Does a novel 3D printed individualized guiding template based on cutaneous fiducial markers contribute to accurate percutaneous insertion of pelvic screws? A preliminary phantom and cadaver study.

BACKGROUND: Most 3D-printed guiding templates require dissection of soft tissues to match the corresponding surfaces of the guiding templates. This study sought to explore the accuracy and acceptability of the novel 3D printed individualized guiding templates based on cutaneous fiducial markers in minimally invasive screw placement for pelvic fractures. METHODS: The printed template was tested on five high-fidelity biomimetic phantom models of the bony pelvis and its surrounding soft tissues as well as on two fresh frozen cadavers. Four cutaneous fiducial markers were transfixed on each phantom model prior to performing CT scans to reconstruct their 3D models. Personalized templates for guiding screw insertion were designed based on the positions of the fiducial markers and virtually planned target screw channels after scanning, followed by 3D printing of the guide. Phase 1 consisted of five expert surgeons inserting one anterograde supra-pubic screw and one sacroiliac screw percutaneously into each phantom model using the 3D-printed guide. The deviation of screw positions between the pre-operative planned and post-operative actual ones was measured after registering their 3D modelling. A Likert scale questionnaire was completed by the expert surgeons to assess their satisfaction and acceptability with the guiding template. Phase 2 consisted of repeating the same procedures on the fresh frozen cadavers in order to demonstrate face, content and concurrent validity. RESULTS: In Phase 1, all ten screws were successfully implanted with the assistance of the guiding template. Postoperative CT scans confirmed that all screws were safely positioned within the bony pelvic channels without breaching the far cortex. The mean longitudinal deviation at the bony entry point and screw tip between the pre-operative planned and post-operative actual screw paths were 2.83 ± 0.60 mm and 3.12 ± 0.81 mm respectively, with a mean angular deviation of 1.25 ± 0.41°. Results from the Likert questionnaire indicated a high level of satisfaction for using the guiding template among surgeons. In Phase 2, results were similar to those in Phase 1. CONCLUSIONS: The 3D-printed guiding template based on cutaneous fiducial markers shows potential for assisting in the accurate insertion of percutaneous screws in the pelvis.

Multi-parameter surface plasmon resonance instrument for multiple nucleic acid quantitative detection.

Multiplex nucleic acid assays can simultaneously detect the characteristics of different target nucleic acids in complex mixtures and are used in disease diagnosis, environmental monitoring, and food safety. However, traditional nucleic acid amplification assays have limitations such as complicated operation, long detection time, unstable fluorescent labeling, and mutual interference of multiplex nucleic acids. We developed a real-time, rapid, and label-free surface plasmon resonance (SPR) instrument for multiplex nucleic acid detection. The multiparametric optical system based on total internal reflection solves the multiplex detection problem by cooperating with linear light source, prism, photodetector, and mechanical transmission system. An adaptive threshold consistency correction algorithm is proposed to solve the problem of inconsistent responsiveness of different detection channels and the inability of quantitative comparison. The instrument achieves label-free and amplification-free rapid detection of these biomarkers for miRNA-21 and miRNA-141, which are widely expressed in breast cancer and prostate cancer. The multiplex nucleic acid detection takes 30 min and the biosensor has good repeatability and specificity. The instrument has a limit of detection (LODs) of 50 nM for target oligonucleotides, and the smallest absolute amount of sample that can be detected is about 4 pmol. It provides a simple and efficient point-of-care testing (POCT) detection platform for small molecules such as DNA and miRNA.

Distinct microbiota dysbiosis in patients with laryngopharynx reflux disease compared to healthy controls.

OBJECTIVE: To compare the differences in the laryngopharynx microbiome between patients with laryngopharyngeal reflux disease (LPRD) and healthy people and further explore the influence of related risk factors pharyngeal microbiome. METHODS: This was a case-control study. Patients with a reflux symptom index (RSI) score > 13 or reflux finding score (RFS) score > 7 were diagnosed with suspected LPRD at the Department of Otolaryngology-Head and Neck Surgery of The 900th Hospital of Joint Logistic Support Force. Patients were assessed using a related risk factors questionnaire survey and examined by electronic naso-laryngoscopy. Simultaneously, laryngopharynx secretions were collected from the patients. The patients received at least eight weeks of proton pump inhibitor therapy, and those who responded were enrolled in the final experimental group. In parallel, laryngopharynx secretions were collected from healthy volunteers as the control group, and the laryngopharynx microbiota were analyzed using second-generation high-throughput sequencing. RESULTS: A total of 23 cases each in the experimental and control group were included in this study. The experimental group microbiota were composed of Streptococcus, Prevotella, Haemophilus, Neisseria, Actinobacillus, Fusobacterium, and Porphyromonas. There was no significant difference in microbial alpha and beta-diversity analysis between the two groups. However, some advantageous bacterium groups were significantly different. The abundance of Prevotella in the experimental group was significantly higher than that of the control group (U = 117, P < 0.05), while the abundance of Fusobacterium (U = 140, P = 0.006) and Porphyromonas (U = 120, P = 0.002) was significantly lower than the control group. Smoking was positively correlated with Pectin (r = 0.46, P = 0.037), Lactobacillus (r = 0.48, P = 0.027), and Clostridium (r = 0.46, P = 0.037), while alcohol was negatively correlated with Streptococcus (r = - 0.5539, P = 0.0092). CONCLUSION: The dominant microflora in the laryngopharynx of LPRD patients was significantly different from that of healthy people, suggesting that the change of laryngopharynx microflora may play an important role in the pathogenesis of LPRD. Smoking, drinking, eating habits, and age correlated with different genus levels of the laryngopharynx microbiota.

Precision insertion of percutaneous sacroiliac screws using a novel augmented reality-based navigation system: a pilot study.

PURPOSE: Augmented reality (AR) enables superimposition of virtual images onto the real world. The aim of this study is to present a novel AR-based navigation system for sacroiliac screw insertion and to evaluate its feasibility and accuracy in cadaveric experiments. METHODS: Six cadavers with intact pelvises were employed in our study. They were CT scanned and the pelvis and vessels were segmented into 3D models. The ideal trajectory of the sacroiliac screw was planned and represented visually as a cylinder. For the intervention, the head mounted display created a real-time AR environment by superimposing the virtual 3D models onto the surgeon's field of view. The screws were drilled into the pelvis as guided by the trajectory represented by the cylinder. Following the intervention, a repeat CT scan was performed to evaluate the accuracy of the system, by assessing the screw positions and the deviations between the planned trajectories and inserted screws. RESULTS: Post-operative CT images showed that all 12 screws were correctly placed with no perforation. The mean deviation between the planned trajectories and the inserted screws was 2.7 ± 1.2 mm at the bony entry point, 3.7 ± 1.1 mm at the screw tip, and the mean angular deviation between the two trajectories was 2.9° ± 1.1°. The mean deviation at the nerve root tunnels region on the sagittal plane was 3.6 ± 1.0 mm. CONCLUSIONS: This study suggests an intuitive approach for guiding screw placement by way of AR-based navigation. This approach was feasible and accurate. It may serve as a valuable tool for assisting percutaneous sacroiliac screw insertion in live surgery.

Development of a surgical navigation system based on augmented reality using an optical see-through head-mounted display.

The surgical navigation system has experienced tremendous development over the past decades for minimizing the risks and improving the precision of the surgery. Nowadays, Augmented Reality (AR)-based surgical navigation is a promising technology for clinical applications. In the AR system, virtual and actual reality are mixed, offering real-time, high-quality visualization of an extensive variety of information to the users (Moussa et al., 2012) [1]. For example, virtual anatomical structures such as soft tissues, blood vessels and nerves can be integrated with the real-world scenario in real time. In this study, an AR-based surgical navigation system (AR-SNS) is developed using an optical see-through HMD (head-mounted display), aiming at improving the safety and reliability of the surgery. With the use of this system, including the calibration of instruments, registration, and the calibration of HMD, the 3D virtual critical anatomical structures in the head-mounted display are aligned with the actual structures of patient in real-world scenario during the intra-operative motion tracking process. The accuracy verification experiment demonstrated that the mean distance and angular errors were respectively 0.809±0.05mm and 1.038°±0.05°, which was sufficient to meet the clinical requirements.

Fragment distance-guided dual-stream learning for automatic pelvic fracture segmentation.

Pelvic fracture is a complex and severe injury. Accurate diagnosis and treatment planning require the segmentation of the pelvic structure and the fractured fragments from preoperative CT scans. However, this segmentation is a challenging task, as the fragments from a pelvic fracture typically exhibit considerable variability and irregularity in the morphologies, locations, and quantities. In this study, we propose a novel dual-stream learning framework for the automatic segmentation and category labeling of pelvic fractures. Our method uniquely identifies pelvic fracture fragments in various quantities and locations using a dual-branch architecture that leverages distance learning from bone fragments. Moreover, we develop a multi-size feature fusion module that adaptively aggregates features from diverse receptive fields tailored to targets of different sizes and shapes, thus boosting segmentation performance. Extensive experiments on three pelvic fracture datasets from different medical centers demonstrated the accuracy and generalizability of the proposed method. It achieves a mean Dice coefficient and mean Sensitivity of 0.935±0.068 and 0.929±0.058 in the dataset FracCLINIC, and 0.955±0.072 and 0.912±0.125 in the dataset FracSegData, which are superior than other comparing methods. Our method optimizes the process of pelvic fracture segmentation, potentially serving as an effective tool for preoperative planning in the clinical management of pelvic fractures.

A bidirectional framework for fracture simulation and deformation-based restoration prediction in pelvic fracture surgical planning.

Pelvic fracture is a severe trauma with life-threatening implications. Surgical reduction is essential for restoring the anatomical structure and functional integrity of the pelvis, requiring accurate preoperative planning. However, the complexity of pelvic fractures and limited data availability necessitate labor-intensive manual corrections in a clinical setting. We describe in this paper a novel bidirectional framework for automatic pelvic fracture surgical planning based on fracture simulation and structure restoration. Our fracture simulation method accounts for patient-specific pelvic structures, bone density information, and the randomness of fractures, enabling the generation of various types of fracture cases from healthy pelvises. Based on these features and on adversarial learning, we develop a novel structure restoration network to predict the deformation mapping in CT images before and after a fracture for the precise structural reconstruction of any fracture. Furthermore, a self-supervised strategy based on pelvic anatomical symmetry priors is developed to optimize the details of the restored pelvic structure. Finally, the restored pelvis is used as a template to generate a surgical reduction plan in which the fragments are repositioned in an efficient jigsaw puzzle registration manner. Extensive experiments on simulated and clinical datasets, including scans with metal artifacts, show that our method achieves good accuracy and robustness: a mean SSIM of 90.7% for restorations, with translational errors of 2.88 mm and rotational errors of 3.18°for reductions in real datasets. Our method takes 52.9 s to complete the surgical planning in the phantom study, representing a significant acceleration compared to standard clinical workflows. Our method may facilitate effective surgical planning for pelvic fractures tailored to individual patients in clinical settings.

An end-to-end geometry-based pipeline for automatic preoperative surgical planning of pelvic fracture reduction and fixation.

Computer-assisted preoperative planning of pelvic fracture reduction surgery has the potential to increase the accuracy of the surgery and to reduce complications. However, the diversity of the pelvic fractures and the disturbance of small fracture fragments present a great challenge to perform reliable automatic preoperative planning. In this paper, we present a comprehensive and automatic preoperative planning pipeline for pelvic fracture surgery. It includes pelvic fracture labeling, reduction planning of the fracture, and customized screw implantation. First, automatic bone fracture labeling is performed based on the separation of the fracture sections. Then, fracture reduction planning is performed based on automatic extraction and pairing of the fracture surfaces. Finally, screw implantation is planned using the adjoint fracture surfaces. The proposed pipeline was tested on different types of pelvic fracture in 14 clinical cases. Our method achieved a translational and rotational accuracy of 2.56 mm and 3.31° in reduction planning. For fixation planning, a clinical acceptance rate of 86.7% was achieved. The results demonstrate the feasibility of the clinical application of our method. Our method has shown accuracy and reliability for complex multi-body bone fractures, which may provide effective clinical preoperative guidance and may improve the accuracy of pelvic fracture reduction surgery.

Biodegradable active composite hydrogel packaging for postharvest climacteric bananas preservation.

Climacteric bananas are susceptible to endogenous ethylene and temperature, resulting in dehydration, accelerated senescence and deterioration. The widely-used plastic cling films is particularly complicated due to their high consumption and non-degradability. Herein, this study proposed to fabricate a carboxymethyl cellulose/polyvinyl alcohol/pyrazoic acid (CPP) hydrogel for postharvest banana preservation. The hydrogel demonstrated excellent potential as a packaging film, including natural degradability (complete degradation within 50 days), high tensile performance, transparent visibility and biosafety. As a validation experiment, bananas in a 30 °C environment confirmed the effectiveness of CPP hydrogels in banana postharvest preservation. Compared with the blank control and CP hydrogel, CPP packaging film delayed the processes of browning, dehydration, softening, nutrients loss, ripening and senescence in bananas, thereby maintaining their commercial value. Accordingly, this study demonstrates the potential of hydrogel materials as an alternative strategy to climacteric fruit preservation and plastic film.

Hierarchically core-shell structured nanocellulose/carbon nanotube hybrid aerogels for patternable, self-healing and flexible supercapacitors.

The flexible and self-healing supercapacitors (SCs) are considered to be promising smart energy storage devices. Nevertheless, the SCs integrated with flexibility, lightweight, pattern editability, self-healing capabilities and desirable electrochemical properties remain a challenge. Herein, an all-in-one self-healing SC fabricated with the free-standing hybrid film (TCMP) composed of the 2,2,6,6-tetramethylpiperidin-1-yloxy-oxidized cellulose nanofibers (TOCNs) carried carbon nanotubes (CNTs), manganese dioxide (MnO2) and polyaniline (PANI) as the electrode, polyvinyl alcohol/sulfuric acid (PVA/H2SO4) gel as the electrolyte and dynamically cross-linked cellulose nanofibers/PVA/sodium tetraborate decahydrate (CNF/PB) hydrogel as the self-healing electrode matrix is developed. The TCMP film electrodes are fabricated through a facile in-situ polymerization of MnO2 and PANI in TOCNs-dispersed CNTs composite networks, exhibiting lightweight, high electrical conductivity, flexibility, pattern editability and excellent electrochemical properties. Benefited from the hierarchically porous structure and high mechanical properties of TOCNs, excellent electrical conductivity of CNTs and the desirable synergistic effect of pseudocapacitance induced by MnO2 and PANI, the assembled SC with an interdigital structure demonstrated a high areal capacitance of 1108 mF cm-2 at 2 mA cm-2, large areal energy density of 153.7 µWh cm-2 at 1101.7 µW cm-2. A satisfactory bending cycle performance (capacitance retention up to 95 % after 200 bending deformations) and self-healing characteristics (∼90 % capacitance retention after 10 cut/repair cycles) are demonstrated for the TCMP-based symmetric SC, delivering a feasible strategy for electrochemical energy storage devices with excellent performance, designable patterns and desirable safe lifespan.

Deformation rate of engineered wood flooring with response surface methodology and adaptive network-based fuzzy inference system.

Controlling the deformation rate is the key to improving the product quality of engineered wood flooring. In this work, the changes in the deformation rate of engineered wood flooring were in focus with cold-pressing, response surface methodology, and adaptive network-based fuzzy inference system were used to explore the relationship between deformation rate and processing parameters, including adhesive spreading rate, pressing time, and pressing pressure. According to the results, the deformation rate was positively related to pressing time, while it increased first and then decreased with both the increase of adhesive spreading rate and pressing pressure. Meanwhile, a mathematical model was developed, and the significant influence of each term on the deformation rate was analyzed. This model had high feasibility and can be used to describe the relationship between the deformation rate and processing parameters. Furthermore, an adaptive network-based fuzzy inference system model was established. It has higher accuracy than that of the response surface methodology model, and it can be used for predicting deformation rate and optimizing processing parameters. Finally, an optimal processing conditions with the lowest deformation rate was determined as follows: 147 g/m2 adhesive spreading rate, 12s pressing time, and 1.2 MPa pressing pressure, and it hope to be adopted in the industrial processing of engineered wood flooring with respective of the higher product quality and lower production costs.

A multi-view interactive virtual-physical registration method for mixed reality based surgical navigation in pelvic and acetabular fracture fixation.

PURPOSE: The treatment of pelvic and acetabular fractures remains technically demanding, and traditional surgical navigation systems suffer from the hand-eye mis-coordination. This paper describes a multi-view interactive virtual-physical registration method to enhance the surgeon's depth perception and a mixed reality (MR)-based surgical navigation system for pelvic and acetabular fracture fixation. METHODS: First, the pelvic structure is reconstructed by segmentation in a preoperative CT scan, and an insertion path for the percutaneous LC-II screw is computed. A custom hand-held registration cube is used for virtual-physical registration. Three strategies are proposed to improve the surgeon's depth perception: vertices alignment, tremble compensation and multi-view averaging. During navigation, distance and angular deviation visual cues are updated to help the surgeon with the guide wire insertion. The methods have been integrated into an MR module in a surgical navigation system. RESULTS: Phantom experiments were conducted. Ablation experimental results demonstrated the effectiveness of each strategy in the virtual-physical registration method. The proposed method achieved the best accuracy in comparison with related works. For percutaneous guide wire placement, our system achieved a mean bony entry point error of 2.76 ± 1.31 mm, a mean bony exit point error of 4.13 ± 1.74 mm, and a mean angular deviation of 3.04 ± 1.22°. CONCLUSIONS: The proposed method can improve the virtual-physical fusion accuracy. The developed MR-based surgical navigation system has clinical application potential. Cadaver and clinical experiments will be conducted in future.

Two-Stage Structure-Focused Contrastive Learning for Automatic Identification and Localization of Complex Pelvic Fractures.

Pelvic fracture is a severe trauma with a high rate of morbidity and mortality. Accurate and automatic diagnosis and surgical planning of pelvic fracture require effective identification and localization of the fracture zones. This is a challenging task due to the complexity of pelvic fractures, which often exhibit multiple fragments and sites, large fragment size differences, and irregular morphology. We have developed a novel two-stage method for the automatic identification and localization of complex pelvic fractures. Our method is unique in that it allows to combine the symmetry properties of the pelvic anatomy and capture the symmetric feature differences caused by the fracture on both the left and right sides, thereby overcoming the limitations of existing methods which consider only image or geometric features. It implements supervised contrastive learning with a novel Siamese deep neural network, which consists of two weight-shared branches with a structural attention mechanism, to minimize the confusion of local complex structures of the pelvic bones with the fracture zones. A structure-focused attention (SFA) module is designed to capture the spatial structural features and enhances the recognition ability of fracture zones. Comprehensive experiments on 103 clinical CT scans from the publicly available dataset CTPelvic1K show that our method achieves a mean accuracy and sensitivity of 0.92 and 0.93, which are superior to those reported with three SOTA contrastive learning methods and five advanced classification networks, demonstrating the effectiveness of identifying and localizing various types of complex pelvic fractures from clinical CT images.

Electrochemically Mediated S-Glycosylation of 1-Thiosugars with Xanthene Derivatives.

An efficient electrochemical dehydrogenative cross-coupling of benzylic C-H bonds with 1-thiosugars at room temperature is described. The direct S-glycosylation protocol avoids using any oxidant, which provides facile access to various glycosylated xanthene derivatives with up to 91% yield. This current electrooxidative reaction is characterized by high atom economy, high efficiency, mild reaction conditions, being environmentally benign, and excellent functional group tolerance. Moreover, preliminary mechanistic investigations reveal that the reaction involves a free radical process.

Microplastic biofilm: An important microniche that may accelerate the spread of antibiotic resistance genes via natural transformation.

Microplastic (MP) biofilms provide a specific microniche for microbial life and are a potential hotspot for the horizontal gene transfer (HGT) of antibiotic resistance genes (ARGs). Nevertheless, the acquisition of ARGs in MP biofilms via natural transformation mediated by extracellular DNA (eDNA) has been rarely explored. This study demonstrated that MP biofilms promoted the natural transformation of extracellular ARGs at the single-cell and multi-species levels, compared to natural substrate (NS) biofilms and bacterioplankton. The transformation frequency on MP biofilms was up to 1000-fold compare to that on NS. The small MPs and aged MPs enhanced the ARG transformation frequencies up to 77.16-fold and 32.05-fold, respectively, compared with the large MPs and pristine MPs. The transformation frequencies on MP biofilms were significantly positively correlated with the bacterial density and extracellular polymeric substance (EPS) content (P < 0.05). Furthermore, MPs significantly increased the expression of the biofilm formation related genes (motA and pgaA) and DNA uptake related genes (pilX and comA) compared to NS and bacterioplankton. The more transformants colonized on MPs contributed to the enhanced transformation frequencies at the community-wide level. Overall, eDNA-mediated transformation in MP biofilms may be an important path of ARG spread, which was promoted by heterogeneous biofilm.

Efficacy of nasal irrigation and oral rinse with sodium bicarbonate solution on virus clearance for COVID-19 patients.

Background: Recent studies have shown that the infectivity of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is reduced under alkaline conditions. The purpose of this study is to assess the effect of nasal irrigation and oral rinse with sodium bicarbonate solution on virus clearance among COVID-19 patients. Materials and methods: COVID-19 patients were recruited and randomly divided into two group, i.e., the experimental group and the control group. The experimental group received regular care plus nasal irrigation and oral rinse with 5% sodium bicarbonate solution, while the control group only received regular care. Nasopharyngeal and oropharyngeal swab samples were collected daily for reverse transcription-polymerase chain reaction (RT-PCR) assays. The negative conversion time and hospitalization time of the patients were recorded, and the results were statistically analyzed. Results: A total of 55 COVID-19 patients with mild or moderate symptoms were included in our study. There was no significant difference in gender, age and health status between the two groups. The average negative conversion time was 1.63 days after treatment with sodium bicarbonate, and the average hospitalization time of the control group and the experimental group were 12.53 and 7.7 days, respectively. Conclusions: Nasal irrigation and oral rinse with 5% sodium bicarbonate solution is effective in virus clearance for COVID-19 patients.

Chemical conversion based on the crystal facet effect of transition metal oxides and construction methods for sharp-faced nanocrystals.

In-depth research has found that the nanocrystal facet of transition metal oxides (TMOs) greatly affects their heterogeneous catalytic performance, as well as the property of photocatalysis, gas sensing, electrochemical reaction, etc. that are all involved in chemical conversion processes. Therefore, the facet-dependent properties of TMO nanocrystals have been fully and carefully studied by combining systematic experiments and theoretical calculations, and mechanisms of chemical reactions are accurately explained at the molecular level, which will be closer to the essence of reactions. Evidently, as an accurate investigation on crystal facets, well-defined TMO nanocrystals are the basis and premise for obtaining relevant credible results, and shape-controlled synthesis of TMO nanocrystals thereby has received great attention and development. The success in understanding of facet-dependent properties and shape-controlled synthesis of TMO nanocrystals is highly valuable for the control of reaction and the design of high-efficiency TMO nanocrystal catalysts as well as other functional materials in practical applications.

Ultrasound Image Guided and Mixed Reality-Based Surgical System With Real-Time Soft Tissue Deformation Computing for Robotic Cervical Pedicle Screw Placement.

OBJECTIVE: Cervical pedicle screw (CPS) placement surgery remains technically demanding due to the complicated anatomy with neurovascular structures. State-of-the-art surgical navigation or robotic systems still suffer from the problem of hand-eye coordination and soft tissue deformation. In this study, we aim at tracking the intraoperative soft tissue deformation and constructing a virtual-physical fusion surgical scene, and integrating them into the robotic system for CPS placement surgery. METHODS: Firstly, we propose a real-time deformation computation method based on the prior shape model and intraoperative partial information acquired from ultrasound images. According to the generated posterior shape, the structure representation of deformed target tissue gets updated continuously. Secondly, a hand tremble compensation method is proposed to improve the accuracy and robustness of the virtual-physical calibration procedure, and a mixed reality based surgical scene is further constructed for CPS placement surgery. Thirdly, we integrate the soft tissue deformation method and virtual-physical fusion method into our previously proposed surgical robotic system, and the surgical workflow for CPS placement surgery is introduced. RESULTS: We conducted phantom and animal experiments to evaluate the feasibility and accuracy of the proposed system. Our system yielded a mean surface distance error of 1.52 ± 0.43 mm for soft tissue deformation computing, and an average distance deviation of 1.04 ± 0.27 mm for CPS placement. CONCLUSION: Results demonstrate that our system involves tremendous clinical application potential. SIGNIFICANCE: Our proposed system promotes the efficiency and safety of the CPS placement surgery.

Do microplastic biofilms promote the evolution and co-selection of antibiotic and metal resistance genes and their associations with bacterial communities under antibiotic and metal pressures?

Microplastic (MP) biofilms with heterogeneous bacterial compositions and structure have become a hotspot of antibiotic resistance genes (ARGs) in aquatic environments. The evolutionary features of ARGs and their related factors including class 1 integron (intI1), metal resistance genes (MRGs), and bacterial communities in MP biofilms under exogenous pressures and how they compared with natural substrates (NS) are unclear. The individual and combined pressures of sulfamethoxazole, tetracycline, and zinc were used to drive the dynamic evolution of ARGs, intI1, MRGs, and bacterial communities in the MP and NS biofilms. The exogenous pressures from the combined selection of sulfamethoxazole, tetracycline, and zinc and their increasing concentrations both significantly enhanced the abundances of ARGs on the MP compared to the NS. Meanwhile, the selective pressures resulted in obvious dissimilarities between the MP and NS bacterial communities. The core bacterial taxa and the co-occurrence patterns of ARGs and bacterial genera in the biofilms of MP and NS were obviously different, and more potential ARG host bacteria selectively colonized the MP. Metal pressure also enhanced the enrichment of ARGs in the MP biofilms by promoting the spread of intI1 via the co-selection mechanism.

Development of bacterial resistance induced by low concentration of two-dimensional black phosphorus via mutagenesis.

The wide use of nano-antibacterial materials has triggered concerns over the development of nanomaterials-associated bacterial resistance. Two-dimensional (2D) black phosphorus (BP) as a new class of emerging 2D nanomaterial has displayed excellent antibacterial performance. However, whether bacteria repeatedly exposed to 2D BP can develop resistance is not clear. We found that wild type E. coli K-12 MG 1655 strains can increase resistance to 2D-BP nanosheets after repeated exposure with subinhibitory concentration of 2D-BP nanosheets. Adaptive morphogenesis including the reinforced barrier function of cell membrane were observed in the resistant bacteria, which enhanced the resistance of bacteria to 2D-BP nanosheets. The whole-genome sequencing analysis showed that the three mutation genes including dmdA, mntP, and gyrA genes were observed in the 2D-BP resistant strains, which controlled catabolism, membrane structure, and DNA replication, respectively. Furthermore, transcriptional sequencing confirmed that these genes related to metabolization, membrane structure, and cell motility were upregulated in the 2D-BP resistant bacteria. The development of resistance to 2D-BP in bacteria mainly attributed to the changes in energy metabolism and membrane structure of bacteria caused by gene mutations. In addition, the up-regulated function of cell motility also helped the bacteria to develop resistance by escaping external stimuli. The results provided new evidence for understanding an important effect of nano-antibacterial materials on the development of bacterial resistance.