Biomaterials science and surface engineering strategies for dental peri-implantitis management.

Peri-implantitis is a bacterial infection that causes soft tissue inflammatory lesions and alveolar bone resorption, ultimately resulting in implant failure. Dental implants for clinical use barely have antibacterial properties, and bacterial colonization and biofilm formation on the dental implants are major causes of peri-implantitis. Treatment strategies such as mechanical debridement and antibiotic therapy have been used to remove dental plaque. However, it is particularly important to prevent the occurrence of peri-implantitis rather than treatment. Therefore, the current research spot has focused on improving the antibacterial properties of dental implants, such as the construction of specific micro-nano surface texture, the introduction of diverse functional coatings, or the application of materials with intrinsic antibacterial properties. The aforementioned antibacterial surfaces can be incorporated with bioactive molecules, metallic nanoparticles, or other functional components to further enhance the osteogenic properties and accelerate the healing process. In this review, we summarize the recent developments in biomaterial science and the modification strategies applied to dental implants to inhibit biofilm formation and facilitate bone-implant integration. Furthermore, we summarized the obstacles existing in the process of laboratory research to reach the clinic products, and propose corresponding directions for future developments and research perspectives, so that to provide insights into the rational design and construction of dental implants with the aim to balance antibacterial efficacy, biological safety, and osteogenic property.

Zeolite imidazolate framework-8 in bone regeneration: A systematic review.

Zeolite imidazolate framework-8 (ZIF-8) is a biomaterial that has been increasingly studied in recent years. It has several applications such as bone regeneration, promotion of angiogenesis, drug loading, and antibacterial activity, and exerts multiple effects to deal with various problems in the process of bone regeneration. This systematic review aims to provide an overview of the applications and effectiveness of ZIF-8 in bone regeneration. A search of papers published in the PubMed, Web of Science, Embase, and Cochrane Library databases revealed 532 relevant studies. Title, abstract, and full-text screening resulted in 39 papers being included in the review, including 39 in vitro and 22 animal studies. Appropriate concentrations of nano ZIF-8 can promote cell proliferation and osteogenic differentiation by releasing Zn2+ and entering the cell, whereas high doses of ZIF-8 are cytotoxic and inhibit osteogenic differentiation. In addition, five studies confirmed that ZIF-8 exhibits good vasogenic activity. In all in vivo experiments, nano ZIF-8 promoted bone formation. These results indicate that, at appropriate concentrations, materials containing ZIF-8 promote bone regeneration more than materials without ZIF-8, and with characteristics such as promoting angiogenesis, drug loading, and antibacterial activity, it is expected to show promising applications in the field of bone regeneration. STATEMENT OF SIGNIFICANCE: This manuscript reviewed the use of ZIF-8 in bone regeneration, clarified the biocompatibility and effectiveness in promoting bone regeneration of ZIF-8 materials, and discussed the possible mechanisms and factors affecting its promotion of bone regeneration. Overall, this study provides a better understanding of the latest advances in the field of bone regeneration of ZIF-8, serves as a design guide, and contributes to the design of future experimental studies.

Photorenewable Azobenzene Polymer Brush-Modified Nanoadsorbent for Selective Adsorption of LDL in Serum.

The elevated concentration of low-density lipoprotein (LDL) is recognized as a leading factor of hyperlipidemia (HLP), and selective adsorption of serum LDL is regarded as a practical therapy. Based on the superior structure-function characteristics of stimuli-responsive materials, a photorenewable nanoadsorbent (SiO2@Azo@Gly) with high selectivity and reusability was developed using azobenzene as the functional ligand. Its principle was certified by the preparation of silicon nanoparticles with atom transfer radical polymerization (ATRP)-initiating groups via a sol-gel reaction and their subsequent grafting of azobenzene polymer brushes by surface-initiated ATRP, followed by modification with glycine. Immobilization of carboxylated azobenzene polymer brushes onto the nanoparticles endowed SiO2@Azo@Gly with high adsorption selectivity and reusability. The advanced nanoadsorbent exhibited excellent LDL adsorption capacity at about 27 mg/g and could be regenerated by illumination with high efficiency (circulations ≥ 5); this was further verified by transmission electron microscopy (TEM) and Fourier-transform infrared (FTIR) analysis. SiO2@Azo@Gly also demonstrated superior adsorption efficiency and selectivity in serum from HLP patients, the respective adsorption capacities of LDL, triglyceride, and total cholesterol were about 15.65, 24.48, and 28.36 mg/g, and the adsorption to high-density lipoprotein (cardioprotective effect) was only about 3.66 mg/g. Green regeneration of the nanoadsorbent could be achieved completely through a simple photoregeneration process, and the recovery rate was still 97.9% after five regeneration experiments.

Amphiphilic shell nanomagnetic adsorbents for selective and highly efficient capture of low-density lipoprotein from hyperlipidaemia serum.

Removal of low-density lipoprotein (LDL) from hyperlipemia patients' blood represents an effective approach to prevent the progression of atherosclerotic cardiovascular disease. Based on the LDL structural characteristics and intermolecular interactions, a tailored nano-adsorbent (Fe3O4@SiO2@PAA-PE) was prepared aimed at the removal of LDL from hyperlipemia serum with high selectivity. The core-shell structured magnetic nanoparticles were embedded in an amphiphilic layer composed of hydrophilic poly(acrylic acid) and lipophilic phospholipids to provide multifunctional binding for LDL particles. The results of dynamic light scattering, water contact angle and zeta-potential measurements, thermal gravimetric analysis, and X-ray photoelectron spectroscopy together with Fourier transform infrared spectroscopy confirmed the core-shell structured nanoparticles bearing amphiphilic poly acrylic acid and phospholipid molecules. Because of the superior electronegativity of the functional layer, the nano-adsorbent demonstrated favorable adsorption selectivity against high-density lipoprotein, which possesses a similar structure to LDL but has a cardio-protective function in the human body. The respective adsorption capacity of Fe3O4@SiO2@PAA-PE towards LDL, total cholesterol and triglycerides reached up to 6.26 mg g-1, 8.41 mg g-1 and 9.19 mg g-1, which was 7.03, 9.45 and 10.32 times that towards HDL (0.89 mg g-1). The kinetic and isothermal studies revealed that multiple interactions containing both physical and chemical adsorption occurred in the binding procedure between LDL and Fe3O4@SiO2@PAA-PE, and chemical adsorption may play a more predominant role in LDL adsorption. The nano-adsorbent also had negligible effects on blood cells, and possessed satisfactory recyclability, low cytotoxicity and hemolysis ratios, indicating its good application prospects as a hemoperfusion adsorbent in the treatment of hyperlipidaemia.

Protein corona-coated immunomagnetic nanoparticles with enhanced isolation of circulating tumor cells.

Immunomagnetic nanoparticles (IMNs) have been widely developed as a detection tool to isolate rare circulating tumor cells (CTCs) from whole blood as a potential method for early cancer diagnosis, metastasis examination, and treatment guidance. However, a spontaneous interaction between nanoparticles and proteins results in the formation of a protein corona that reduces the performance of IMNs when they enter body fluids. To address this issue, the protein corona was precoated onto magnetic nanoparticles (C-MNs), and then their surfaces were conjugated with an immuno-antibody. The adsorption of proteins on C-MNs was decreased 6-fold and non-specific cell binding was reduced 5-fold, compared with magnetic nanoparticles (MNs). Furthermore, the immuno-antibody functionalized C-MNs (IC-MNs) maintained highly specific CTC capture performance when exposed to blood plasma. By using artificial spiked blood samples, IC-MNs exhibited 90.2% CTC isolation efficiency, compared with 60.3% by using IMNs. IC-MNs also successfully captured CTCs with high purity in 24 out of 26 female breast cancer patient blood samples. This work demonstrated that a novel preformed protein corona strategy can provide a useful clinically applicable diagnostic tool.

Biomembrane-mimetic hemoperfusion adsorbent for efficient removal of low-density lipoprotein from hyperlipemia blood.

Lowering of low-density lipoprotein (LDL) levels in blood of patients with hyperlipidaemia can effectively prevent the progression of atherosclerosis and coronary heart disease. The present study demonstrated a facile synthesis strategy to prepare biomembrane-mimetic LDL adsorbent (PVA@COOH-PE) via directional immobilization of phospholipid onto macro-porous cross-linked poly(vinyl alcohol) spheres. The binding between the prepared adsorbent and LDL particles simulates the cytosolic lipid droplets to form a lipid-packing structure. The adsorbent possesses satisfactory removal efficiency for LDL and total cholesterol (TCH) in hyperlipemia serum, while remains high-density lipoprotein (HDL) concentration within the normal range. The adsorption capacities for LDL and TCH are about 1.13 and 1.74 mg/ml respectively, which are nearly three and four times higher than that of HDL (0.42 mg/ml). The adsorbent also possesses satisfactory anticoagulant properties, causes negligible effect on blood cells and produces low hemolysis ratios. The excellent blood compatibility plus LDL removal efficiency of PVA@COOH-PE indicates its good application prospect as hemoperfusion adsorbent in the treatment of hyperlipidaemia.

The development of immunosorbents for the treatment of systemic lupus erythematosus via hemoperfusion.

Systemic lupus erythematosus (SLE) is an autoimmune disease (AID) that involves multiple organ systems and is characterized by elevated levels of autoantibodies (ANA) and immune complexes. The immunoadsorption technique uses an extracorporeal clearance process to remove pathogenic toxins from patients' blood and alleviate disease symptoms. An immunosorbent is a key component of the immunoadsorption system that determines therapeutic efficacy and safety. Immunosorbents are prepared by immobilizing antibodies, antigens, or ligands with specific physicochemical affinities on a supporting matrix. Immunosorbents and pathogenic toxins bind via affinity adsorption, which involves electrostatic interactions, hydrogen bonds, hydrophobic interactions, and van der Waals forces. Immunosorbents are classified on the basis of their interaction mechanism with toxins into three categories: non-selective, semi-selective, and highly selective. This review aimed to summarize the current status of various commercial immunosorbents that are used to treat SLE. Moreover, recent developments in immunosorbents have heightened the need for a brief discussion about specific ligands and a supporting matrix.

Bio-inspired dual-functional phospholipid-poly(acrylic acid) brushes grafted porous poly(vinyl alcohol) beads for selective adsorption of low-density lipoprotein.

Elevated levels of low-density lipoproteins (LDL) are recognized as a crucial indicator of hyperlipidemia (HLP) and lowering of LDL levels represents an effective clinical treatment strategy. Inspired by the conjugation of phospholipid monolayers and the lipid content of the LDL particle, the current study describes the preparation of an innovative hemoperfusion adsorbent. The adsorbent was prepared by attachment of phosphatidyl ethanolamine to poly(acrylic acid) modified poly(vinyl alcohol-co-triallyl isocyanurate) beads (PVA@PAA-PE). The interaction between LDL and adsorbent mimics the lipoprotein microemulsion present in the blood and thus promotes efficient binding with high affinity. In vitro adsorption using serum from patients with HLP revealed that the LDL adsorption of PVA@PAA-PE was 4.44 times higher than that of controls and the removal rate of LDL using PVA@PAA-PE was about twice as high as that of the anti-atherogenic high-density lipoprotein (HDL). In vivo whole blood perfusion demonstrated the superior affinity of PVA@PAA-PE for LDL since LDL concentration was significantly reduced from 10.71 ± 2.36 mmol L-1 to 6.21 ± 1.45 mmol L-1, while the HDL level was not severely reduced (from 0.98 ± 0.12 mmol L-1 to 0.56 ± 0.15 mmol L-1). Additionally, PVA@PAA-PE exhibited excellent hemocompatibility and low cytotoxicity. Therefore, PVA@PAA-PE is a potential adsorbent for whole blood perfusion to treat hyperlipidemia.

Hydroxyapatite reinforced inorganic-organic hybrid nanocomposite as high-performance adsorbents for bilirubin removal in vitro and in pig models.

Highly efficient removal of bilirubin from whole blood directly by hemoperfusion for liver failure therapy remains a challenge in the clinical field due to the low adsorption capacity, poor mechanical strength and low biocompatibility of adsorbents. In this work, a new class of nanocomposite adsorbents was constructed through an inorganic-organic co-crosslinked nanocomposite network between vinyltriethoxysilane (VTES)-functionalized hydroxyapatite nanoparticles (V-Hap) and non-ionic styrene-divinylbenzene (PS-DVB) resins (PS-DVB/V-Hap) using suspension polymerization. Notably, our adsorbent demonstrated substantially improved mechanical performance compared to the pure polymer, with the hardness and modulus increasing by nearly 3 and 2.5 times, respectively. Moreover, due to the development of a mesoporous structure, the prepared PS-DVB/V-Hap3 exhibited an ideal adsorption capacity of 40.27 mg g-1. More importantly, the obtained adsorbent beads showed outstanding blood compatibility and biocompatibility. Furthermore, in vivo extracorporeal hemoperfusion verified the efficacy and biosafety of the adsorbent for directly removing bilirubin from whole blood in pig models, and this material could potentially prevent liver damage and improve clinical outcomes. Taken together, the results suggest that PS-DVB/V-Hap3 beads can be used in commercial adsorption columns to threat hyperbilirubinemia patients through hemoperfusion, thus replacing the existing techniques where plasma separation is initially required.

Targeting regulation of the tumour microenvironment induces apoptosis of breast cancer cells by an affinity hemoperfusion adsorbent.

The cytokine network of tumour microenvironment (TME) plays an important role in cancer growth and progression. The current work aims to provide a new strategy for cancer therapy based on the targeted regulation of cytokines in the TME. Here, heparin-coupled polyvinyl alcohol (PVA-H) microspheres have been developed as an adsorbent for selectively remove tumour-induced immunosuppressive cytokines, such as vascular endothelial growth factor (VEGF) and transforming growth factor-beta (TGF-ß), but not tumour necrosis factor-alpha (TNF-α) which has an immune-stimulating effect and can inhibit tumour growth. The proliferation and apoptosis of breast cancer cells after perfusion were tested by cell viability assays, flow cytometry analysis and mRNA microarray assays. Results showed that the PVA-H microspheres efficiently absorbed the majority of VEGF (74.39%) and TGF-ß (86.39%), but much less TNF-α (4.16%). The regulation of the cytokines had remarkable anti-proliferative and pro-apoptotic effects on breast cancer cells, which was further confirmed from the change of mRNA expression levels. Thus, targeting regulatory pathways within the TME by an affinity adsorbent that selectively depletes immunosuppressive cytokines is potentially a new and promising strategy for cancer therapy.

A novel heterologous expression strategy for the quorum-quenching enzyme MomL in Lysobacter enzymogenes to the inhibit pathogenicity of Pectobacterium.

Quorum-quenching (QQ) enzymes can block the quorum-sensing (QS) system and prevent the expression of QS-controlled pathogenic factors in bacteria. However, the low expression levels of QQ proteins in the original host bacteria have affected their widespread application. In this study, we heterologously expressed momL, encoding a QQ enzyme with high activity, in Lysobacter enzymogenes. A "yellow-to-white" selection marker and the high-constitutive-expression promoter PgroEL were used in this novel heterologous expression system. In addition, we optimized the spacer between the SD sequence and the initiator to improve the efficiency of the expression system by 1.54-fold. The engineered strain LeMomL degraded the AHL molecule and the virulence factors of Pectobacterium carotovorum subsp. carotovora (Pcc). Additionally, LeMomL significantly decreased the disease caused by Pcc in Chinese cabbages and carrot root tissues. In conclusion, this novel and facile L. enzymogenes expression strategy has good prospects and is an ideal approach for foreign protein expression.

Interspecies and Intraspecies Signals Synergistically Regulate Lysobacter enzymogenes Twitching Motility.

The twitching motility of bacteria is closely related to environmental adaptability and pathogenic behaviors. Lysobacter is a good genus in which to study twitching motility because of the complex social activities and distinct movement patterns of its members. Regardless, the mechanism that induces twitching motility is largely unknown. In this study, we found that the interspecies signal indole caused Lysobacter to have irregular, random twitching motility with significantly enhanced speed. Deletion of qseC or qseB from the two-component system for indole signaling perception resulted in the disappearance of rapid, random movements and significantly decreased twitching activity. Indole-induced, rapid, random twitching was achieved through upregulation of expression of gene cluster pilE1-pilY11-pilX1-pilW1-pilV1-fimT1 In addition, under conditions of extremely low bacterial density, individual Lysobacter cells grew and divided in a stable manner in situ without any movement. The intraspecies quorum-sensing signaling factor 13-methyltetradecanoic acid, designated L. enzymogenes diffusible signaling factor (LeDSF), was essential for Lysobacter to produce twitching motility through indirect regulation of gene clusters pilM-pilN-pilO-pilP-pilQ and pilS1-pilR-pilA-pilB-pilC These results demonstrate that the motility of Lysobacter is induced and regulated by indole and LeDSF, which reveals a novel theory for future studies of the mechanisms of bacterial twitching activities.IMPORTANCE The mechanism underlying bacterial twitching motility is an important research area because it is closely related to social and pathogenic behaviors. The mechanism mediating cell-to-cell perception of twitching motility is largely unknown. Using Lysobacter as a model, we found in this study that the interspecies signal indole caused Lysobacter to exhibit irregular, random twitching motility via activation of gene cluster pilE1-pilY11-pilX1-pilW1-pilV1-fimT1 In addition, population-dependent behavior induced by 13-methyltetradecanoic acid, a quorum-sensing signaling molecule designated LeDSF, was involved in twitching motility by indirectly regulating gene clusters pilM-pilN-pilO-pilP-pilQ and pilS1-pilR-pilA-pilB-pilC The results demonstrate that the twitching motility of Lysobacter is regulated by these two signaling molecules, offering novel clues for exploring the mechanisms of twitching motility and population-dependent behaviors of bacteria.

Indole-Induced Reversion of Intrinsic Multiantibiotic Resistance in Lysobacter enzymogenes.

Lysobacter species are a group of environmental bacteria that are emerging as a new source of antibiotics. One characteristic of Lysobacter is intrinsic resistance to multiple antibiotics, which had not been studied. To understand the resistance mechanism, we tested the effect of blocking two-component regulatory systems (TCSs) on the antibiotic resistance of Lysobacter enzymogenes, a prolific producer of antibiotics. Upon treatment with LED209, an inhibitor of the widespread TCS QseC/QseB, L. enzymogenes produced a large amount of an unknown metabolite that was barely detectable in the untreated culture. Subsequent structural elucidation by nuclear magnetic resonance (NMR) unexpectedly revealed that the metabolite was indole. Indole production was also markedly induced by adrenaline, a known modulator of QseC/QseB. Next, we identified two TCS genes, L. enzymogenesqseC (Le-qseC) and Le-qseB, in L. enzymogenes and found that mutations of Le-qseC and Le-qseB also led to a dramatic increase in indole production. We then chemically synthesized a fluorescent indole probe that could label the cells. While the Le-qseB (cytoplasmic response regulator) mutant was clearly labeled by the probe, the Le-qseC (membrane sensor) mutant was not labeled. It was reported previously that indole can enhance antibiotic resistance in bacteria. Therefore, we tested if the dramatic increase in the level of indole production in L. enzymogenes upon blocking of Le-qseC and Le-qseB would lead to enhanced antibiotic resistance. Surprisingly, we found that indole caused the intrinsically multiantibiotic-resistant bacterium L. enzymogenes to become susceptible. Point mutations at conserved amino acids in Le-QseC also led to antibiotic susceptibility. Because indole is known as an interspecies signal, these findings may have implications.IMPORTANCE The environmental bacterium Lysobacter is a new source of antibiotic compounds and exhibits intrinsic antibiotic resistance. Here, we found that the inactivation of a two-component regulatory system (TCS) by an inhibitor or by gene deletion led to a remarkable increase in the level of production of a metabolite in L. enzymogenes, and this metabolite was identified to be indole. We chemically synthesized a fluorescent indole probe and found that it could label the wild type and a mutant of the TCS cytoplasmic response regulator but not a mutant of the TCS membrane sensor. Indole treatment caused the intrinsically multidrug-resistant bacterium L. enzymogenes to be susceptible to antibiotics. Mutations of the TCS sensor also led to antibiotic susceptibility. Because indole is known as an interspecies signal between gut microbiota and mammalian hosts, the observation that indole could render intrinsically resistant L. enzymogenes susceptible to common antibiotics may have implications.