Pathological features of vascular wall in Dieulafoy's disease.

AIMS: Although there are many clinical reports on Dieulafoy's disease, there are few studies on the pathological structure of vascular wall in Dieulafoy's disease. METHODS: In this study, the main structural changes of the intima and media of the vascular wall were observed by special staining and immunohistochemical methods in the subjects of Dieulafoy's disease of stomach and intestine. RESULTS: There were many vessels of different sizes in the submucosa, with uneven wall thickness of the vessels. Compared with the normal control group, the content of blue collagen fibers between the vascular smooth muscle cells in the lesion group was increased, the elastic fibers were thickened, and the internal elastic plate was arranged stiff or even interrupted. CONCLUSIONS: The increase of collagen and elastic fibers between the smooth muscle cells of the medium membrane and the destruction of the structure of the inner elastic plate may be the structural basis of vascular lesions leading to Dieulafoy's disease.

A biodegradable, flexible photonic patch for in vivo phototherapy.

Diagnostic and therapeutic illumination on internal organs and tissues with high controllability and adaptability in terms of spectrum, area, depth, and intensity remains a major challenge. Here, we present a flexible, biodegradable photonic device called iCarP with a micrometer scale air gap between a refractive polyester patch and the embedded removable tapered optical fiber. ICarP combines the advantages of light diffraction by the tapered optical fiber, dual refractions in the air gap, and reflection inside the patch to obtain a bulb-like illumination, guiding light towards target tissue. We show that iCarP achieves large area, high intensity, wide spectrum, continuous or pulsatile, deeply penetrating illumination without puncturing the target tissues and demonstrate that it supports phototherapies with different photosensitizers. We find that the photonic device is compatible with thoracoscopy-based minimally invasive implantation onto beating hearts. These initial results show that iCarP could be a safe, precise and widely applicable device suitable for internal organs and tissue illumination and associated diagnosis and therapy.

Bioinspired multifunctional injectable hydrogel for hemostasis and infected wound management.

Routine wound management faces significant challenges including rebleeding and bacterial infection that affect millions of people each year. However, conventional wound dressings (e.g., gauze, bandage) are limited to simply cover the injured surfaces and rarely show special functionality to promote the wound recovery. Currently, injectable hydrogels have been widely designed as multifunctional wound dressings to manage the hemostatic and wound healing process. Nevertheless, the integration of multiple functions through simple composition and easy construction is still difficult and hardly achieved. Herein, we reported a bioinspired multifunctional injectable hydrogel (CQCS@gel) consisted of only two components, catechol-functionalized quaternized chitosan (CQCS) and dibenzaldehyde-terminated poly(ethylene glycol) (DB-PEG2000). The building blocks endowed CQCS@gel with tissue-adhesive, antibacterial, antioxidant, self-healing and pH-responsive properties. Based on the in vivo hemostatic study, quick hemostasis for acute tissue injuries such as liver and carotid wounds was realized owing to the rapid gelation rate and strong tissue-adhesiveness of CQCS@gel. Moreover, CQCS@gel remarkably boosted the chronic recovery process of MRSA-infected cutaneous wounds by promoting collagen deposition, hair follicles regeneration and angiogenesis. Overall, this multifunctional injectable hydrogel shows potentials as a universal wound dressing in clinical applications, enabling both hemostasis and infected wound management. STATEMENT OF SIGNIFICANCE: This is the first report showing the multifunctional injectable hydrogel (CQCS@gel) consisted of catechol-functionalized quaternized chitosan and dibenzaldehyde-terminated poly(ethylene glycol). The incorporation of quaternary ammonium groups imparted the CQCS@gel with outstanding contact-active bacterial killing efficiency and the catechol moieties enhanced its tissue adhesive and antioxidant properties. Moreover, the reversible imine crosslinks endowed the CQCS@gel with self-healing and pH-responsive drug release capabilities. These multiple functions were integrated into a single injectable hydrogel system with easy availability and low cost. In vitro and in vivo results showed that the newly designed hydrogel was biocompatible, realized successful sealing hemostasis under multiple bleeding scenarios and enabled accelerated healing of infected skin wounds.

Multistimuli-Responsive PNIPAM-Based Double Cross-Linked Conductive Hydrogel with Self-Recovery Ability for Ionic Skin and Smart Sensor.

Multistimuli-responsive conductive hydrogels have been appealing candidates for multifunctional ionic skin. However, the fabrication of the multistimuli-responsive conductive hydrogels with satisfactory mechanical property to meet the practical applications is still a great challenge. In this study, a novel poly(N-isopropylacrylamide-co-sodium acrylate)/alginate/hectorite clay Laponite XLS (PNIPAM-SA/ALG/XLS) double cross-linked hydrogel with excellent mechanical property, self-recovery ability, temperature/pH-responsive ability, and strain/temperature-sensitive conductivity was fabricated. The PNSAX hydrogel possessed a moderate tensile strength of 290 kPa at a large elongation rate of 1120% and an excellent compression strength of 2.72 MPa at 90%. The hydrogel also possessed excellent mechanical repeatability and self-recovery ability. Thus, the hydrogel could withstand repetitive deformations for long time periods. Additionally, the hydrogel could change its transparency and volume once at a temperature of 44 °C and change its volume at different pHs. Thus, the visual temperature/pH-responsive ability allowed the hydrogel to qualitatively harvest environmental information. Moreover, the hydrogel possessed an excellent conductivity of 0.43 S/m, and the hydrogel could transform large/subtle deformation and temperature information into electrical signal change. Thus, the ultrafast strain/temperature-sensitive conductivity allowed the hydrogel to quantitatively detect large/small-scale human motions as well as environmental temperature. A cytotoxicity test confirmed the good cytocompatibility. Taken together, the hydrogel was suitable for human motion detecting and environmental information harvesting for long time periods. Therefore, the hydrogel has a great application potential as a multifunctional ionic skin and smart sensor.

Bactericidal Anti-Adhesion Potential Integrated Polyoxazoline/Silver Nanoparticle Composite Multilayer Film with pH Responsiveness.

Bacterial infections occur frequently during the implantation of medical devices, and functional coating is one of the effective means to prevent and remove biofilms. In this study, three different hydrophilic polyoxazolines with carboxyl groups (aPOx: PT1, PT2 and PT3) and bactericidal silver nanoparticles (AgNPs) were synthesized successfully, and an aPOx-AgNP multilayer film was prepared by electrostatic layer-by-layer self-assembly. The effect of charge density and assembly solution concentration was explored, and the optimal self-assembly parameters were established (PT2 1 mg/mL and AgNPs 3 mg/mL). The hydrophilicity of the surface can be enhanced to resist protein adhesion if the outermost layer is aPOx, and AgNPs can be loaded to kill bacteria, thereby realizing the bactericidal anti-adhesion potential integration of the aPOx-AgNP multilayer film. In addition, the aPOx-AgNP multilayer film was found to have the characteristic of intelligent and efficient pH-responsive silver release, which is expected to be used as a targeted anti-biofilm surface of implantable medical devices.

Dually Responsive Nanoparticles for Drug Delivery Based on Quaternized Chitosan.

In this work, we report the fabrication and functional demonstration of a kind of dually responsive nanoparticles (NPs) as a potential drug delivery vector. The pH value, corresponding to the acidic microenvironment at the tumor site, and mannitol, to the extracellular trigger agent, were employed as the dually responsive factors. The function of dual responses was achieved by breaking the dynamic covalent bonds between phenylboronic acid (PBA) groups and diols at low pH value (pH 5.0) and/or under the administration of mannitol, which triggered the decomposition of the complex NPs and the concomitant release of anticancer drug of doxorubicin (DOX) loaded inside the NPs. The NPs were composed of modified chitosan (PQCS) with quaternary ammonium and PBA groups on the side chains, heparin (Hep), and poly(vinyl alcohol) (PVA), in which quaternary ammonium groups offer the positive charge for the cell-internalization of NPs, PBA groups serve for the formation of dynamic bonds in responding to pH change and mannitol addition, PVA furnishes the NPs with diol groups for the interaction with PBA groups and the formation of dynamic NPS, and Hep plays the roles of reducing the cytotoxicity of highly positively-charged chitosan and forming of complex NPs for DOX up-loading. A three-step fabrication process of drug-loaded NPs was described, and the characterization results were comprehensively demonstrated. The sustained drug release from the drug-loaded NPs displayed obvious pH and mannitol dependence. More specifically, the cumulative DOX release was increased more than 1.5-fold at pH 5.0 with 20 mg mL-1 mannitol. Furthermore, the nanoparticles were manifested with effective antitumor efficient and apparently enhanced cytotoxicity in response to the acidic pH value and/or mannitol.

A chitosan hydrogel sealant with self-contractile characteristic: From rapid and long-term hemorrhage control to wound closure and repair.

Emergent and long-term hemorrhage control is requisite and beneficial for reducing global mortality and postoperative complications (e.g., second bleeding and adverse tissue adhesion). Despite recent advance in injectable hydrogels for hemostasis, achieving rapid gelation, strong tissue-adhesive property and stable mechanical strength under fluid physiological environment is still challenging. Herein, we developed a novel chitosan hydrogel (CCS@gel) via dynamic Schiff base reaction and mussel-inspired catechol chemistry. The hydrogel possessed high gelation rate (<10 s), strong wet adhesiveness, excellent self-healing performance and biocompatibility. More importantly, the CCS@gel exhibited saline-induced contractile performance and mechanical enhancement, promoting its mechanical property in moist internal conditions. In vivo studies demonstrated its superior hemostatic efficacy for diverse anticoagulated visceral and carotid bleeding scenarios, compared to commercialized fibrin glue. The hydrogel-treated rats survived for 8 weeks with minimal inflammation and postoperative adhesion. These results revealed that the promising CCS@gel would be a facile, efficient and safe sealant for clinical hemorrhage control.

Ultrastretchable, self-adhesive, strain-sensitive and self-healing GO@DA/Alginate/P(AAc-co-AAm) multifunctional hydrogels via mussel-inspired chemistry.

For conductive hydrogels applied in biosensors, wearable devices and so forth, multifunctionality is an inevitable trend of development to meet various practical requirements and enhance human experience. Herein, inspired by nanocomposite, double-network (DN) and mussel chemistry, a new Graphene oxide@Dopamine/Alginate/Poly(acrylic acid-co-acrylamide) [GO@DA/Alginate/P(AAc-co-AAm)] hydrogel was fabricated through one-pot in-situ radical copolymerization. GO@DA nanofillers, prepared via GO confined DA polymerization, imparted the hydrogel with remarkable adhesiveness. Alginate/P(AAc-co-AAm) DN matrix, physically and chemically crosslinked by Fe3+ and N,N'-Methylenebisacrylamide, made hydrogels ultrastretchable, self-healing and biocompatible. With contents of DA and alginate accurately regulated, the tensile strength, elongation, adhesion strength and conductivity of the optimal hydrogel could reach 320.2 kPa, 1198 %, 36.9 kPa and 3.24 ± 0.12 S/m, respectively. What's more notable was that the synergistic integration of repeatable adhesiveness, strain sensitivity, use stability, self-healing ability and biocompatibility provided such hydrogels with tremendous possibility of practical application for strain sensors.

Sugar-Based Aggregation-Induced Emission Luminogens: Design, Structures, and Applications.

Sugars are abundant natural sources existing in biological systems, and bioactive saccharides have attracted much more attention in the field of biochemistry and biomaterials. For better understanding of the sugar-based biomaterials and biological sciences, aggregation-induced emission luminogens (AIE-gens) have been widely employed for detection, tracing, and imaging. This review covers the applications of AIE molecules on sugar-based biomaterials by three parts, polysaccharide, oligosaccharide, and monosaccharide, mainly focusing on saccharide detection, stimuli response materials preparation, bioimaging, and study of the AIE mechanism. These excellent works suggest the promising future of the sugar-based AIE bioconjugates, considering that the naturally designed and elaborately functionalized saccharides play discriminate roles in biological processes and AIE-tagged species may work as an indicator in each case. However, there are a lot of sugar-based biological species that have not been touched, such as mucopolysaccharides and glycoproteins on the cell surface and in the cell plasma. Based on these features, we enthusiastically look forward to more glorious developments in this bright research area.

Carbohydrate response element binding protein (ChREBP) correlates with colon cancer progression and contributes to cell proliferation.

Cancers are characterized by reprogrammed glucose metabolisms to fuel cell growth and proliferation. Carbohydrate response element binding protein (ChREBP) is a glucose-mediated transcription factor that strongly regulates glycolytic and lipogenic pathways. It has been shown to associate with metabolic diseases, such as obesity, diabetes and non-alcoholic fatty liver diseases. However, how it associates with cancers has not been well understood. In this study, ChREBP expression was assessed by immunohistochemistry in colon tissue arrays containing normal colon tissue and cancer tissue at different clinical stages. Tissue mRNA levels of ChREBP were also measured in a cohort of colon cancer patients. We found that ChREBP mRNA and protein expression were significantly increased in colon cancer tissue compared to healthy colon (p < 0.001), and their expression was positively correlated to colon malignancy (for mRNA, p = 0.002; for protein p < 0.001). Expression of lipogenic genes (ELOVL6 and SCD1) in colon cancer was also positively associated with colon malignancy (for both genes, p < 0.001). In vitro, ChREBP knockdown with siRNA transfection inhibited cell proliferation and induced cell cycle arrest without changes in apoptosis in colon cancer cell lines (HT29, DLD1 and SW480). Glycolytic and lipogenic pathways were inhibited but the p53 pathway was activated after ChREBP knockdown. Taken together, ChREBP expression is associated with colon malignancy and it might contribute to cell proliferation via promoting anabolic pathways and inhibiting p53. In addition, ChREBP might represent a novel clinical useful biomarker to evaluate the malignancy of colon cancer.

Cationic quaternized chitosan bioconjugates with aggregation-induced emission features for cell imaging.

Fluorescent bioprobs are in urgent demand to monitor important biological events in biomedicine. However, the aggregation-caused quenching character, high toxicity, water-insolubility and easy leakage property of conventional small molecular dyes hinder the development in this area. In this work, an aggregation-induced emission (AIE) bioconjugate was synthesised by labeling tetraphenylethylene (TPE) to quaternized chitosan (QCS). The TPE-QCS bioconjugate emits strong fluorescence even in solid state, and is cationic and water-soluble over a wide range of pH values. The TPE-QCS aqueous solution stained HeLa cells by dose- and time-depent manner and imaged living cells with bright fluorescence. Futhermore, the cationic bioconjugate was readily internalized by cells through endocytosis, and further aggragated to large sizes and adhered to negatively charged organelle membranes inside cells achieving fluorescent cell imaging with fluorescence enhancement and leakage-free staining. The AIE-active TPE-QCS with cationic nature, good water-solubility over a wide pH range and unique cell imaging properties could trace HeLa cells for as long as 23 passages, that was obviously superior to existing commercial cellular tracer, so has promising application prospects as ultra long-term tracer in biomedical field.

Expressions of Carbohydrate Response Element Binding Protein and Glucose Transporters in Liver Cancer and Clinical Significance.

Carbohydrate response element binding protein (ChREBP) is a glucose-sensing transcription factor that mediates the induction of glycolytic and lipogenic genes in response to glucose. We investigated the expression patterns of ChREBP and glucose transporters (GLUTs) in human hepatocellular carcinoma (HCC) and their association with HCC progression. ChREBP, GLUT2 and GLUT1 immunohistochemistry were performed on liver tissue array containing normal liver tissue, HCC adjacent tissue and cancer tissue of different HCC stages. The effect of HCC malignancy on protein expression was analyzed with one-way ANOVA. The correlations between protein expressions were analyzed with Pearson Correlation test. We found that ChREBP protein expression tended to be positively correlated to liver malignancy. GLUT2 protein expression was significantly reduced in human HCC as compared to normal liver tissue and its expression in HCC was inversely associated to malignancy (p < 0.001). In contrast, GLUT1 was significantly increased in cancer cells and its expression was positively correlated to malignancy (p < 0.001). Furthermore, GLUT1 expression was positively associated to ChREBP expression (r = 0.481, p < 0.0001, n = 70) but negatively correlated to GLUT2 expression (r = -0.320, p = 0.007, n = 70). Notably, ChREBP-expressing hepatocytes did not express GLUT2 but GLUT1. This is the first report unveiling expressions of ChREBP and GLUT2/GLUT1 and their relations in HCC. The expression patterns are related to malignancy and this information would facilitate evaluation of clinical behavior and treatment of HCC.

High strength graphene oxide/chitosan composite screws with a steel-concrete structure.

Due to the biocompatibility, biodegradability and numerous resources of chitosan (CS), CS screws attract much more attention, as a new generation of internal fixation devices. Herein, a facile solution-casting method was utilized to fabricate CS composite screws with a steel-concrete structure by combining graphene oxide (GO) and CS fiber bundles. The embedding GO endowed CS screws with a Honeycomb-Cobweb network. And CS screws reinforced with CS fiber bundles of four arrangement sequences could endure different degrees of external force. The optimal arrangement type of CS fiber bundles (the linear type) and addition amount of GO (0.15 wt%) was utilized to construct the steel-concrete structure. Due to the mechanical interlocking between the GO/CS matrices and CS fiber bundles, the bending strength of CS composite screws, with such an unusual structure, could reach high up to 378 MPa, approximately 1.88 times the blank control group was. The findings stand out as a new tool to prepare high bending strength screws and the steel-concrete structure might be used effectively in more critical load-bearing situations.

Highly mineralized chitosan-based material with large size, gradient mineral distribution and hierarchical structure.

Nature materials constituted with organic and inorganic components have hierarchical structure and superior performance. Although a variety of techniques have been developed to mimic microstructure and properties of natural mineralized materials, facile and rapid fabrication of large-size bulk materials with high calcium content under ambient conditions still remains a major challenge. Here, we present a feasible and versatile route to a highly mineralized material with an in situ preparation method where gelation and mineralization occur simultaneously. Meanwhile, hierarchically ordered hydrogel microstructures are formed during the gelation, and controllable inorganic gradient distribution forms along with mineralization spontaneously. With the achievement of high mineral content by the assistance of urea, this fabrication route is facile and efficient, only taking several hours to complete the gelation and mineralization, and large-scale materials are prepared readily. This chitosan matrix-directed mineralization represents a rational and promising strategy for fast fabrication of highly mineralized material with hierarchical structure on a large scale, and the chitosan-based mineralized material has great potential for applications in bone repairing and tissue engineering.

Construction of ordered structure in polysaccharide hydrogel: A review.

Hydrogels are three-dimensional, hydrophilic, polymeric networks, held together by a variety of physical or chemical crosslinks. Among the numerous polymers that can be employed to fabricate hydrogel, polysaccharides have attracted enormous attention due to their peculiar properties that make them suitable for various applications. Compared with homogeneous hydrogels, hydrogels with ordered structures on various length scales are endowed with excellent properties and promising applications in materials science. In the present review, a wide range of techniques were introduced and discussed, which had been utilized to construct ordered hierarchical structures in polysaccharide hydrogels. These techniques focused on the construction of multi-layered and orientated structure, which are two typical and very important forms of hierarchical structure.

An asymmetric chitosan scaffold for tendon tissue engineering: In vitro and in vivo evaluation with rat tendon stem/progenitor cells.

The poor healing capacity and typically incomplete regeneration of injured tendons has made tendon repair as a primary clinical concern. Several methods for repairing injured tendons have been developed in the last decade. Tendon regeneration using current tissue engineering techniques requires advanced biomaterials to satisfy both microstructural and mechanical criteria. In this study, a novel chitosan (CS)-based scaffold with asymmetric structure was fabricated using a self-deposition technique. The fabricated scaffolds were assessed with regard to the microstructural and mechanical demands of cell ingrowth and the prevention of peritendinous adhesion. In vitro studies showed that rat tendon stem/progenitor cells (TSPCs) seeded onto the CS scaffold displayed higher levels of tenogenic specific genes expression and protein production. Four and six weeks after the implantation of CS scaffolds on full-site Achilles tendon defects, in vivo tendon repair was evaluated by histology, immunohistochemistry, immunofluorescence, and mechanical measurements. The production of collagen I (COL1) and collagen III (COL3) demonstrated that the CS scaffolds were capable of inducing conspicuous tenogenic differentiation, higher tenomodulin (TNMD) production, and superior phenotypic maturity, compared with the empty defect group. The introduction of TSPCs into the CS scaffold resulted in a synergistic effect on tendon regeneration and yielded better-aligned collagen fibers with elongated, spindle-shaped cells. These findings indicated that the application of TSPC-seeded CS scaffolds would be a feasible approach for tendon repair. STATEMENT OF SIGNIFICANCE: The poor healing capacity of injured tendons and inevitable peritendinous adhesion has made tendon regeneration a clinical priority. In this study, an asymmetric chitosan scaffold was developed to encapsulate rat tendon stem/progenitor cells (TSPCs), which could induce higher levels of tenogenic specific genes and protein expression. Remarkably, the introduction of TSPCs into the asymmetric chitosan scaffold generated a synergistic effect on in vivo tendon regeneration and lead to better-aligned collagen fibers compared with asymmetric chitosan scaffold alone. This work can provide new guidelines for the structure and property design of cell-seeded scaffolds for tendon regeneration.

Norcrassin A, a novel C16 tetranorditerpenoid, and bicrotonol A, an unusual dimeric labdane-type diterpenoid, from the roots of Croton crassifolius.

A novel C16 tetranorditerpenoid, norcrassin A (1), and an unusual dimeric labdane-type diterpenoid, bicrotonol A (2), were isolated from the roots of Croton crassifolius. Norcrassin A (1) featured a new carbon skeleton with an unprecedented 5/5/5/6 tetracyclic system. Bicrotonol A (2) possessed an unusual tetrahydroxypyran ring linkage connecting two labdane diterpenoid monomers. The structures of all compounds, including the absolute configuration, were elucidated by the interpretation of their NMR spectroscopic data, high resolution mass spectrometry, and single-crystal X-ray diffraction. A plausible biosynthetic pathway of 1 is proposed. The anti-Alzheimer's Disease (AD) activities of 1 and 2 are also evaluated using the AD pathological model.

BMP-2 plasmid DNA-loaded chitosan films - A new strategy for bone engineering.

OBJECTIVES: Bone defects are common in every area of medicine and remain a clinical challenge. Tissue engineering has led to promising new strategies in accelerating bone repair. Bone morphogenetic proteins (BMPs) play crucial roles in bone regeneration, but are required in supra-physiological doses, which are expensive and produce severe side effects. METHODS: To address these issues, we prepared BMP-2 plasmid DNA-loaded chitosan films, and examined their effects on mouse osteoblast-like MC3T3-E1 cell morphology, proliferation, and runt-related transcription factor 2 (RUNX2) expression. In vivo testing was performed using calvarial critical-sized defects and histomorphometry in 36 Sprague-Dawley rats. Unloaded chitosan films and empty defects served as controls. RESULTS: In contrast to the controls, cells grown on BMP-2 plasmid DNA-loaded chitosan films had well established filopodia and lamellipodia, significantly higher proliferation 2, 4, and 6 days post-seeding (P ≤ 0.05), and higher nuclear RUNX2 expression. In vivo, new bone growth was significantly greater in the BMP-2 group than in the control groups at 4, 8, and 12 weeks (P ≤ 0.01). CONCLUSIONS: Based on our study findings, BMP-2 plasmid DNA-loaded chitosan films provide an effective strategy for GBR, combining cellular compatibility with biocapability in vivo.

Cytotoxic and antibacterial activities of iridoids and sesquiterpenoids from Valeriana jatamansi.

Three new iridoids, valejatanins A-C (1-3), and one new natrual iridoid (4), together with four known sesquiterpenoids (5-8), were isolated from the roots of Valeriana jatamansi Jones. Compounds 3 and 4 are C(4)-epimers. Their structures were elucidated by extensive spectroscopic analysis (IR, HRESIMS, 1D and 2D NMR) and by comparison of their NMR data with those of related compounds. The absolute configuration of 5 was determined for the first time by single-crystal X-ray diffraction analysis with Cu-Kα irradiation. The cytotoxic activities of all compounds were evaluated against HT29, K562 and B16 cancer cell lines in vitro by MTT assay. Valejatanin A (1) showed noteworthy cytotoxic activities with IC50 values of 22.17, 15.26, 3.53µg/mL against three cancer cell lines. The antibacterial activities of all compounds against bacteria were tested in vitro. Compound 6 exhibited antibacterial activities against Staphylococcus aureus and Pseudomonas aeruginosa.

Catechol-Functional Chitosan/Silver Nanoparticle Composite as a Highly Effective Antibacterial Agent with Species-Specific Mechanisms.

In this study, silver nanoparticles (Ag NPs) coated with catechol-conjugated chitosan (CSS) were prepared using green methods. Interestingly, we uncovered that CSS-coated Ag NPs (CSS-Ag NPs) exhibited a higher toxicity against gram-negative Escherichia coli (E. coli) bacteria than against gram-positive Staphylococcus aureus (S. aureus) bacteria. The differences revealed that the CSS-Ag NPs killed gram bacteria with distinct, species-specific mechanisms. The aim of this study is to further investigate these underlying mechanisms through a series of analyses. The ultrastructure and morphology of the bacteria before and after treatment with CSS-Ag NPs were observed. The results demonstrated the CSS-Ag NPs killed gram-positive bacteria through a disorganization of the cell wall and leakage of cytoplasmic content. In contrast, the primary mechanism of action on gram-negative bacteria was a change in membrane permeability, induced by adsorption of CSS-Ag NPs. The species-specific mechanisms are caused by structural differences in the cell walls of gram bacteria. Gram-positive bacteria are protected from CSS-Ag NPs by a thicker cell wall, while gram-negatives are more easily killed due to an interaction between a special outer membrane and the nanoparticles. Our study offers an in-depth understanding of the antibacterial behaviors of CSS-Ag NPs and provides insights into ultimately optimizing the design of Ag NPs for treatment of bacterial infections.