Bleaching Treatment Research Articles

Influência da moldeira contendo dentifrício na redução da sensibilidade causada por clareamento dental de consultório

Objetivo: avaliar clinicamente a utilização de dentifrício dessensibilizante, aplicado através de moldeira plástica, na redução da dor e variação de cor causadas pela técnica de clareamento dental de consultório. Material e Métodos: Para o estudo foram selecionados 24 voluntários que foram submetidos ao clareamento dental de consultório em 3 sessões clínicas com intervalo de uma semana, com a utilização de gel clareador (peróxido de hidrogênio - 35%). Na noite referente a cada sessão de clareamento, os voluntários utilizaram uma moldeira plástica por 4 horas contendo um dos dentifrícios relativos aos grupos experimentais: (1) Sucralose (S); (2) Fosfato de sódio (FS) e Silicato de cálcio (SC) (Tecnologia NR-5). A dor foi avaliada antes do uso da moldeira plástica com dentifrício (S1, S3, S5) e após (S2, S4, S6) durante 4 semanas, utilizando a escala numérica analógica com escores de 0 a 10. Para a variação de cor (?E) utilizou-se espectrofotômetro (Easyshade). Resultados: O grupo FS e SC apresentaram redução da dor em relação aos demais grupos (p<0,05). Houve uma redução da dor após o uso da moldeira com dentifrício (S2, S4, S6) por 4h e não houve diferença para ?E entre os grupos experimentais após o tratamento clareador (p=0,91). Conclusão: Conclui-se que a utilização de dentifrício dessensibilizante com FS e SC (Tecnologia NR-5) em moldeira plástica foi eficiente para a redução da dor causada por clareamento dental de consultório e o uso de dentifrício dessensibilizante não influenciou a eficácia do tratamento clareador.

Dental bleaching efficacy and impact on demineralization susceptibility of simulated stained-remineralized caries lesions

ObjectivesTo evaluate the efficacy of different bleaching systems on artificially created stained-remineralized caries lesions; and to assess the susceptibility of the bleached lesions to further demineralization. MethodsHuman enamel specimens were sectioned, polished, demineralized, and randomly divided into six groups (n = 21) to create stained-remineralized lesions, either non-metallic (non-Met: G1, G2 and G3) or metallic (Met: G4, G5 and G6). G1 and G4 received no bleaching treatment, while G2 and G5 were treated with 15% carbamide peroxide (at-home bleaching protocol; 4 h/d×7), and G3 and G6 with 40% hydrogen peroxide (in-office bleaching protocol; 20min × 3). Susceptibility to further demineralization was tested after bleaching treatment. Lesion mineral loss and depth were measured by transversal microradiography, and color change by spectrophotometry. Outcomes were analyzed using ANOVA models followed by Fisher’s PLSD tests (α = 0.05). ResultsMetallic-stained lesions were significantly darker (all p < 0.001) and more resistant to bleaching (p < 0.005) than non-Met ones. For both stain types, the at-home bleaching protocol was more effective than the in-office (p < 0.005); however, it also increased the lesion susceptibility to demineralization (p < 0.05) [ΔΔZ mean ± SD ranging from 205 ± 73 to 313 ± 188 (at home) vs. 132 ± 45 to 206 ± 98 (in office); p < 0.05]. After bleaching, non-Met lesions were significantly more susceptible to demineralization (p < 0.05), with the ΔΔZ ranging from 206 ± 98 to 313 ± 188 compared to Met lesions ranging from 132 ± 45 to 205 ± 73. ConclusionsAt-home bleaching protocol presented greater bleaching efficacy compared to in-office bleaching protocol. After bleaching, metallic-stained lesions were more resistant to subsequent demineralization compared to non-metallic stained lesions. Clinical significanceBleaching stained-arrested caries lesions may improve aesthetics but also increase susceptibility to demineralization, depending on the type of stain involved and bleaching system used.

Effects of nano-hydroxyapatite paste on enamel microporosity after bleaching treatment

Bleaching or teeth whitening is a popular dental conservative treatment to enhance aesthetics. Bleaching treatment in many cases has successfully improved aesthetics but still remains the side effects. It can cause some changes in enamel structure leading to demineralization characterized by the emergence of microporosity on the enamel surface. Nano-hydroxyapatite is potential to re-mineralize earlyenamel lesions. This study aims to identify the effect of nano-hydroxyapatite on enamel microporosity after bleaching treatment. Twelve rabbits were randomly divided into two groups. The control and treatment group administered a placebo and nano-hydroxyapatite paste respectively, for 7 days after bleaching treatment. Once the treatment was completed, the rabbit was sacrificed, the jaw was decapitated, upper and lower incisors of the rabbit were separated from the jaw. Subsequently, the sample preparation wasconducted for examination of enamel microporosity depth by using scanning electron microscope. The results showed the control group had more microporositycompared to the treatment group. The independent t-test result showed that enamel microporosityhad a significant value of 0.003 (p &lt;0.05) meaning that enamel microporosity between both groups had a significant difference. The conclusion of this study was administration of nan-hydroxyapatite paste reduced enamel microporosityin the administration of nano-hydroxyapatite pastes compared to the placebo pastes after bleaching treatment.

Differences in surface roughness of enamel after whey-extract application and CPP-ACP in post extracoronal-tooth bleaching

Demineralization is a process of partial or full tooth mineral loss which caused by acidic environment, for example the side effect of extracoronal bleaching treatment. Demineralization increases enamel surface roughness which leads plaque accumulation. Whey extract and calcium phosphopeptide-amorphous calcium phophate (CPP-ACP) contain calcium and phosphate that can stop the demineralization through remineralization process. This study aimed to determine the differences of enamel surface roughness after whey extract and CPP-ACP application post- extracoronal bleaching. Experimental laboratory with pre- and post-test control group design was performed on 24 first maxillary premolars which devided into 3 groups. On group I, specimens were immersed in artificial saliva. Specimens in group II were immersed in whey extract meanwhile specimens were immersed in CPP-ACP on group III. Whey extract and CPP-ACP immersions were conducted 10 minutes every 12 hours for 15 days. The enamel surface roughness test was performed twice, after extracoronal bleaching treatment and after 15 days remineralization agent application. This study result indicated significant differences between group I and group II and between group I and group III (p&lt;0.05), but there was no significant difference between group II and group III (p&gt;0.05). This study showed whey extract decreased more enamel surface roughness than CPP-ACP but the difference was not significant statistically. So, whey extract and CPP-ACP showed similar remineralization potential.

The Effect of Different Bleaching Treatments and Thermal-Mechanical Cycling on the Shear Bond Strength of Orthodontic Brackets.

The aim of the present study was to compare the shear bond strength (SBS) of orthodontic brackets bonded to the enamel after at-home and in-office bleaching treatments. Sixty bovine incisors were subjected to initial color readings and then classified into three groups: CP (16% carbamide peroxide), HP (35% hydrogen peroxide), and C (control). After treatments, new color readout was obtained, and orthodontic brackets were bonded to the bleached area. Half of the samples of each group (n=10) were subjected to thermal-mechanical cycling (TMC) testing (1,200,000 cycles; 44.2 N; 2 Hz/s), whereas the other half were stored in distilled water at 37 °C for 24 h. Samples were subjected to the SBS test at a speed of 0.5 mm/min. The mean SBS was analyzed (two-way ANOVA, Bonferroni test, p<0.05), and the fracture patterns were classified as adhesive, cohesive, and mixed types. There was no difference (p>0.05) in SBS values between the samples subjected to TMC and the cycled samples in any group. Samples subjected to carbamide peroxide presented lower SBS (p<0.05) than the non-cycled ones. Enamel adhesive fractures were higher in the bleached groups than in the control group, which presented mixed fractures prevalence, regardless of whether it was subjected to TMC or not. Thermal-mechanical cycling was not significant for SBS of orthodontic brackets, but tooth bleaching was a factor.

Improved mechanical properties of k-carrageenan-based nanocomposite films reinforced with cellulose nanocrystals

This work investigates the isolation of cellulose nanocrystals (CNC) from sugarcane bagasse (SCB) waste and the evaluation of their mechanical reinforcement capability for k-carrageenan biopolymer. The results from Atomic Force Microscopy and Transmission Electron Microscopy indicated the successful extraction of CNC from SCB following alkali, bleaching and acid hydrolysis treatments. The CNC displayed a needle-like structure with an average aspect ratio of 55. The surface functionality of the CNC was evaluated by Fourier Transform Infrared Spectroscopy and X-ray Photoelectron Spectroscopy measurements. X-ray diffraction studies showed that the as-extracted CNC exhibit cellulose I crystalline structure, with a crystallinity index of 80%. The obtained CNC were dispersed into k-carrageenan biopolymer matrix at various CNC contents (1, 3, 5 and 8 wt%) and the prepared films were further characterized. The incorporation of CNC decreased the light transmittance values but enhanced the mechanical properties compared with the neat k-carrageenan film. Empirical Halpin-Tsai model was used to predict the CNC dispersion within k-carrageenan matrix. The obtained nanocomposite films have the potential to be used as food packaging material.

Application of quantitative light-induced fluorescence technology for tooth bleaching treatment and its assessment: An in vitro study.

This study aimed to determine the efficacy of a combination of photocatalysts-hydrogen peroxide at a low concentration (3.5%) and titanium dioxide (TiO2)-activated at a wavelength of 405 nm using quantitative light-induced fluorescence (QLF) technology, and to quantify their tooth-bleaching efficacy using fluorescence images obtained from QLF technology. Forty bovine incisors were extrinsically stained according to Stookey's method, and were randomly divided into four groups (n = 10 per group). Two bleaching solutions were prepared by mixing 3.5% H2O2 with 0.05% of anatase and rutile TiO2 powders. These solutions were applied to the stained teeth using a microbrush and then irradiated for 15 min at either 306 or 405 nm to activate the bleaching agent. The color difference (ΔE*) was assessed before and after every 5 min of treatment. The ΔE* and the changes in the fluorescence loss (ΔΔF) were obtained from white-light and fluorescence images, respectively. All of the low-H2O2/TiO2 treatments caused significant tooth-bleaching efficacy after irradiation at 306 and 405 nm (p < 0.05). The results did not differ significantly between the two wavelengths (p > 0.05), but the bleaching efficacy was greater with anatase TiO2 at 306 nm and rutile TiO2 at 405 nm. Analysis of the fluorescence images revealed that the ΔF values increased significantly in all groups with the treatment time (p < 0.05). There was a statistically significant correlation between ΔE* and the change in ΔΔF (r = 0.822, p < 0.001). Combining low-H2O2/TiO2 with QLF technology at 405 nm has an efficacy of tooth-bleaching as a less harmful and biofriendly method, while the fluorescence images obtained by QLF technology could be used to assess tooth-bleaching.

Physicochemical changes in enamel submitted to pH cycling and bleaching treatment.

ObjectiveThe purpose of this study was to assess the hardness, mineral content, surface roughness, and micromorphology of sound and slightly demineralized enamels, before and after bleaching procedure using 10% carbamide peroxide.MethodsSixty bovine dental blocks were randomly divided into the following two groups: 30 slabs were submitted to three cycles of pH and 30 slabs were noncycled. Hardness (n=10) was measured using the microhardness tester with Knoop indenter under a 50 g load for 5 seconds. The calcium/phosphate (Ca/P) ratio (n=10) was obtained using a micro-energy-dispersive X-ray fluorescence (μ-EDXRF) spectrometer. The measurement of roughness average (n=10) was performed using a surface roughness tester. Specimens were bleached 6 hours/day during 21 days, and then, physicochemical properties were re-evaluated. Two additional specimens were carried out to evaluate surface micromorphology using the scanning electron microscopy. Data were statistically analyzed by ANOVA and Tukey’s test (α=0.05).ResultsSound and slightly demineralized enamels showed no difference in Ca/P ratio after dental bleaching according to the μ-EDXRF analysis, but the Ca/P ratio decreased after bleaching for slightly demineralized enamel. Bleaching treatment decreased the hardness and increased the surface roughness, causing micromorphology alterations.ConclusionTherefore, bleaching procedure promoted change in bovine enamel surface and increased the demineralization of slightly demineralized enamel but not affected the mineral content of sound enamel.

Effect of At-Home Bleaching on Oxygen Saturation Levels in the Dental Pulp of Maxillary Central Incisors.

The present study assessed oxygen saturation (SaO2) levels before, during, and after at-home bleaching treatment in the pulps of healthy maxillary central incisors. SaO2 levels were measured in 136 healthy maxillary central incisors using a pulse oximeter. The bleaching protocol consisted of 10% carbamide peroxide gel placed in individual trays and used for four hours daily for 14 days. SaO2 levels were assessed before bleaching (T0), immediately after the first session (T1), on the 7th day of treatment (T2), on the 15th day (the day following the last session) (T3), and 30 days after completion of the bleaching protocol (T4). Data were statistically analyzed using generalized estimating equations (GEE), Student's t test (p<0.05) and Pearson's correlation. Mean pulp SaO2 levels were 85.1% at T0, 84.9% at T1, 84.7% at T2, 84.3% at T3, and 85.0% at T4. Gradual reductions in SaO2 levels were observed, with significant differences (p<0.001) during the course of home bleaching treatment. However, 30 days after the end of the bleaching protocol, SaO2 levels returned to baseline levels. Home bleaching caused a reversible transient decrease in SaO2 levels in the pulps.

The physical and chemical disruption of human hair after bleaching - studies by transmission electron microscopy and redox proteomics.

To understand the structural and chemical effects of cosmetic peroxide bleaching on human hair. Human hair was progressively bleached using alkaline peroxide-persulphate treatment. Proteins lost through leaching were examined using amino acid analysis and mass spectrometric sequencing. Fibre damage was assessed using transmission electron microscopy, amino acid analysis and redox proteomics. Protein loss through leaching increased with bleaching severity. Leached proteins were not limited to the cuticle, but also included cortical intermediate filaments and matrix keratin-associated proteins. The leached proteins were progressively oxidized as bleaching severity increased. Bleached fibres demonstrated substantial damage to the cuticle layers and to the cortex. Extensive melanin granule degradation was present after the mildest bleach treatment. Protein oxidation in bleached fibres was principally in cortical intermediate filaments - the most abundant hair proteins - and targeted the sulphur-containing amino acids, particularly the conversion of cystine disulphide bonds to cysteic acid. Peroxide chemical treatments quickly access the cortex, causing untargeted oxidative damage across the fibre in addition to the desired loss of melanin. Peroxide ingress is likely facilitated by the considerable structural degradation caused to the cuticle layers of hair fibres. The consequences of the peroxide action within the cuticle and cortex are oxidation of the proteins, and subsequent protein loss from the fibre that correlates to bleaching severity.

Influence of treatment duration on the efficacy of at-home bleaching with daytime application: a randomized clinical trial.

The aim of this study is to determine whether prolonging the daytime at-home bleaching treatment by 1week increases the bleaching effect without causing more side effects. Fifty participants were randomly divided into two groups, (A) with a 14-day treatment and (B) with a 21-day treatment. A gel with 10% carbamide peroxide was applied for 2h a day in custom trays. Color measurement was performed using a dental spectrophotometer on the right maxillary central incisor and the canine at baseline, at the end of treatment, and 1 and 6months afterwards. Daily, participants recorded their tooth sensitivity and gingival irritation. At the end of the treatment, the ΔE00 of group B (5.77 ± 2.15) was significantly higher than the ΔE00 of group A (4.74 ± 1.94) (p = 0.005 (95% CI: - 2.13 to - 0.39)). After 6months, tooth color was more stable in group B. The ΔSGU values between the different appointment times were higher in the 3-week group. Participants from group B reported more side effects, but statistically, there were no differences compared with group A (p = 0.225 for tooth sensitivity and p = 0.758 for gingival irritation). Daytime application of at-home bleaching for 3weeks achieves greater bleaching results than for 2weeks, immediately after treatment and 1 and 6months afterwards. However, slightly more side effects could occur. When daytime application of at-home bleaching is required, the treatment duration should be prolonged from 2 to 3weeks to achieve greater and more stable results.

In-office and walking bleach dental treatments on endodontically-treated teeth: 25 years follow-up.

Many techniques have been evolved for the purpose of managing discoloured non-vital tooth such as dental bleaching, restorative and prosthetic treatment. In order to achieve better control on the patients, in-office and intra-coronal bleaching procedures were introduced in clinical practice. Such techniques usually use higher whitening agent concentrations activated by means of heat or light sources, resulting in improved color stability in the long term. The aim of this study was to evaluate the color stability, after 25 years, of endodontically-treated teeth subjected to in-office and walking bleach dental treatments with carbamide peroxide. A population of patients with a single endodontic treatment on an incisor teeth was recruited. All the teeth selected for the study were subjected to both in-office intra-coronal dental bleaching and walking bleach technique with 10% carbamide peroxide gel. The patients were recalled at follow-up every 12 months for a total observational period of 25 years. After 25 years of clinical service on 40 patients, an optimal tooth color stability in relation to adjacent teeth was evidenced in 34 patients, while 6 patients were classified as failures, since a color mismatch of two or more shades were noticed. Consequently, a success rate of 85% was reported after 25 years. Ten percent carbamide peroxide proved to be an effective dental whitening agent in the long-term for endodontically-treated.

Isolation and characterization of cellulose nanocrystals from pineapple crown waste and their potential uses

Pineapple crown is an important source of cellulose that is still going to waste because of the lack of knowledge about their economic uses. The isolation of cellulose nanocrystals (CNC) from pineapple crown leaf (PCL) wastes arises as an important alternative to use PCL wastes in high value-added applications, and has not been reported yet. In this study, CNC were successfully extracted from PCL wastes using chemical treatments followed by acid hydrolysis using sulfuric acid. FTIR results confirmed the removal of the non-cellulosic compounds of PCL through the mercerization and bleaching treatments. SEM and AFM showed that the diameter of PCL fibers was reduced from 18 μm to 39 nm after the hydrolysis reaction, resulting in CNC with rod-like shape. The obtained CNC showed cellulose I crystalline structure with high crystallinity index (73%). The thermal degradation of CNC started at 124 °C, what was attributed to the presence of surface sulfate groups identified by elemental analysis. The high hydrophilicity of CNC was verified by its high moisture content and absorption. The results showed that the CNC isolated from PCL have interesting properties to be used in many liquid media applications, besides their use as reinforcement in nanocomposites.

Tensile and water absorption properties of solvent cast biofilms of sugarcane leaves fibre-filled poly(lactic) acid

This research covers the preparation of poly(lactic acid) (PLA)/sugarcane leaves fibre (SLF) biofilms via a solvent-casting method. The results showed that the tensile strength and Young’s modulus of PLA/SLF biofilms increased with the increasing of SLF content. Nevertheless, the elongation at break showed an opposite trend as compared to tensile strength and Young’s modulus of biofilms. Moreover, water absorption properties of PLA/SLF biofilms increased with the increasing of SLF content. In contrast, the tensile strength and Young’s modulus of biofilms were enhanced after bleaching treatment with hydrogen peroxide on SLF, but the elongation at break and water absorption properties of bleached biofilms were reduced due to the improvement of filler–matrix adhesion in biofilms. The tensile and water properties were further discussed using B-factor and Fick’s law, respectively. Furthermore, the functional groups of unbleached and bleached SLF were characterized by Fourier transform infrared analysis.

Novel N-chloramine precursors for antimicrobial application: synthesis and facile covalent immobilization on polyurethane surface based on perfluorophenyl azide (PFPA) chemistry

To control the pathogen cross contaminations on medical material surface, there is a pressing need to develop antimicrobial materials with highly efficacious surface biocidal activity. In this work, N-chloramine precursors containing a quaternary ammonium unit and perfluorophenyl azide unit were synthesized and covalently immobilized on inert polyurethane (PU) film upon UV light irradiation. The surface modification was confirmed by contact angle, Fourier transform infrared (ATR FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) analyses. After bleaching treatment, satisfactory biocidal activity was achieved for the surface-modified PU films. It was found that the introduced surface QA center contributed an even faster surface contact killing behavior and that precursors with a longer structural linker caused higher surface chlorine content and higher antimicrobial efficacy. This approach provides a novel and facile method that enables the covalent immobilization of N-chloramine precursors on inert polymeric surface to produce durable antimicrobial materials.

Gamma Irradiation-Assisted Synthesis of Cellulose Nanocrystal-Reinforced Gelatin Hydrogels.

Herein, we describe the use of gamma irradiation to prepare hydrogels comprising α-cellulose and cellulose nanocrystal (CNC)-reinforced gelatin in the absence of crosslinking agents. In this study, cellulose was extracted from rice husks by an alkali and bleaching treatment followed by acid hydrolysis to produce CNC. A semi-interpenetrating network (semi-IPN) of hydrogels was developed by the miscibility between gelatin and cellulosic materials. Compared to those prepared from α-cellulose, hydrogels prepared by dispersion of CNCs exhibited remarkably enhanced stiffness and swelling properties, which was ascribed to the uniform distribution of CNCs and their increased crystallinity. Improved pore structure, arrangement, and rigidity of CNC-reinforced gelatin hydrogels, which induced the swelling mechanism resulting in higher and faster water uptake was observed with a scanning electron microscope (SEM), compared to cellulose-reinforced gelatin hydrogels. Moreover, in vitro drug profiling demonstrated that CNC/gelatin hydrogels exhibit good drug loading/release behavior and are thus suitable for use in drug-delivery applications.

How the surface wettability and modulus of elasticity of the Amazonian paricá nanofibrils films are affected by the chemical changes of the natural fibers

The use of natural resources for the production of nanostructured cellulosic films of high quality could reduce pollution and raw material costs for cellulose industry. This work provides innovative information about the use of Amazonian species not explored in studies involving the production of nanostructured films, as well as the evaluation of important characteristics that may be decisive for the destination of the product. The aim of this study was to modify Schizolobium parahyba var. amazonicum (parica) waste fibers through alkaline (NaOH) and bleaching (NaClO2) treatments for cellulose nanofibrils (CNFs) production and evaluate the characteristics of the nanofibrils and the surface as well as the mechanical resistance of the films obtained. The alkaline treatment was carried out with sodium hydroxide (5% NaOH solution (w/v); 2 h), while the bleaching was performed using sodium chlorite and glacial acetic acid (1.5 g NaClO2; 10 drops of glacial acetic acid; 1 h). The treatments were performed in sequence, producing nanofibrils after alkaline treatment and after bleaching. Lignin content did not change with the alkaline treatment, but it significantly decreased with bleaching (from 26.1 to 6.8%). Hemicelluloses content decreased with the sequence of treatments. FTIR results showed that the mechanical defibrillation caused disruption of the fiber bonds. The temperature of thermal degradation observed in DTG analysis increased from the natural fibers (243 °C) to alkaline + bleached fibers (255 °C). The defibrillation process led to higher thermal stability of the alkaline + bleached nanofibrils in comparison to fibers. Moreover, films were prepared from the obtained CNFs and evaluated by the mechanical properties and surface contact angle. The mechanical properties showed values of 6.93 ± 0.18 GPa for modulus of elasticity (MOE) for the films produced from material which was submitted to the bleaching treatment. The results highlighted a more hydrophobic surface of the film produced with the CNFs generated from the bleached fibers. The results of mechanical properties showed the superiority of the films produced from the alkaline + bleached fibers.

Physical and Thermal Properties of Cellulose Nanofibers (CNF) Extracted from Agave Cantala Fibers Using Chemical-Ultrasonic Treatment

Cellulose nanofibers (CNF) have been extracted from agave cantala fibers by using chemical-ultrasonic treatment. The raw fibers have been subjected to alkali and bleaching treatments followed by acid-hydrolysis. The characteristics of cantala fibers such as their morphology through scaning electron microscope (SEM), Transmission electron micrsoscop (TEM), fourier transform analysis (FTIR), x-ray diffraction (XRD) and thermogravimetric analysis (TGA) have been analyzed. The CNF extracted from cantala fiber had uniform diameters of 45-50 nm with 800-2000 nm in lengths. Change in the FTIR spectra of CNF indicated that hemicellulose and lignin were significantly removed during chemical treatment. The crystallinity index of CNF increased when chemical treatment followed by optimum-time ultrasonic treatment was applied. The TGA discovered that CNF was stable until 271 oC. Based on the properties, the CNF would be suitable for reinforcement of nanocomposites.

Biocidal poly (vinyl alcohol) films incorporated with N-halamine siloxane

Abstract An N-halamine siloxane precursor γ-(β-hydroxyl-γ-5,5- dimethylhydantoin)aminopropyltrithoxysilane (abbreviated as GHAPA) was synthesized in this study. GHAPA was mixed with PVA solution to prepare PVA/GHAPA cross linked film with an antimicrobial function. The obtained PVA/GHAPA cross linked film was characterized by TGA, DSC and XRD. Upon dilute household bleach treatment, the chlorinated PVA/GHAPA cross linked film could inactivate Staphylococcus aureus and Escherichia coli O157:H7 completely with concentrations of 4.57 × 107cfu and 2.70 × 107cfu within 5 and 10 min, respectively, and 99.9995% of Escherichia coli O157:H7 could be inactivated within 5 min. The antimicrobial results showed that the chlorinated films substantially outperformed the unchlorinated control samples. The biocidal films may serve as potential materials for food packaging and biomedical applications.

Environmentally-Friendly Extraction of Cellulose Nanofibers from Steam-Explosion Pretreated Sugar Beet Pulp.

Cellulose nanofibers (CNFs) with an average diameter of 22 nm were prepared from sugar beet pulp (SBP) via an environmentally-friendly method. Steam-explosion pretreated SBP was treated with hydrogen peroxide (H2O2) bleaching, high-speed blending, and ultrasonic treatment. Thermogravimetric analysis showed that hemicellulose was partially hydrolyzed in the steam-cooking stage, pectin was removed in the explosion stage, and lignin was removed by H2O2 bleaching. The removal of non-cellulosic components was confirmed by Fourier-transform infrared (FT-IR) spectroscopy. Morphological analysis showed that steam-explosion pretreatment largely extracted the binder materials of hemicellulose and pectin. This exposed the microfibrillated cellulosic fibers, which promoted subsequent nanofibrillation. X-ray diffraction showed that the CNFs had a crystallinity index of 62.3%. The CNFs had good thermal stability, and thus have potential for use as fillers in polymer matrices. The only chemical reagent used in this green method was H2O2. Combining H2O2 bleaching with steam explosion, high-speed blending, and ultrasonic treatment reduced the overall energy consumption and increased the efficiency of the CNFs extraction. The method, therefore, has potential application in industrial processes.