This study presents a breakthrough in the field of onsite bacterial detection, offering an innovative, rapid, and ultrasensitive colorimetric biosensor for the detection of Escherichia coli (E. coli) O157:H7, using chemically modified melamine foam (MF). Different from conventional platforms, such as 96-well plates and fiber-based membranes, the modified MF features a macroporous reticulated three-dimensional (3D) framework structure, allowing fast and free movement of large biomolecules and bacteria cells through the MF structure in every direction and ensuring good accessibility of entire active binding sites of the framework structure with the target bacteria, which significantly increased sensitive and volume-responsive detection of whole-cell bacteria. The biosensing platform requires less than 1.5 h to complete the quantitative detection with a sensitivity of 10 cfu/mL, discernible by the naked eye, and an enhanced sensitivity of 5 cfu/mL with the help of a smartphone. Following a short enrichment period of 1 h, the sensitivity was further amplified to 2 cfu/mL. The biosensor material is volume responsive, making the biosensing platform sensitivity increase as the volume of the sample increases, and is highly suitable for testing large-volume fluid samples. This novel material paves the way for the development of volume-flexible biosensing platforms for the record-fast, onsite, selective, and ultrasensitive detection of various pathogenic bacteria in real-world applications.

In addition to efficacious vaccines and antiviral therapeutics, reliable and flexible in-home personal use diagnostics for the detection of viral antigens are needed for effective control of the COVID-19 pandemic. Despite the approval of several PCR-based and affinity-based in-home COVID-19 testing kits, many of them suffer from problems such as a high false-negative rate, long waiting time, and short storage period. Using the enabling one-bead-one-compound (OBOC) combinatorial technology, several peptidic ligands with a nanomolar binding affinity toward the SARS-CoV-2 spike protein (S-protein) were successfully discovered. Taking advantage of the high surface area of porous nanofibers, immobilization of these ligands on nanofibrous membranes allows the development of personal use sensors that can achieve low nanomolar sensitivity in the detection of the S-protein in saliva. This simple biosensor employing naked-eye reading exhibits detection sensitivity comparable to some of the current FDA-approved home detection kits. Furthermore, the ligand used in the biosensor was found to detect the S-protein derived from both the original strain and the Delta variant. The workflow reported here may enable us to rapidly respond to the development of home-based biosensors against future viral outbreaks.

The microsomal epoxide hydrolase (mEH) is important in the detoxification of carcinogens in the liver and other tissues but is also a blood biomarker of hepatitis and liver cancer. Improved analytical methods are needed for the study of its role in the metabolism of xenobiotics and endogenous roles as a blood biomarker of diseases. The development of a double nanobody sandwich ELISA offers significant improvements over traditional polyclonal or monoclonal antibody-based assays, enhancing both the homogeneity and the stability of assay production. This study focuses on selecting and optimizing nanobody pairs for detecting human mEH. Four high-affinity nanobodies were identified and tested for thermal stability. Combinations of these nanobodies were evaluated, revealing that the MQ4-MQ30 pair achieved the best performance with a limit of detection (LOD) of 1 ng/mL. Additionally, polyHRP was also employed for signal amplification, enhancing detection capabilities despite challenges related to the small size and single epitope recognition of the nanobodies. Comparative studies using microplates and NHS@MF membranes were also performed. The superior performance of the NHS@MF membranes highlighted their potential as a promising alternative for point-of-care testing. The assay exhibited high specificity for human mEH and minimal cross-reactivity with related enzymes and effectively addressed matrix effects in plasma and tissue samples. These findings underscore the potential of double nanobody sandwich ELISAs for reliable and sensitive biomarker detection.

Personal‐use, naked eye‐readable, low‐cost, highly sensitive, and selective biosensors for rapid detection of environmental toxicants are relevant for many application scenarios. Here, the recent developments of highly sensitive and naked eye distinguishable colorimetric sensors by using commercially available melamine foam (MF) as basic sensing materials for instant and volume‐responsive simultaneous detection of multiple targets in fluid systems are reported. The MF possesses a unique reticulated three‐dimensional (3D) macroporous framework structure enabling rapid mass transfer of large biomolecules through the structures in all directions, ensuring easy access of numerous active binding sites of the chemically modified framework to the proteins and target molecules, and subsequently providing significantly increased sensitive and volume‐responsive detection of target molecules in flowing through sensor systems. Promising results in direct, sandwich, and competitive ELISA tests demonstrated the great application potential of the materials. Besides, an additive and simultaneous detection of two targets in one system is achieved by using different layers of the sensor materials in a flowing‐through filtering device. The novel biosensors are expected to significantly improve the sensitivity and broaden the applications of ELISA in the rapid detections of trace amounts of toxicants in liquid and aerosol systems.

Bone regeneration remains a significant clinical challenge, particularly for large or critical-sized defects caused by trauma, disease, or congenital abnormalities. Mesenchymal stem cells (MSCs) have emerged as a promising cell source for bone tissue engineering, with their osteogenic differentiation playing a crucial role in bone repair. Biomaterials serve as scaffolds that facilitate MSC-mediated bone regeneration by providing structural support and mimicking the extracellular matrix (ECM). This review explores recent advancements in biomaterials designed to promote MSC osteogenesis through two primary approaches: biochemical and physicomechanical stimuli. Therapeutic agent-loaded scaffolds, incorporating growth factors, small molecules, gene materials, peptides, proteins, and extracellular vesicles (EVs), have been extensively studied for their ability to enhance osteogenic differentiation. However, concerns regarding toxicity, off-target effects, and regulatory limitations have led to increasing interest in biomaterials that utilize physicomechanical cues such as stiffness, viscoelasticity, topography, porosity, and dynamic forces (shear stress, compression, vibration) as alternative or complementary strategies. Furthermore, the synergistic effects of multiple physicomechanical cues are being explored to regulate MSC behavior for promoting bone regeneration. This review discusses current challenges, emerging trends, and future directions in the development of next-generation biomaterials that integrate biochemical and physicomechanical approaches for clinical applications in bone repair and regeneration.