Acid Nanocomposites Research Articles

Biocompatibility Assessment of Polylactic Acid (PLA) and Nanobioglass (n-BG) Nanocomposites for Biomedical Applications.

Scaffolds based on biopolymers and nanomaterials with appropriate mechanical properties and high biocompatibility are desirable in tissue engineering. Therefore, polylactic acid (PLA) nanocomposites were prepared with ceramic nanobioglass (PLA/n-BGs) at 5 and 10 wt.%. Bioglass nanoparticles (n-BGs) were prepared using a sol–gel methodology with a size of ca. 24.87 ± 6.26 nm. In addition, they showed the ability to inhibit bacteria such as Escherichia coli (ATCC 11775), Vibrio parahaemolyticus (ATCC 17802), Staphylococcus aureus subsp. aureus (ATCC 55804), and Bacillus cereus (ATCC 13061) at concentrations of 20 w/v%. The analysis of the nanocomposite microstructures exhibited a heterogeneous sponge-like morphology. The mechanical properties showed that the addition of 5 wt.% n-BG increased the elastic modulus of PLA by ca. 91.3% (from 1.49 ± 0.44 to 2.85 ± 0.99 MPa) and influenced the resorption capacity, as shown by histological analyses in biomodels. The incorporation of n-BGs decreased the PLA crystallinity (from 7.1% to 4.98%) and increased the glass transition temperature (Tg) from 53 °C to 63 °C. In addition, the n-BGs increased the thermal stability due to the nanoparticle’s intercalation between the polymeric chains and the reduction in their movement. The histological implantation of the nanocomposites and the cell viability with HeLa cells higher than 80% demonstrated their biocompatibility character with a greater resorption capacity than PLA. These results show the potential of PLA/n-BGs nanocomposites for biomedical applications, especially for long healing processes such as bone tissue repair and avoiding microbial contamination.

Heteropoly acid nanocomposite for disinfection and dye removal of licorice wastewater: fabrication of a novel fixed-bed photocatalytic reactor

Heteropoly acid nanocomposite for disinfection and dye removal of licorice wastewater: fabrication of a novel fixed-bed photocatalytic reactor

Polylactic acid nanocomposites containing functionalized multiwalled carbon nanotubes as antimicrobial packaging materials

Intended for food packaging, nanocomposites films based on poly (lactic acid) reinforced by polydopamine-wrapped carbon nanotubes (PLA/PDA-MWCNTs) or TiO2 modified PDA-MWCNTs (PLA/TiO2-PDA-MWCNTs) as nanofillers were elaborated via melt-blending and characterized by several techniques. The success of the synthesis of the modified MWCNTs was confirmed by transmission electron microscopy, Raman and Fourier transform infrared spectroscopies and thermogravimetric analysis. Properties such as slow crystallization rate, barrier, mechanical, antibacterial and antifungal properties, required for food packaging, have been investigated. As compared to a PLA pristine film, the PLA based modified MWCNTs at 3 wt% loading exhibited better properties, particularly the PLA/TiO2-PDA-MWCNTs nanocomposite film. Indeed, the crystallization rate increased about 10% for PLA/TiO2-PDA-MWCNTs and 7% for PLA/PDA-MWCNTs compared to the neat PLA. Besides, these improved results have positively impacted on the nanomechanical and barrier properties of PLA nanocomposites films. The Young modulus was increased by 161% for PLA/TiO2-PDA-MWCNTs and 113% for PLA/PDA-MWCNTs and the hardness was improved by 815% for PLA/TiO2-PDA-MWCNTs and 79% for PLA/PDA-MWCNTs, respectively, as compared to the pristine PLA. Furthermore, PLA based modified MWCNTs nanocomposite films displayed a strong antimicrobial and antifungal activity compared to pure PLA.

Acetone Gas Sensor Based on SWCNT/Polypyrrole/Phenyllactic Acid Nanocomposite with High Sensitivity and Humidity Stability.

We synthesized core-shell-shaped nanocomposites composed of a single-walled carbon nanotube (SWCNT) and heptadecafluorooctanesulfonic acid-doped polypyrrole (C8F-doped-PPy)/phenyllatic acid (PLA), i.e., C8F-doped-PPy/PLA@SWCNT, for detecting acetone gas with high sensitivity and humidity stability. The obtained nanocomposites have the structural features of a sensing material as a C8F-doped-PPy layer surrounding a single-stranded SWCNT, and a PLA layer on the outer surface of the PPy as a specific sensing layer for acetone. PLA was chemically combined with the positively charged PPy backbone and provided the ability to reliably detect acetone gas at concentrations as low as 50 ppb even at 25 °C, which is required for medical diagnoses via human breath analysis. When C8F was contained in the pyrrole monomer in a ratio of 0.1 mol, it was able to stably detect an effective signal in a relative humidity (RH) of 0–80% range.

Eco-Friendly Synthesized PVA/Chitosan/Oxalic Acid Nanocomposite Hydrogels Embedding Silver Nanoparticles as Antibacterial Materials.

PVA/chitosan (PVA/CS) composite hydrogels incorporating silver nanoparticles (AgNPs) were prepared by double-cross-linked procedures: freeze–thawing and electrostatic interactions. Oxalic acid (OA) was used both for solubilization and ionic cross-linking of CS. AgNPs covered by CS (CS-AgNPs) with an average diameter of 9 nm and 18% silver were obtained in the presence of CS, acting as reducing agent and particle stabilizer. The increase of the number of freeze–thaw cycles, as well as of the PVA:CS and OA:CS ratios, resulted in an increase of the gel fraction and elastic modulus. Practically, the elastic modulus of the hydrogels increased from 3.5 kPa in the absence of OA to 11.6 kPa at a 1:1 OA:CS weight ratio, proving that OA was involved in physical cross-linking. The physicochemical properties were not altered by the addition of CS-AgNPs in low concentration; however, concentrations higher than 3% resulted in low gel fraction and elastic modulus. The amount of silver released from the composite hydrogels is very low (<0.4%), showing that AgNPs were well trapped within the polymeric matrix. The composite hydrogels displayed antimicrobial activity against S. aureus, K. pneumoniae or P. gingivalis. The low cytotoxicity and the antibacterial efficacy of hydrogels recommend them for wound and periodontitis treatment.

Enhancing UV-shielding and mechanical properties of polylactic acid nanocomposites by adding lignin coated cellulose nanocrystals

From a perspective of sustainable development, it is desired to develop biodegradable ultra-violet (UV)-resistant and mechanically robust materials. Lignin nanofillers (LNP) are renewable and commercially available nanofillers with promising UV-shielding characteristics. However, the addition of LNP can deteriorate the mechanical properties of lignin-based composites. On the other hand, cellulose nanocrystals containing lignin can serve as a UV-shielding and reinforcing nanofiller without sacrificing the mechanical properties of nanocomposites. In this work, the UV-shielding performance, mechanical properties, and biodegradability of PLA nanocomposites containing lignin-coated cellulose nanocrystals (LCNC) were compared with PLA nanocomposites reinforced with lignin nanofillers (LNP). Nanocomposites with different content of nanofillers (i.e., 3%, and 5%) were prepared via a masterbatch approach followed by extrusion and injection molding. The morphologies of PLA nanocomposites studied by scanning electron microscopy, confirmed smooth fracture surfaces with micro sized LCNCs aggregates. However, rough fracture surfaces and uniform nanoparticle dispersion were observed in PLA nanocomposites reinforced by LNP. The UV–Vis characterization revealed a synergic effect of incorporating either LNP or LCNCs nanostructures in terms of UV light blocking ability. The addition of low content (3 wt%) LCNCs into the PLA matrix, blocked the highest amount of UV radiation, 75.3% of UV-A and 45.81% of UV-B. Degradation tests of PLA and its nanocomposites showed that the maximum weight loss of PLA nanocomposites after being hydrolytically degraded for 30 days increased from 8% for PLA to 14% for PLA-5 wt% LCNCs, and 16.7% for PLA-5%LNP. The study provides insights into PLA nanocomposite reinforced with LCNCs or LNP regarding UV protection, biodegradability, and mechanical properties.

A Sub-6 nm MnFe2O4-dichloroacetic acid nanocomposite modulates tumor metabolism and catabolism for reversing tumor immunosuppressive microenvironment and boosting immunotherapy

Adenosine and lactate accumulated in tumor microenvironment are two major causes of immunosuppression, their concurrent downregulation holds promise in effective cancer immunotherapy, but remains challenging. Here, a sub-6 nm MnFe2O4 conjugated with dichloroacetic acid (DCA) nanoparticle is developed to modulate tumor glucose metabolism and ATP catabolism for reversing the tumor immunosuppressive microenvironment. The ultrasmall MnFe2O4-DCA nanoparticle can efficiently enter mitochondria and supply oxygen, improving the bioactivity of DCA to regulate glucose metabolism and reduce lactate production ca. 100 times higher than free DCA itself. Moreover, this design significantly downregulates CD39 and CD73 expression than DCA or MnFe2O4 alone, which consequently decreases the extracellular ATP catabolism. The concurrent regulation of glucose metabolism and ATP catabolism leads to increased immunostimulatory ATP level and decreased immunosuppressive adenosine and lactate levels in tumor microenvironment, eventually amplified dendritic cells maturation, enhanced cytotoxic T lymphocyte response, and improved cancer immunotherapy efficacy.

Biodegradation of modified starch/poly lactic acid nanocomposite in soil

In this work, the effect of lactic acid grafted starch nanocrystals (g-SNCs) on the rate of the soil burial degradation of Poly (lactic acid) was studied using the weight loss measurement (wt.%), X-ray Photo Electron Spectroscopy (XPS), Fourier-Transform Infrared Spectroscopy (FT-IR) and Differential Scanning Calorimetry (DSC). The weight loss results demonstrated that the degradation rate of PLA accelerated by adding g-SNCs nanoparticles. The FT-IR analysis showed that the intensities of C-O, C=O, and C-H bond of PLA/g-SNCs are higher than neat PLA that has declined further by increasing soil burial time. The XPS displayed that the atomic percentage of the O-C=O in PLA/g-SNCs was reduced more than neat PLA after soil burial. In addition, the variation of the O/C ratio has been controlled by g-SNCs nanoparticles degradation due to the higher hydrolysis tendency of g-SNCs. Also, the DSC analysis depicted that the glass transition temperature and degree of crystallinity of PLA/g-SNCs nanocomposites obviously decreased and increased respectively despite a slight variation for neat PLA. Regarding all the above facts, it was hypothesized that the soil burial-induced degradation rate of PLA can be significantly augmented in the presence of g-SNCs.

Effects of synthetic CSH-tartaric acid nanocomposites on the properties of ordinary Portland cement

Synthetic nano CSH is well known to serve as crystal nuclei in ordinary Portland cement. In this paper, tartaric acid was used as a stabilizer to prepare nano CSH by a separate nucleation and growth steps method. The acquired samples were tested by XRD, FT-IR, TG-DSC, total organic carbon (TOC) and dynamic laser scattering (DLS) and their effect on hydration and hardening of ordinary Portland cement were investigated. The results indicated that tartaric acid intercalated the interlayer regions of CSH, and swelled the interlayer spacing from 1.288 nm to 1.398 nm. The average particle size of the CSH-tartaric acid nanocomposites（CTNs）were in the range of 60–160 nm, and increasing the concentration of tartaric acid in composites caused a smaller CTNs particle size. When present in the alkaline solution of pH 13, tartaric acid can be released from CTNs, and the higher concentration of tartaric acid in the CTNs, the more tartaric acid was released. Due to the synergistic effect of nanocrystal nucleus and tartaric acid released from CTNs, the total hydration heat declined at first and then increased and the pore structure of hardened pastes was adjusted, resulting in the increase of compressive strength at all ages.

Graphene/Nanohydroxyapatite hybrid reinforced polylactic acid nanocomposite for load-bearing applications

ABSTRACT We studied polylactic acid (PLA) nanocomposite reinforced with graphene nanoplatelets (GNP)/Nanohydroxyapatite (NHA) hybrid prepared using the melt-mixing technique. Before mixing with the GNP, NHA was surface modified using 3-aminopropyl triethoxysilane (APTES). The surface-modified NHA (mNHA) loading was constant at 5wt% while varying the GNP loading from 0.01–0.1wt%. Results show with 0.01 wt% GNP, the impact strength of the PLA/mNHA/GNP nanocomposite increased, tensile strength decreased, thermal stability, and viscoelastic properties improved significantly compared to neat PLA and PLA/mNHA. The FESEM images show the agglomeration of mNHA/GNP hybrid at higher loading (>0.05 wt%), leading to the deterioration of PLA/mNHA/GNP nanocomposite properties.

Antidiabetic Potential of Silver/Chitosan/Ascorbic Acid Nanocomposites

Background: Diabetes mellitus is the most common health problem in the world. Silver nanoparticles (AgNPs) exposed great intrinsic anti-inflammatory, antibacterial, antiviral, and antifungal activities. Chitosan is an oligosaccharide biopolymer with a great ability to lower hyperglycemia, and ascorbic acid is a water-soluble vitamin with strong antioxidant activity. Objective: The present study aimed to estimate AgNPs/chitosan/ascorbic acid nanocomposite (Ag-NCs) anti-diabetic properties in streptozotocin-induced diabetic rats. Method: Eighteen male Wistar albino rats were divided into three main groups (6 rats/group); control, diabetic, and Ag-NCs groups. Control group: after a single dose of citrate buffer at PH 4.5 (0.1 mol/L, i.p), the rats orally received 1 ml distilled water daily for four weeks. The diabetic model was induced by a single dose of streptozotocin (60 mg/kg, i.p) for type 1 diabetes and the rats orally received 1 ml distilled water daily for four weeks. The diabetic group was treated orally with Ag-NCs (0.25 mg/Kg body weight) daily for four weeks. Results: AgNPs/chitosan/ascorbic acid nanocomposite group showed a reduction in the concentrations of glucose, NO, MDA, LDL, and the activities of AST, ALT, ALP, and GGT. At the same time, it caused a general increase in insulin, albumin, TB, TC, TG, HDL, CAT, SOD, and GSH levels. The histopathological investigation illustrated regeneration of damaged pancreatic beta cells and a clear improvement in the hepatic architecture. Conclusion: The suggested mechanism of action for Ag-NCs in decreasing diabetic complications in the liver involved two pathways; the hypoglycemic activity and the antioxidant role of AgNPs, chitosan, and ascorbic acid.

Smartphone-Based Electrochemical System for Biosensors and Biodetection.

With the advantages of high popularity, convenient operation, open-source operation systems, high resolution imaging, and excellent computing capabilities, smartphones have been widely used as the core of detection system for calculation, control, and real-time display. Hence, smartphones play an important role in electrochemical detection and optical detection. Smartphone-based electrochemical systems were combined with screen-printed electrode and interdigital electrodes for in situ detection. The electrodes were modified with biomaterials, chemical materials, and nanomaterials for biosensors and biodetection, such as 3-amino phenylboronic acid nanocomposites, graphene, gold nanoparticles, zinc oxide nanoparticles, carbon nanotubes, proteins, peptides, and antibodies. With the modified electrodes, the smartphone-based impedance system was used to detect acetone, bovine serum albumin, human serum albumin, and trinitrotoluene, while smartphone-based amperometric system was employed to monitor glucose, ascorbic acid, dopamine, uric acid, and levodopa. The smartphone-based electrochemical system for biosensors and biodetection has provided miniaturized and portable alternative for diagnosis, which is promising to find application in point-of-care testing (POCT).

Fabrication and the barrier characterization of the cellulose nanofibers/organic montmorillonite/poly lactic acid nanocomposites

AbstractThe hydrophobic modification of cellulose nanofibers (CNF) was carried out via free radical polymerization using methyl methacrylate (MMA) as the monomer to improve the compatibility between CNF and poly lactic acid (PLA). Followed by the preparation of the novel nanocomposites in combination of the organic montmorillonite and the substrate. The resulting nanocomposites were then coated on paper surface using a cast‐coating process in an attempt to improve the barrier properties towards water vapor and oxygen. In addition, the composite films are prepared via a solution casting method. The water vapor transmission rate (WVTR), water vapor permeability (WVP), oxygen transmission rate (OTR), and tensile strength of the as‐prepared films were systematically measured. The corresponding results demonstrated that the WVTR, WVP and OTR decreased with the addition of a certain content of MCNF in coatings. 0.2 wt% MCNF is the optimum content, showing the best gas resistance and tensile performance. The lowest value of WVTR and WVP are 10.30 g/(m2⋯24 h) and 3306.58 g⋯μm/(m2⋯24 h) for films with 0.2 wt% MCNF added, which is 88.23% and 26.05% lower than that of PLA composite film without NFC.

Silver/Chitosan/Ascorbic Acid Nanocomposites Attenuates Bacterial Sepsis in Cecal Ligation and Puncture Rat Model

Silver/Chitosan/Ascorbic Acid Nanocomposites Attenuates Bacterial Sepsis in Cecal Ligation and Puncture Rat Model

Synthesis, Characterization and Adsorption Studies of a Graphene Oxide/Polyacrylic Acid Nanocomposite Hydrogel

The AAc/GO nanocomposite hydrogel was successfully employed as a polymeric Nano sorbent of the removal efficiency of M G dye from the model. The complication of the mechanism of the adsorption system was completely exposed by examining how solution pH affects adsorption, Ionic strength isotherm models, kinetic models, and thermodynamics. The adsorption of the MG dye was greatly dependent on the solution pH. The Freundlich model has been demonstrated to be the most accurate in describing the MG dye sorption, whilst the Langmuir model was shown to be the least accurate. Additionally, these integrated mechanisms fit nicely within the framework of a pseudo-second-order model. Additionally, the contact time at equilibrium short (ten minutes) required to MG removes demonstrates the AAc/GO nanocomposite hydrogel can be considered an efficient and potentially useful adsorbent for MG removal from industrial effluents.

Photocatalytic CO2 reduction with new band gap energy evaluation from spectroscopic relationship of graphene-Mg2CuSnCoO6 composite bridged with organics

A new structure of graphene-Mg 2 CuSnCoO 6 composite bridged with gallic acid (GMG) was synthesized with a novel method. Band gap energy of the newly synthesized nanocomposite was evaluated with a laser-wavelength region and DRS method. Evaluation and analysis were based on the relationship among XRD, HRTEM, XPS, Raman scattering, and computer simulated model structure. Changes in the structure of graphene or graphene-based composite were associated with location changes of the valence band and the conduction band. Electron density was used to confirm the number of electrons by computer simulation. Finally, such graphene-Mg 2 CuSnCoO 6 -gallic acid nanocomposite was used for photocatalytic CO 2 reduction into methanol. Under UV-light irradiation, the highest methanol yield was 5.576% with 0.6 g of scavenger. This work might offer a promising strategy for measuring band gap energies of different types of semiconductors. • Synthesis of new-structured Graphene-Mg 2 CuSnCoO 6 composite bridged with Gallic acid. • The evaluation of new band gap energy value. • Photocatalytic activity for the CO 2 reduction by novel ternary nanocomposite. • The high methanol production rate with scavengers. • High stability and photocatalytic efficient properties for production of solar fuel.

Silver/chitosan/ascorbic acid nanocomposites ameliorate diabetic nephropathy in the model of type 1 diabetes

Aims: The present study aimed to evaluate anti-diabetic properties of AgNPs/chitosan/ascorbic acid nanocomposites (Ag-NCs) in streptozotocin-induced diabetic rats. Main methods: Eighteen male Wistar albino rats were divided into three main groups (6 rats/group); control, diabetic and Ag-NCs groups. Control group: after a single dose of citrate buffer (0.1 mol/l, i.p), the rats orally received 1 ml distilled water daily for four weeks. The diabetic model was induced by a single dose of streptozotocin (60 mg/kg, i.p) for type 1diabetes. Diabetic groups were treated orally with and Ag-NCs (0.25mg/Kg body weight) daily for four weeks. Key findings: AgNPs/chitosan/ascorbic acid nanocomposite group showed a reduction in the concentrations of glucose, NO, MDA, creatinine, urea and uric acid. At the same time, it appeared a general increase in insulin, CAT, and SOD activities and GSH concentration. The histopathological investigation illustrated a clear improvement in renal architecture. Significance: The suggested mechanism of action for Ag-NCs in decreasing diabetic nephropathy includes two pathways; the hypoglycemic activity and the antioxidant role of Ag-NCs

Silver/chitosan/ascorbic acid nanocomposites ameliorate diabetic nephropathy in the model of type 1 diabetes

Silver/chitosan/ascorbic acid nanocomposites ameliorate diabetic nephropathy in the model of type 1 diabetes

Preparation of Collagen/Aspartic Acid Nanocomposite Fibers and Their Self-Assembly Behaviors

ABSTRACT Collagen is a promising biomaterial with excellent biocompatibility, low immunogenicity, and good biodegradability. However, the poor mechanical properties of regenerated collagen fibers, which are susceptible to thermal denaturation and rapid degradation, remain a substantial challenge. In this work, aspartic acid (Asp) was incorporated to improve the performance of collagen fibers. The self-assembly behavior of collagen molecules in the presence of Asp was investigated, and the structure and properties of the collagen/Asp composite fibers were discussed. Their results showed that there are strong molecular interactions between the negatively charged Asp and the positively charged collagen molecules in acidic conditions. The mechanical properties and thermal stability of composite fibers are significantly improved compared with those of pure collagen fibers. Electrostatic interactions are the main factors affecting the self-assembly structure of collagen molecules, the alignment of collagen microfibrils, and the mechanical and thermal performances of composite fibers. This work provides a simple and environmentally friendly pathway to generate collagen-based fiber materials with better properties and has the potential to be used in a variety of biomedical applications.

Combined Effects of Cellulose Nanofiber Nucleation and Maleated Polylactic Acid Compatibilization on the Crystallization Kinetic and Mechanical Properties of Polylactic Acid Nanocomposite.

This work investigated the combined effects of CNF nucleation (3 wt.%) and PLA-g-MA compatibilization at different loadings (1–4 wt.%) on the crystallization kinetics and mechanical properties of polylactic acid (PLA). A crystallization kinetics study was done through isothermal and non-isothermal crystallization kinetics using differential scanning calorimetry (DSC) analysis. It was shown that PLA-g-MA had some effect on nucleation as exhibited by the value of crystallization half time and crystallization rate of the PLA/PLA-g-MA, which were increased by 180% and 172%, respectively, as compared to neat PLA when isothermally melt crystallized at 100 °C. Nevertheless, the presence of PLA-g-MA in PLA/PLA-g-MA/CNF3 nanocomposites did not improve the crystallization rate compared to that of uncompatibilized PLA/CNF3. Tensile strength was reduced with the increased amount of PLA-g-MA. Contrarily, Young’s modulus values showed drastic increment compared to the neat PLA, showing that the addition of the PLA-g-MA contributed to the rigidity of the PLA nanocomposites. Overall, it can be concluded that PLA/CNF nanocomposite has good performance, whereby the addition of PLA-g-MA in PLA/CNF may not be necessary for improving both the crystallization kinetics and tensile strength. The addition of PLA-g-MA may be needed to produce rigid nanocomposites; nevertheless, in this case, the crystallization rate of the material needs to be compromised.