Polystyrene nanoplastics at predicted environmental concentrations enhance the toxicity of copper on Caenorhabditis elegans.

Excessive nanoplastics not only pose a direct threat to the environment but also have the propensity to adsorb and interact with other pollutants, exacerbating their impact. The coexistence of nanoplastics and heavy metals in soils is a prevalent phenomenon. However, limited research existed about the joint effects of the two contaminants on soil organisms. In this paper, we ascertained the combined toxicity of polystyrene nanoplastics (PS-NPs) and copper (Cu2+) on soil organisms (Caenorhabditis elegans) at quantities that were present in the environment, further exploring whether the two toxicants were synergistic or antagonistic. The outcomes manifested that single exposure to low-dose PS-NPs (1 µg/L) would not cause significant damage to nematodes. After treatment with PS-NPs and Cu2+, the locomotion ability of nematode was impaired, accompanied by an elevation in reactive oxygen species (ROS) level and a biphasic response in antioxidant enzyme activity. Moreover, combined exposure to PS-NPs and Cu2+ induced the mRNA up-regulation of vit-6, cyp-35a2, hsp-16.2, age-1, and cep-1, both of which were stress-related genes. The comparative analysis between groups (with or without PS-NPs) revealed that the combined exposure group resulted in significantly greater toxic effects on nematodes compared with Cu2+ exposure alone. Furthermore, the addition of PS-NPs influenced the metabolic profiles of Caenorhabditis elegans under Cu2+ stress, with numerous differential metabolites associated with oxidative damage or defense mechanism. Overall, these findings manifested that PS-NPs at the expected environmental concentration elevated Cu2+ toxicity on nematodes.

A PDMS-Agar Hybrid Microfluidic Device for the Investigation of Chemical-Mechanical Associative Learning Behavior of C. elegans.

Associative learning is a critical survival trait that promotes behavioral plasticity in response to changing environments. Chemosensation and mechanosensation are important sensory modalities that enable animals to gather information about their internal state and external environment. However, there is a limited amount of research on these two modalities. In this paper, a novel PDMS-agar hybrid microfluidic device is proposed for training and analyzing chemical-mechanical associative learning behavior in the nematode Caenorhabditis elegans. The microfluidic device consisted of a bottom agar gel layer and an upper PDMS layer. A chemical concentration gradient was generated on the agar gel layer, and the PDMS layer served to mimic mechanical stimuli. Based on this platform, C. elegans can perform chemical-mechanical associative learning behavior after training. Our findings indicated that the aversive component of training is the primary driver of the observed associative learning behavior. In addition, the results indicated that the neurotransmitter octopamine is involved in regulating this associative learning behavior via the SER-6 receptor. Thus, the microfluidic device provides a highly efficient platform for studying the associative learning behavior of C. elegans, and it may be applied in mutant screening and drug testing.

Rapid Assembly of Cellulose Microfibers into Translucent and Flexible Microfluidic Paper-Based Analytical Devices via Wettability Patterning.

Microfluidic paper-based analytical devices (µPADs) are emerging as powerful analytical platforms in clinical diagnostics, food safety, and environmental protection because of their low cost and favorable substrate properties for biosensing. However, the existing top-down fabrication methods of paper-based chips suffer from low resolution (>200 µm). Additionally, papers have limitations in their physical properties (e.g., thickness, transmittance, and mechanical flexibility). Here, we demonstrate a bottom-up approach for the rapid fabrication of heterogeneously controlled paper-based chip arrays. We simply print a wax-patterned microchip with wettability contrasts, enabling automatic and selective assembly of cellulose microfibers to construct predefined paper-based microchip arrays with controllable thickness. This paper-based microchip printing technology is feasible for various substrate materials ranging from inorganic glass to organic polymers, providing a versatile platform for the full range of applications including transparent devices and flexible health monitoring. Our bottom-up printing technology using cellulose microfibers as the starting material provides a lateral resolution down to 42 ± 3 µm and achieves the narrowest channel barrier down to 33 ± 2 µm. As a proof-of-concept demonstration, a flexible paper-based glucose monitor is built for human health care, requiring only 0.3 µL of sample for testing.

A magnet-actuated microfluidic array chip for high-throughput pretreatment and amplification and detection of multiple pathogens.

The outbreak of global infectious diseases has posed a significant threat to public health, requiring the rapid and accurate diagnosis of pathogens promptly for the society to implement immediate control measures to prevent widespread pandemics. In this work, a magnet-actuated microfluidic array chip (MMAC) is developed with integrated sample processing and nucleic acid amplification for the rapid detection of multiple pathogens by loop-mediated isothermal amplification. In comparison to previous works, where fluid control was dependent on external equipment or finger-based manual pressing, the fluid control of the MMAC is realized by magnetically actuating a ferric oxide (Fe3O4) doped polydimethylsiloxane (PDMS) layer that separates the sample from the LAMP reagent in a high-throughput manner, which not only reduces the complexity of fluid control but also enhances the repeatability of detection by eliminating variations in operation by different users. Examination with a testing sample containing Salmonella typhimurium and Escherichia coli showed high specificity for pathogen detection without cross-contamination. The lowest detection concentration was 5.2 copies per µL for Salmonella typhimurium with a detection time of 60 min. The proposed method demonstrated the simultaneous detection of multiple pathogens, which is potentially helpful in applications of immediate diagnosis.

Tissue Engineering in Stomatology: A Review of Potential Approaches for Oral Disease Treatments.

Tissue engineering is an emerging discipline that combines engineering and life sciences. It can construct functional biological structures in vivo or in vitro to replace native tissues or organs and minimize serious shortages of donor organs during tissue and organ reconstruction or transplantation. Organ transplantation has achieved success by using the tissue-engineered heart, liver, kidney, and other artificial organs, and the emergence of tissue-engineered bone also provides a new approach for the healing of human bone defects. In recent years, tissue engineering technology has gradually become an important technical method for dentistry research, and its application in stomatology-related research has also obtained impressive achievements. The purpose of this review is to summarize the research advances of tissue engineering and its application in stomatology. These aspects include tooth, periodontal, dental implant, cleft palate, oral and maxillofacial skin or mucosa, and oral and maxillofacial bone tissue engineering. In addition, this article also summarizes the commonly used cells, scaffolds, and growth factors in stomatology and discusses the limitations of tissue engineering in stomatology from the perspective of cells, scaffolds, and clinical applications.

Integrated and finger-actuated microfluidic chip for point-of-care testing of multiple pathogens.

The integration of gel-based loop-mediated isothermal amplification (gLAMP) and finger-actuated microfluidic chip (µFAchip) was developed for the simultaneous detection of various different types of bacterial pathogens. The developed µFAchip consisted of three PDMS layers attached together by two adhesive tapes. Multiple chambers in the top PDMS layer were used for sample preparation, and the corresponding chambers in the bottom PDMS layer was used for long-term storage of LAMP reagents without DNA templates. The thin PDMS layer in the middle contained cross-shaped cuts as finger-actuated valves for fluid control. To reduce operation steps on the chip, such as pipetting and manipulation of samples, Whatman CloneSaver card was pre-embedded in the top chambers for on-chip DNA extraction and purification. Upon a simple press on the top layer, the finger-actuated valve was opened up, allowing DNA samples on the top layer flow into the bottom reaction chambers for gLAMP reaction. For POCT applications, on-chip LAMP reaction and imaging were conducted on a miniaturized peltier heater and a portable fluorescence imaging system respectively. Under the optimized condition, multiple pathogens were detected simultaneously with high selectivity and sensitivity (as low as 1.6 cells). The developed µFAchip provided a rapid and easy-to-operate platform for gLAMP-based pathogen detection, with the potential for in-field detection, especially in areas with limited resources.

Carbohydrate-protein template synthesized high mannose loading gold nanoclusters: A powerful fluorescence probe for sensitive Concanavalin A detection and specific breast cancer cell imaging.

Protein-encapsulated gold nanoclusters (Au NCs) have recently gained much attention in biosensing and bioimaging applications owing to their remarkable fluorescence properties, nontoxicity and good biocompatibility. In this work, the mannose was grafted onto the bovine serum albumin (BSA) encapsulated Au NCs (BSA-Au NCs) to produce a mannose functionalized BSA-Au NCs (Man-BSA-Au NCs) as a new fluorescence probe for Concanavalin A (Con A) detection and human breast cancer cell imaging. A new strategy with mannose-BSA conjugates as template was firstly applied for the synthesis of Man-BSA-Au NCs, leading to a high loading of mannose (767.6 ± 7.2 mg/L) onto BSA-Au NCs. The as-prepared Man-BSA-Au NCs showed advantages of facile preparation, good monodispersity and strong red-emission. Notably, aggregation-induced fluorescence quenching of Man-BSA-Au NCs was triggered by Con A due to the multivalent cooperative interactions between mannose and Con A, which was subsequently confirmed by MALDI-TOF MS. Hence highly selective and sensitive fluorescence detection of Con A was achieved by using Man-BSA-Au NCs as a fluorescence sensor. A good linear relationship was obtained over the range of 0.01-1 µM (R2 = 0.994) with a detection limit of 0.62 nM (S/N = 3). The developed sensor was then applied to determine Con A in human serum with acceptable recoveries of 93.70-104.8%. Moreover, based on the specific recognition between mannose and overexpressed mannose receptors on human breast cancer cells, the Man-BSA-Au NCs were successfully utilized for cancer cell imaging with good specificity.