Effects of different frequencies of Er:YAG laser on the bonding properties of zirconia ceramic.

The effects of Er:YAG laser with different frequencies on zirconia ceramic's bonding properties were studied. In total, 42 Y-TZP (yttrium-stabilized tetragonal zirconia polycrystals, UPCERA ST) with 3 mm × 3 mm × 2 mm divided into 6 groups (n = 7): control (C), sandblasting (SB), and Er:YAG laser (A1-A4), which the frequencies correspond to 5 Hz, 10 Hz, 15 Hz, and 20 Hz, IPS e.max Press ceramics were B. Scanning electron microscope (SEM) images were recorded. The ceramics were bonded to enamel from extracted teeth. After being constantly stored at 37 ℃ for 24 h, the shear test was performed with a universal testing machine. Stereomicroscope evaluated fracture modes. Stereomicroscope evaluated fracture modes. Data were analyzed by SPSS26.0 statistical software; the standard was P = 0.05. (1) The SEM showed the surface of A1-A4 became rough compared with C. (2) The shear test showed that the highest bonding strength for B was 13.15 ± 2.97 MPa, followed by SB was 7.78 ± 0.97 MPa, and A2 was 7.13 ± 0.75 MPa. However, there was no significant difference between SB and A2 (P > 0.05). Fracture modes of C were the interface fracture of Y-TZP and resin adhesive; most of A1-A4 and SB also were interface fracture, a few mixed fractures, and cohesion fracture of resin adhesive; B were all mixed fracture. Er:YAG laser with 10 Hz could be used as an alternative to sandblasting with Al2O3 for surface modification of Y-TZP to increase the bonding strength.

Effects of polystyrene microplastics on the metabolic level of Pseudomonas aeruginosa.

Given the widespread presence of Pseudomonas aeruginosa in water and its threat to human health, the metabolic changes in Pseudomonas aeruginosa when exposed to polystyrene microplastics (PS-MPs) exposure were studied, focusing on molecular level. Through non-targeted metabolomics, a total of 64 differential metabolites were screened out under positive ion mode and 44 under negative ion mode. The content of bacterial metabolites changed significantly, primarily involving lipids, nucleotides, amino acids, and organic acids. Heightened intracellular oxidative damage led to a decrease in lipid molecules and nucleotide-related metabolites. The down-regulation of amino acid metabolites, such as L-Glutamic and L-Proline, highlighted disruptions in cellular energy metabolism and the impaired ability to synthesize proteins as a defense against oxidation. The impact of PS-MPs on organic acid metabolism was evident in the inhibition of pyruvate and citrate, thereby disrupting the cells' normal participation in energy cycles. The integration of Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that PS-MPs mainly caused changes in metabolic pathways, including ABC transporters, Aminoacyl-tRNA biosynthesis, Purine metabolism, Glycerophospholipid metabolism and TCA cycle in Pseudomonas aeruginosa. Most of the differential metabolites enriched in these pathways were down-regulated, demonstrating that PS-MPs hindered the expression of metabolic pathways, ultimately impairing the ability of cells to synthesize proteins, DNA, and RNA. This disruption affected cell proliferation and information transduction, thus hampering energy circulation and inhibiting cell growth. Findings of this study supplemented the toxic effects of microplastics and the defense mechanisms of microorganisms, in turn safeguarding drinking water safety and human health.

Synergistic influence of diatomite and MoS2 nanosheets on the self-alkali-activated cementation of the municipal solid waste incineration fly ash and mechanisms.

The solidification/stabilization technique recommended for the disposal of municipal solid waste incineration (MSWI) fly ashes in developed countries was inappropriate for the treatment in most developing counterparts. In this study, the diatomite and MoS2 nanosheets were synergistically employed to activate the self-alkali-activated cementation of the MSWI fly ashes to achieve efficient solidification, the immobilization of heavy metals (HMs), and the inhibition of chloride release. The compressive strength of 28.61 MPa and the leaching toxicities (mg/L) of Zn, Pb, Cu, Cd, and Cr of 2.26, 0.87, 0.5, 0.06, and 0.22 were obtained from the hardened mortars. Diatomite significantly influenced the self-alkali-activated cementation of the MSWI fly ashes while MoS2 nanosheets played both roles in intensifying the stabilization of HMs and strengthening the binding process by inducing the formation of sodalite and kaolinite, enhancing the growth rates of nucleation, and transforming the layered cementation to the partial and full three-dimensional cementation in the hardened matrix. This study not only verified the feasibility of diatomite and MoS2 in activating the self-alkali-activated cementation of the MSWI fly ashes but also supplied a reliable technique for the harmless disposal and efficient utilization of MSWI fly ashes in developing countries.

[Influence of Polystyrene Microplastics on the Formation and Structural Change of Pseudomonas aeruginosa Biofilm].

Microplastic pollution in the water environment is becoming increasingly serious, impacting the growth and development of aquatic organisms. There are limited studies on the mechanisms of microplastic effects on biofilm formation. Therefore, in this study, the effects of polystyrene microplastics (PS-MPs) were investigated on the biofilm formation and development of Pseudomonas aeruginosa. Different concentrations and particle sizes of PS-MPs were selected for exposure tests to explore the effects on biofilm biomass, oxidative stress levels, biofilm structure, and population sensing system. The results showed that PS-MPs induced severe oxidative stress and inhibited biofilm formation and development, and the smaller the particle size, the stronger the inhibitory effect was. The inhibition effect was 0.1 µm>0.5 µm≈1 µm>5 µm. PS-MPs caused severe physical damage through contact with bacteria. The thickness of the biofilm was significantly reduced, damaging the structural stability. The bacteria in the biofilm secreted extracellular polymers to resist the stress of PS-MPs. Meanwhile, PS-MPs interfered with the QS system of P. aeruginosa; down-regulated the expression levels of key genes lasI, lasR, rhlI, and rhlR; inhibited the synthesis and secretion of signal molecules and related virulence factors; and ultimately affected the formation and structural stability of biofilms.

[Influence of Microplastics on the Development of Proteus Biofilm].

Currently, research on the effects of microplastics (MPs) in biofilms has mainly been focused on the mature biofilm communities, with a lack of sufficient details on the influence on different development stages of biofilms. Proteus and 1 µm polystyrene microplastics (PS-MPs), which are widely found in the environment, were selected as the research objects to explore the effects of microplastics on biofilms at different developmental stages. In our study, the effects of PS-MPs on biofilm biomass, extracellular polymer composition(EPS), and extracellular enzyme activity were investigated using an exposure test. Our results showed that the effect of PS-MPs on biofilms at different stages was similar, but the effect was significantly reduced with the development of biofilms. Biofilms at different development stages had different sensitivities to microplastics. In the reversible attachment stage, the no observed effect concentration (NOEC) of EPS composition, reactive oxygen species (ROS) production, and extracellular enzyme activity were significantly lower than those in other stages; however, the NOEC of total antioxidant capacity (T-AOC) and lactate dehydrogenase (LDH) activity were similar. This may be the result of ROS-mediated protein oxidation, which can be reduced but not completely eliminated by EPS in other stages of biofilm. This indicates that PS-MPs has a low toxic effect on biofilm.

Coagulation combined with ultraviolet irradiation activated sodium percarbonate as pretreatment prior to ultrafiltration: Analysis of free radical oxidation mechanism and membrane fouling control.

Novel pre-coagulation-sedimentation integrated with ultraviolet activated sodium percarbonate (SPC) (Fe(III)-UV/SPC) processes are promising methods for ultrafiltration (UF) pretreatment to ensure the safety of rural drinking water and mitigate UF membrane fouling. The process of surface water purification using the integrated coagulation-advanced oxidation processes (AOPs)-UF system relies on the idea that pre-coagulation can remove hydrophobic macromolecular organic compounds, thus facilitating the oxidation of hydrophilic molecules or medium-sized macromolecules to improve the utilization efficiency of free radicals in AOPs. Compared with the UV/SPC process, the removal rates of UV254 and DOC in the Fe(III)-UV/SPC process (Fe(III) = 0.1 mM, SPC = 0.5 mM) were increased from 87.39 % to 41.45 %-93.56 % and 52.51 %, respectively. Furthermore, the dosage of SPC was reduced from 0.75 mM in UV/SPC process to 0.5 mM due to effects of pre-coagulation. The free radical quenching experiment showed that a significant radical sink of reactions with organic contaminants was formed by •OH and CO3•- in the UV/SPC process, rather than a single specific radical. The destruction of the cake layer structure, reduction in contaminant concentration, and appearance of many permeable holes on the membrane surface were the main reasons for the alleviation of UF membrane fouling. Finally, the trans-membrane pressure and reversible membrane resistance decreased from 22.33 kPa to 3.68 × 1011 m-1 to 18.28 kPa and 0.93 × 1011 m-1, respectively. These results provide new insights into the behavior of membrane fouling control and offer technical references for the long-term stable operation of the UF process.

A novel janus membrane modified by MXene for enhanced anti-fouling and anti-wetting in direct contact membrane distillation.

Membrane fouling and wetting limit the applications of membrane distillation (MD) for wastewater treatment, especially when treating the wastewater with a high concentration of low surface tension substances such as oil and surfactants. In this paper, virgin polyvinylidene fluoride (PVDF) membrane was modified by polydimethylsiloxane (PDMS) to enhance anti-wetting ability. Then a thin polydopamine (PDA) layer was coated as a reaction platform for further modification. Polyethyleneimine (PEI) was cross-linked with PDA to form a uniform and stable layer, through hydrogen bonds and electrostatic interaction to immobilize hydrophilic MXene, which formed a Janus MXene-PVDF membrane. The MXene layer was the key for superoleophobicity and high liquid entry pressure (LEP) of membrane, capable of mitigating membrane fouling and wetting when dealing with low surface tension wastewater (LSTW). From the experiments results, pristine PVDF membrane showed severe fouling and wetting with flux decline and salt leakage during treatment of LSTW (surfactants containing water, oil-in-water emulsion and sodium dodecyl sulfate stabilized oil-in-water emulsion). However, under the same conditions, the Janus MXene-PVDF membrane exhibited remarkably stable flux (9.3 kg m-2h-1, 9.1 kg m-2h-1, 10.2 kg m-2h-1) and salt rejection (almost 99.9%) after 15 h operation. Excellent fouling and wetting resistance of MXene-PVDF membrane was mainly attributed to its superhydrophilic and superoleophobic top surface (in-air water contact angle: 30.2°, under-water oil contact angle: 169.9°) and hydrophobic substrate (in-air water contact angle: 130.8°), together with high LEP value (91.1 Kpa). This study provides a viable route to fabricated a Janus membrane with outstanding fouling and wetting resistance for LSTW, oily wastewater and it has great potential for sewage treatment in the future.

Deposition of polystyrene microplastics on bare or biofilm-coated silica analysed via QCM-D.

The mobility of microplastics (MPs) in aqueous media is closely related to their environmental risk. The naturally occurring silica substrate surface in the aquatic environment is easily colonized by microorganisms and forms a biofilm, which may affect the migration and distribution of MPs. Herein, a typical MP, polystyrene (PS), and Pseudomonas fluorescens (P. fluorescens) biofilms were selected to study the deposition and release of pristine or ultraviolet (UV)-aged PS MPs on silica and biofilms under different ionic strengths using a quartz crystal microbalance dissipation (QCM-D) system. Statistical analyses of the deposition experiments revealed a significant impact of P. fluorescens biofilms on deposition (p = 0.0042). The deposition rate of weathered MPs on the biofilms was 4.0 ± 0.1 to 16.3 ± 0.6 times that on silica. A release experiment revealed that the biofilm reduced the release fraction (fr) of weathered MPs by 34.5 ± 0.3 % compared to bare silica. In addition, the UV-ageing treatment reduced the deposition mass of MPs on the surface of silica by 27.6 ± 0.21 % compared to pristine microspheres. The analysis of the deposition mechanism revealed that the promotion and inhibition of biofilm or UV-ageing treatment on the deposition of microspheres could be attributed to the non-Derjaguin-Landau-Verwey-Overbeek (DLVO) force and the decreased electrostatic repulsion or the increased hydration repulsion, respectively.

Ultrafiltration of up-flow biological activated carbon effluent: Extracellular polymer biofouling mechanism and mitigation using pre-ozonation with H2O2 backwashing.

Biofouling is a key problem in membrane filtration, and extracellular polymer substances (EPS) play a key role in biofouling. Biofouling contributes to membrane fouling during ultrafiltration of up-flow biological activated carbon filter (UBACF) effluent. EPS are released when pollutants get attached with membrane surface and when pollutants are in solution phase from cell lysis and by cell secretions. In our study of EPS + humic acid (HA) prepared as the effluent pollutants for ultrafiltration, we found that EPS increased the interfacial forces between the pollutants and the membrane, resulting in membrane fouling. In the early stages of filtration, the main contribution of EPS to membrane fouling was to bond with organic colloids, which led to an increase in the pollutant particle size and zeta potential. This increased the short-range Lewis acid-base (AB) forces from -4.89 nN to -12.59 nN and accelerated the formation of a cake layer. In the late stage of filtration, the EPS increased both the AB and London-van der Waals (LW) forces, thus accelerating membrane fouling. In order to mitigate biofouling, we developed a method of pretreating the effluent with 0.4 mg/L ozone prior to ultrafiltration and backwashing with 8 mg/L H2O2 to sterilize bacteria attached to the membrane surface. This method not only changed the characteristics of the EPS, but also inactivated bacteria by disinfection with H2O2, thereby reducing the amount of EPS. The proposed method provided a long-term stable operation guarantee for ultrafiltration of UBACF effluent.

Control of ultrafiltration membrane fouling during the recycling of sludge water based on Fe(II)-activated peroxymonosulfate pretreatment.

Sludge water was recycled using an ultrafiltration (UF) system. In order to control membrane fouling, three typical Fe(II)-activated peroxymonosulfate (PMS) processes: Fe(II)/PMS-UF (FPUF), 1/4Fe(II) × 4/PMS-UF (F4PUF) (adding Fe(II) in small increments four times), and Fe(II)/thiosulfate/PMS-UF (FTPUF) (adding Fe(II) after complexing with thiosulfate), were employed as UF pretreatments. Their mitigating effects of UF membrane fouling caused by sludge water are systematically discussed and compared. The results showed that FTPUF system had the best membrane fouling control effect. The F4PUF system was more suitable for long-term operation than FPUF due to its lower irreversible resistance. The pretreatments can effectively remove contaminants from sludge water through the dual effects of coagulation and oxidation. Specifically, coagulation removed most of the particles and macromolecular organic matter. Oxidation effectively decomposed fluorescent and UV-absorbing organic components, and reduced bacterial proliferation on the membrane surface. Concentrations of 2-methylisoborneol and geosmin in FPUF permeate were dramatically increased, which was mainly due to the rupture of algal cells in sludge water. Both adhesion force date and extended Derjaguin-Landau-Verwey-Overbeek theory indicated that the pretreatments significantly reduced interactions between the membrane-organic colloid and cake layer-organic colloid. In contrast, the stronger membrane-organic colloid interaction was a major contributor to membrane fouling. The mitigation of irreversible fouling was mainly attributed to the fact that oxidation enhanced the hydrophilicity of the organic colloids, thereby reducing the Lewis acid-base interaction energy. The results demonstrated the potential application of different Fe(II)-activated PMS processes as pretreatments for membrane fouling control during sludge water treatment.

A self-illuminating nanoparticle for inflammation imaging and cancer therapy.

Nanoparticles have been extensively used for inflammation imaging and photodynamic therapy of cancer. However, the major translational barriers to most nanoparticle-based imaging and therapy applications are the limited depth of tissue penetration, inevitable requirement of external irradiation, and poor biocompatibility of the nanoparticles. To overcome these critical limitations, we synthesized a sensitive, specific, biodegradable luminescent nanoparticle that is self-assembled from an amphiphilic polymeric conjugate with a luminescent donor (luminol) and a fluorescent acceptor [chlorin e6 (Ce6)] for in vivo luminescence imaging and photodynamic therapy in deep tissues. Mechanistically, reactive oxygen species (ROS) and myeloperoxidase generated in inflammatory sites or the tumor microenvironment trigger bioluminescence resonance energy transfer and the production of singlet oxygen (1O2) from the nanoparticle, enabling in vivo imaging and cancer therapy, respectively. This self-illuminating nanoparticle shows an excellent in vivo imaging capability with suitable tissue penetration and resolution in diverse animal models of inflammation. It is also proven to be a selective, potent, and safe antitumor nanomedicine that specifically kills cancer cells via in situ 1O2 produced in the tumor microenvironment, which contains a high level of ROS.

Development of a nanoliposomal formulation of erlotinib for lung cancer and in vitro/in vivo antitumoral evaluation.

The aim of this study was to develop PEGylation liposomes formulations of erlotinib and evaluate their characteristics, stability, and release characteristics. The average particle sizes and entrapment efficiency of PEGylation erlotinib liposomes are 102.4±3.1 nm and 85.3%±1.8%, respectively. Transmission electron microscopy images showed that the liposomes dispersed well with a uniform shape and no changes during the storage. The in vitro drug-release kinetic model of erlotinib release from the PEGylation liposomes in phosphate-buffered saline fit well with the Higuchi equation. In vitro anticancer activity assay showed that the blank liposomes had lower cellular cytotoxicity and that the cellular cytotoxicity of erlotinib liposomes increased significantly under the same incubation condition, which should contribute to the increase in intracellular drug concentration by the transportation of liposomes. The two liposomes of erlotinib (with and without PEGylation) exhibited similar cellular cytotoxicity with no significantly different concentrations. Pharmacokinetic results indicated that erlotinib-loaded PEGylation liposomes can significantly change the pharmacokinetic behavior of drugs and improve the drug bioavailability by nearly 2 times compared to ordinary liposomes. No sign of damages such as the appearance of epithelial necrosis or sloughing of epithelial cells was detected in histological studies.

[PREPARATION AND BIOCOMPATIBILITY EVALUATION OF A FUNCTIONAL SELF-ASSEMBLING PEPTIDE NANOFIBER HYDROGEL DESIGNED WITH LINKING THE SHORT FUNCTIONAL MOTIF OF BONE MORPHOGENETIC PROTEIN 7].

OBJECTIVE: To prepare of a novel functional self-assembling peptide nanofiber hydrogel scaffold RADKPS designed with linking the short functional motif of bone morphogenetic protein 7 (BMP-7) and to evaluate its biocompatibiity so as to provide the experimental basis for in viva studies on regeneration of degenerated nucleus pulposus tissue. METHODS: A functional self assembling peptide RADA-KPSS was designed by linking the short functional motif of BMP-7 to the self assembling peptide RADA16-I. And the novel functional self assembling peptide RADKPS was finally prepared by isometric mixing RADA16-I with RADA-KPSS. The structure characteristic of the functional self-assembling peptide nanofiber hydrogel scaffold RADKPS was evaluated by general observation and atomic force microscopy. Bone marrow mesenchymal stem cells (BMSCs) were isolated from 3-month-old New Zealand white rabbits and cultured. After the 3rd generation BMSCs were seeded on the peptide nanofiber hydrogel scaffold RADKPS for 7 days, the cellular compatibility of RADKPS was evaluated through scanning electron microscopy assay, cellular fluorescein diacetate/propidium iodide staining, and MTT assay. 1%RADKPS was injected into isolated intervertebral disc organs from 6-month-old New Zealand white rabbits, then the organs were cultured and the cellular activity of the intervertebral disc organs was observed. The blood compatibility of RADKPS was evaluated with hemolytic assay. After RADKPS was implanted into subcutaneous part of Kunming mice (aged 6-8 weeks) for 28 days, general observation and HE staining were carried out to evaluate the tissue compatibility. RESULTS: The functional self-assembling peptide solution RADKPS presented a homogeneous transparent hydrogel-like. Atomic force microscopy revealed that the RADKPS could self-assemble into three-dimensional nanofiber hydrogel scaffolds; the fibre diameter was (25.68 ± 4.62) nm, and the fibre length was (512.42 ± 32.22) nm. After BMSCs cultured on RADKPS for 7 days, scanning electron microscopy showed that BMSCs adhered to the scaffolds. And cell viability was maintained over 90%. MTT assay revealed that RADKPS of 0.1%, 0.05%, and 0.025% could increase the proliferation of BMSCs. The result of hemolytic assay revealed that the hemolysis rates of the RADKPS solutions with different concentrations were less than 5%, indicating that it met the requirement of hemolytic assay standard for medical biomaterials. After subcutaneous implantation, no vesicle, erythema, and eschar formation around injection site were observed. Meanwhile, HE staining showed inflammatory cells infiltration (lymphocytes), substitution of hydrogel scaffold by fibrous tissue, and good tissue compatibility. CONCLUSION: The novel functional self-assembling peptide nanofiber hydrogel scaffold RADKPS has good biocompatibility and biological reliability, which would be suitable for tissue engineering repair and regeneration of nucleus pulposus tissue.

[The protective effects to the function of kidney and long by clearing of cytokines in patients with open-heart surgery].

OBJECTIVE: To observe the effect of cytokines absorption on renal and respiratory function in patients with open-heart surgery. METHODS: 30 patients undergoing valve replacement with cardiopulmonary bypass (CPB) were randomly divided into two groups. A sulfonated polyacrylonitrile hemofilter (AN69) that has been used to absorb cytokines was connected into the efferent limb of CPB in Group A (n = 15), and a cellulose triacetate hemofilter (CT 190G) instead of AN69 was used as controls (Group B, n = 15). The levels of plasma pro-inflammatory (TNF-alpha, IL-6, IL-8) anti-inflammatory cytokines (IL-10, IL-1ra), C-reactive protein (CRP) levels, and post-operation renal and respiratory function were compared between the two groups. Blood samples were analysed for TNF-alpha and IL-6 and IL-8 and C-reactive protein (CRP). The changes in renal, respiratory function were also observed. RESULTS: (1) At the end of CPB, TNF-alpha 10 ng/L +/- 3 ng/L and IL-6 115 ng/L +/- 22 ng/L levels in Group A were significantly lower than that in Group B 13 ng/L +/- 3 ng/L, 134 ng/L +/- 29 ng/L) respectively (P < 0.05 in all). There is no statistical differences in plasma IL-10 and IL-1ra levels between the two groups. (2) After 24 hours of CPB, the magnitude of increased body temperature, heart rate, white blood cell and plasma CRP in Group A [1.6 degrees C +/- 0.2 degrees C, 15/min +/- 4/min, (17 +/- 3) x 10(9)/L, 56 mg/L +/- 13 mg/L], were significantly lower than that in Group B [2.1 degrees C +/- 0.2 degrees C, 23/min +/- 6/min, (22 +/- 3) x 10(9)/L, 69 mg/L +/- 15 mg/L] respectively (P < 0.05 in all). (3) After 24 hours of CPB, the levels of 24h urinary protein excretion and urinary N-acetyl-beta-D-glucosaminidase (NAG) were significantly lower in Group A when compared to that in Controls (0.20 g/d +/- 0.08 g/d vs 0.30 g/d +/- 0.14 g/d, 28 U/L +/- 11 U/L vs 38 U/L +/- 13 U/L respectively), P < 0.05 in all. The level of creatinine clearance (Ccr) in Group A (68 +/- 7) ml.min(-1).1.73 m(-2) was significantly elevated than that in Group B (57 +/- 11) ml.min(-1).1.73 m(-2) (P < 0.05). (4) One hour after the end of CPB, the magnitude of increased plateau airway pressure (P(Plateau)) and peak airway pressure (P(Peak)) in Group A were significantly lower than that in Controls (P < 0.01 in all). The duration that need mechanical ventilation after operation in Group A (4.9 h +/- 0.6 h) was much shorter than that in Group B (5.8 h +/- 0.8 h, P < 0.05). CONCLUSIONS: Lowering the plasma levels of cytokines by extracorporeal absorption may attenuate systemic inflammatory response and protect lung and kidney function in patients with open-heart surgery.

BMP7-Based Functionalized Self-Assembling Peptides for Nucleus Pulposus Tissue Engineering.

Nucleus pulposus (NP) tissue engineering has been demonstrated to be a feasible therapeutic strategy for intervertebral disc regeneration. In this study, we constructed a novel injectable biomaterial by conjugating three different short peptides of BMP7 to the C-terminus of the self-assembling peptide RADA16-I, and we then mixed each of these conjugates with RADA16-I at equal volumes to obtain the novel functionalized peptides RAD-SNV, RAD-KPS, and RAD-KAI. The bioactivities of these functionalized peptides for human degenerated NP cells (hdNPCs) were evaluated in vitro, and the most ideal scaffold was chosen for assessment of its in vivo degradation and the tissue reactions to it. All of the functionalized peptides self-assembled to form hydrogel scaffolds with a nanofibrous structure under physiological conditions. Compared with the RADA16-I and RAD-KAI scaffolds, the RAD-SNV and RAD-KPS scaffolds possessed better bioactivities for hdNPCs, which were characterized by their enhanced proliferation, migration, and ECM (collagen II, aggrecan, and sox-9) secretion. RAD-KPS was chosen over RAD-SNV as the most ideal scaffold material due to the cells' higher rate of expression of aggrecan both at the gene and protein level after 28 days of coculture. Moreover, in vivo analysis demonstrated that subcutaneously injected RAD-KPS degraded in vivo without invoking intense inflammation. Therefore, RAD-KPS is an ideal candidate scaffold for NP tissue engineering and holds great potential for NP regeneration.

Biological evaluation of human degenerated nucleus pulposus cells in functionalized self-assembling peptide nanofiber hydrogel scaffold.

Nucleus pulposus (NP) tissue engineering has been proposed as a novel biological treatment for early-stage intervertebral disc degeneration. In this study, a novel functional self-assembling peptide PKP was first designed by linking the short functional motif of bone morphogenetic protein-7 (BMP7) to the C-terminal of RADA16-I, and another new functional self-assembling peptide was obtained by mixing RKP with RADA16-I. Then, the biocompatibilities and bioactivities of RKP and RAD-RKP for human degenerated nucleus pulposus cells (hNPCs) were studied in vitro. Atomic force microscopy and scanning electron microscopy (SEM) confirmed that both RKP and RAD-RKP could self-assemble into three-dimensional (3D) nanofiber hydrogel scaffolds in a culture medium at 37°C. After the hNPCs were cultured in 3D scaffolds, both RKP and RAD-RKP exhibited reliable attachment and extremely low cytotoxicities (<14%), which were verified by SEM and cytotoxity assays, respectively. Our results also showed that the functional-based scaffolds could increase the proliferation and migration of hNPCs after 7 days compared with culture plates and pure RADA16-I. Quantitative real-time polymerase chain reaction demonstrated that the expressions of collagen II α1, Sox-9, and aggrecan were upregulated, while collagen I α1 was downregulated by functional-based scaffolds after 28 days. Furthermore, we also confirmed that RAD-RKP exhibited a higher hNPC proliferation, migration, and expression of Sox-9 and aggrecan compared with pure RKP. Therefore, the results of this study indicated that the BMP7 short motif-designed functional self-assembling peptide nanofiber hydrogels could be used as excellent scaffolds in NP tissue engineering, and RAD-RKP might have further potential application in human mild degenerated NP tissue regeneration.