules. We successfully captured fetuin, a well-known sialoglycoprotein, on BMPs at >104 molecules/particle using an acetate buffer (pH 5.0). Facile dissociation then occurred when the system was changed to a pH 7.6 phosphate buffer. This capture-and-release process could be repeated at least five times. Moreover, this system could enrich fetuin by more than 20 times. In summary, BMPs are functional particles for facile purification and concentration through the selective capture of sialic acid proteins and can improve detection sensitivity compared with conventional methods. This technology shows potential for the detection of sialic acid overexpression by biological particles.

High‐Sensitive and Background‐Free Coherent Anti‐Stokes Raman Scattering Microscopy Using Delay Modulation

AbstractCoherent anti‐Stokes Raman scattering (CARS) microscopy has demonstrated a powerful platform for label‐free, non‐invasive, and chemically specific imaging of biological samples. However, the non‐resonant background limits its ability to detect weak Raman signals. Here, an approach to eliminate the non‐resonant background in CARS using delay modulation (DM) is presented, which is enabled by an acousto‐optic modulator and spectral focusing. The results demonstrate that DM‐CARS reduces the non‐resonant background by 10 times and improves detection sensitivity by 100‐fold over normal CARS. It also shows that DM‐CARS has potential applications in tracking heavy water metabolism in bacteria for antimicrobial susceptibility testing and imaging liver tumor tissues. Furthermore, a handheld DM‐CARS device has also demonstrated for in vivo imaging, which can be beneficial in various applications.

High-performance digital shearography integrating spatial light modulator with micro-polarizer camera

Digital shearography (DS), a laser-based optical interferometric method, is widely employed for measuring the first-order derivative of an object's surface deformation. Unlike digital holography, DS integrates self-reference optics, enhancing resistance to environmental disturbance and improving detection sensitivity, making it ideal for non-destructive testing (NDT). DS finds applications in diverse fields such as material inspection, fluid property research, medical diagnostics, cultural heritage restoration, and military defense. The conventional temporal phase-shift (TPS) method encounters limitations in dynamic tests, leading to the introduction of the spatial phase-shift (SPS) method. However, SPS is restricted by aperture size, impacting the phase map quality. The spatial light modulator (SLM) introduces a novel approach to DS system development, enabling quantitative shearing adjustments through precise SLM control. Existing DS systems using traditional phase-shift technology rely on interferometers and struggle to achieve high-quality phase maps with a single exposure. The proposed high-performance DS, leveraging both SLM and a micro-polarizer camera, overcomes this limitation, facilitates single-exposure phase map evaluation with the polarization phase-shift technique, and eliminates the need for a tiny aperture, enhancing light beam utilization and phase map quality.