Nanochitin: Chemistry, Structure, Assembly, and Applications.

Chitin, a fascinating biopolymer found in living organisms, fulfills current demands of availability, sustainability, biocompatibility, biodegradability, functionality, and renewability. A feature of chitin is its ability to structure into hierarchical assemblies, spanning the nano- and macroscales, imparting toughness and resistance (chemical, biological, among others) to multicomponent materials as well as adding adaptability, tunability, and versatility. Retaining the inherent structural characteristics of chitin and its colloidal features in dispersed media has been central to its use, considering it as a building block for the construction of emerging materials. Top-down chitin designs have been reported and differentiate from the traditional molecular-level, bottom-up synthesis and assembly for material development. Such topics are the focus of this Review, which also covers the origins and biological characteristics of chitin and their influence on the morphological and physical-chemical properties. We discuss recent achievements in the isolation, deconstruction, and fractionation of chitin nanostructures of varying axial aspects (nanofibrils and nanorods) along with methods for their modification and assembly into functional materials. We highlight the role of nanochitin in its native architecture and as a component of materials subjected to multiscale interactions, leading to highly dynamic and functional structures. We introduce the most recent advances in the applications of nanochitin-derived materials and industrialization efforts, following green manufacturing principles. Finally, we offer a critical perspective about the adoption of nanochitin in the context of advanced, sustainable materials.

Analysis of adjacent vertebral fracture after percutaneous vertebroplasty: do radiological or surgical features matter?

PURPOSE: To report the incidence and risk factors of adjacent vertebral fracture (AVF) after percutaneous vertebroplasty (PVP) in patients with osteoporotic vertebral compression fractures (OVCFs). We focused to investigate effect of radiological or surgical features on AVF. METHODS: All patients with OVCFs who were treated with PVP between January 2016 and December 2019 were retrospectively reviewed. Patients were followed up at least 12 months after procedure according to treatment protocol. AVF was defined as postoperatively recurrent intractable back pain and subsequently presence of fracture on magnetic resonance imaging (MRI) in adjacent levels. Clinical, radiological, and surgical factors potentially affecting occurrence of AVF were recorded and analyzed using univariate and multivariate analysis. RESULTS: Totally, 1077 patients with 1077 fractured vertebrae who underwent PVP were enrolled in the study, after inclusion and exclusion criteria were met. Mean follow-up time was 24.3 ± 11.9 months (range, 12-59 months). AVF was identified in 98 (9.1%) patients. Univariate analysis showed that seven significant factors related to AVF were older age, non-traumatic fracture, cortical disruption on anterior wall, cortical disruption on lateral wall, basivertebral foramen, type-B leakage and type-C leakage. In multivariate analysis, two clinical factors, older age (P = 0.031) and non-traumatic fracture (P = 0.002), were significantly associated with AVF. However, any radiological or surgical factor did not reach significance in final model analysis. CONCLUSIONS: Incidence of AVF after PVP in patients with OVCFs was 9.1% (98/1077). Older age and non-traumatic fracture were two clinical risk factors for AVF. Neither radiological nor surgical feature was significantly correlated with AVF.

Fluorescence sensor based on optimized quantum yield manganese-carbon polymer dots and smartphone-integrated sensing platform for tetracycline detection.

The one-step synthesis of Mn-doped carbon quantum dots (Mn-CPDs) with a high quantum yield (QY = 45%) is reported using the microwave-assisted method. Subsequently, Mn-CPDs were successfully combined with Eu3+ ions to construct an Eu3+@Mn-CPDs fluorescence sensor. The presence of tetracycline (TC) induced a transition of fluorescence emission from blue (434 nm) to red (618 nm), and a robust linear relationship was observed between the ratio of F618 nm / F434 nm and the TC concentration (5 - 50 nmol/L), with a limit of detection (LOD) of 5.76 nmol/L. The underlying mechanism of Eu3+@Mn-CPDs and TC sensing is unveiled as a synergistic effect involving inner filter effect (IFE) and concurrent interactions. Notably, the smartphone-integrated sensing platform based on Eu3+@Mn-CPDs enables rapid and quantitative TC detection within a short time (< 30 s) by monitoring fluorescence color changes, achieving high-detection sensitivities (with a LOD of 6.18 nmol/L). This versatile and efficient sensing platform demonstrates its potential for the determination of TC concentrations in milk, honey, and tap water samples.

Widespread Occurrence and Transport of p-Phenylenediamines and Their Quinones in Sediments across Urban Rivers, Estuaries, Coasts, and Deep-Sea Regions.

p-Phenylenediamines (PPDs) are widely used as antioxidants in tire rubber, and their derived quinone transformation products (PPD-Qs) may pose a threat to marine ecosystems. A compelling example is N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD)-derived quinone, called 6PPD-Q, as the causal toxicant for stormwater-linked acute mortality toward coho salmon. However, the knowledge of the co-occurrences of PPDs and PPD-Qs and their transport from freshwater to oceanic waterbodies on a large geographical scale remains unknown. Herein, we performed the first large-scale survey of these chemicals in sediments across urban rivers, estuaries, coasts, and deep-sea regions. Our results demonstrated that seven PPDs and four PPD-Qs are ubiquitously present in riverine, estuarine, and coastal sediments, and most of them also occur in deep-sea sediments. The most dominant chemicals of concern were identified as 6PPD and 6PPD-Q. Total sedimentary concentrations of PPDs and PPD-Qs presented a clear spatial trend with decreasing levels from urban rivers (medians: 39.7 and 15.2 ng/g) to estuaries (14.0 and 5.85 ng/g) and then toward coasts (9.47 and 2.97 ng/g) and deep-sea regions (5.24 and 3.96 ng/g). Interestingly, spatial variation in the ratios of 6PPD to 6PPD-Q (R6PPD/6PPD-Q) also presented a clear decreasing trend. Our field measurements implied that riverine outflows of PPDs and PPD-Qs may be an important route to transport these tire rubber-derived chemicals to coastal and open oceans.

Preparation of PEI-modified nanoparticles by dopamine self-polymerization for efficient DNA delivery.

Achieving efficient and safe gene delivery is of great significance to promote the development of gene therapy. In this work, a polydopamine (PDA) layer was coated on the surface of Fe3 O4 nanoparticles (NPs) by dopamine (DA) self-polymerization, and then magnetic Fe3 O4 NPs were prepared by the Michael addition between amino groups in polyethyleneimine (PEI) and PDA. The prepared Fe3 O4 NPs (named Fe3 O4 @PDA@PEI) were characterized by Fourier transform infrared (FTIR), atomic force microscopy (AFM), and scanning electron microscopy (SEM). As an efficient and safe gene carrier, the potential of Fe3 O4 @PDA@PEI was evaluated by agarose gel electrophoresis, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, fluorescence microscopy, and flow cytometry. The results show that the Fe3 O4 @PDA@PEI NPs are stable hydrophilic NPs with a particle size of 50-150 nm. It can efficiently condense DNA at low N/P ratios and protect it from nuclease degradation. In addition, the Fe3 O4 @PDA@PEI NPs have higher safety than PEI. Further, the Fe3 O4 @PDA@PEI/DNA polyplexes could be effectively absorbed by cells and successfully transfected and exhibit higher cellular uptake and gene transfection efficiency than PEI/DNA polyplexes. The findings indicate that the Fe3 O4 @PDA@PEI NPs have the potential to be developed into a novel gene vector.

Mutations of PTCH1 gene in two pedigrees with bifid rib-basal cell nevus-jaw cyst syndrome. / 肋骨分叉-基底细胞痣-é¢Œéª¨å›Šè‚¿ç»¼åˆå¾ä¸¤å®¶ç³»åŸºå› åºåˆ—å˜å¼‚åˆ†æž.

Two male patients with bifid rib-basal cell nevus-jaw cyst syndrome (BCNS) were admitted to Department of Stomatology, the First Affiliated Hospital of Bengbu Medical College due to radiological findings of multiple low density shadows in the jaw. Clinical and imaging findings showed thoracic malformation, calcification of the tentorium cerebellum and falx cerebrum as well as widening of the orbital distance. Whole exon high-throughput sequencing was performed in two patients and their family members. The heterozygous mutations of c.C2541C>A(p.Y847X) and c.C1501C>T(p.Q501X) in PTCH1 gene were detected in both patients. Diagnosis of BCNS was confirmed. The heterozygous mutations of PTCH1 gene locus were also found in the mothers of the two probands. Proband 1 showed clinical manifestations of low intelligence, and heterozygous mutations of c.C2141T(p.P714L) and c.G3343A(p.V1115I) were detected in FANCD2 gene. Proband 2 had normal intelligence and no FANCD2 mutation. The fenestration decompression and curettage of jaw cyst were performed in both patients. Regular follow-up showed good bone growth at the original lesion, and no recurrence has been observed so far.

Computed tomography-guided cyanoacrylate injection for localization of multiple ipsilateral lung nodules.

OBJECTIVES: To retrospectively assess the clinical effectiveness of CT-guided cyanoacrylate localization for multiple ipsilateral small pulmonary nodules (SPNs) and to determine the independent predictors for pneumothorax. METHODS: In total, 81 patients with 169 lesions undergoing CT-guided cyanoacrylate localization for multiple ipsilateral SPNs between September 2016 and July 2020 were enrolled (group M). Another 284 patients who received single SPN localization during the same period served as the control group (group S). Propensity score analysis was performed to minimize selection bias. Possible independent predictors for pneumothorax were evaluated using multivariate logistic regression analysis. RESULTS: Multiple ipsilateral SPN localization was successfully performed in all 81 patients. The incidences of successful targeting during localization and surgery were 100% and 98.8%, respectively. Seventy-seven patients (95.1%) underwent the procedure on the day before the surgery. Propensity matching created 81 pairs of patients. There were no significant differences in the incidence of successful targeting during localization and surgery, localization-related pain score, and additional morphine use between the two groups. However, group M was associated with a significant longer localization procedural time (p < 0.001) and a higher incidence of pneumothorax (p < 0.001). In multivariate analysis, position change was significantly associated with a sevenfold increase in the risk for pneumothorax (p = 0.001). CONCLUSIONS: CT-guided cyanoacrylate injection for multiple ipsilateral SPN localization was safe and reliable, and allowed a flexible surgical schedule, despite a lengthy procedure and an increased incidence of pneumothorax. Avoiding position change may help to reduce the occurrence of pneumothorax. KEY POINTS: • Compared to single SPN localization, multiple ipsilateral SPN localization using cyanoacrylate injection achieved comparable safety, reliability, and comfort. • CT-guided cyanoacrylate localization for multiple ipsilateral SPNs allowed a flexible surgical schedule. • Position change was the only independent risk factor for pneumothorax during the multiple ipsilateral SPN localization.

Identification of Fluorescent Brighteners as Another Emerging Class of Abundant, Ubiquitous Pollutants in the Indoor Environment.

Fluorescent brighteners (FBs) are extensively used as important chemical additives in multiple industrial fields worldwide. The history of the use of global FBs spans over 60 years, but knowledge on their environmental occurrence and risks remains largely unknown. Here, we screened indoor dust and hand wipes from South China for a broad suite of 17 emerging FBs using a new comprehensive analytical method. All 17 FBs were detected in the indoor environment for the first time, most of them having been rarely investigated or never reported in prior environmental studies. Ionic FBs were found to be more abundant than nonionic ones. The median total concentrations of the 17 detectable FBs reached 11,000 ng/g in indoor dust and 2640 ng/m2 in hand wipes, comparable to or higher than those of well-known indoor pollutants. Human exposure assessment indicated that hand-to-mouth contact is a significant pathway for exposure to FBs, with a comparable contribution to that of dust ingestion. Most of the newly identified FBs are predicted to have persistent, bioaccumulative, or toxic properties. Our work demonstrates that FBs are another class of highly abundant, hazardous, and ubiquitous indoor pollutants that have been overlooked for decades and points to an emerging concern.

Microplastics in take-out food: Are we over taking it?

Take-out food has become increasingly prevalent due to the fast pace of people's life. However, few study has been done on microplastics in take-out food. Contacting with disposable plastic containers, take-out food may be contaminated with microplastics. In the present study, abundance and characteristics of microplastics in total of 146 take-out food samples including solid food samples and beverage samples (bubble tea and coffee) were determined and identified. The mean abundance of microplastics in take-out food was 639 items kg-1, with the highest value in rice and the lowest value in coffee. Fragments shape, transparent color and sizes ≤ 500 µm were the main characteristics of microplastics in those food, and polyethylene was the main polymer type. Our results indicated that microplastics in take-out food was influenced by food categories and cooking methods, as well as food packaging materials. Approximately 170-638 items of microplastics may be consumed by people who order take-out food 1-2 times weekly.

Effect of Extracellular Matrix Coating on Cancer Cell Membrane-Encapsulated Polyethyleneimine/DNA Complexes for Efficient and Targeted DNA Delivery In Vitro.

Polyethyleneimine (PEI) has a good spongy proton effect and is an excellent nonviral gene vector, but its high charge density leads to the instability and toxicity of PEI/DNA complexes. Cell membrane (CM) capsules provide a universal and natural solution for this problem. Here, CM-coated PEI/DNA capsules (CPDcs) were prepared through extrusion, and the extracellular matrix was coated on CPDcs (ECM-CPDcs) for improved targeting. The results showed that compared with PEI/DNA complexes, CPDcs had core-shell structures (PEI/DNA complexes were coated by a 6-10 nm layer), lower cytotoxicity, and obvious homologous targeting. The internalization and transfection efficiency of 293T-CM-coated PEI70k/DNA capsules (293T-CP70Dcs) were 91.8 and 74.5%, respectively, which were higher than those of PEI70k/DNA complexes. Then, the internalization and transfection efficiency of 293T-CP70Dcs were further improved by ECM coating, which were 94.7 and 78.9%, respectively. Then, the internalization and transfection efficiency of 293T-CP70Dcs were further improved by ECM coating, which were 94.7 and 78.9%, respectively. Moreover, the homologous targeting of various CPDcs was improved by ECM coating, and other CPDcs also showed similar effects as 293T-CP70Dcs after ECM coating. These findings suggest that tumor-targeted CPDcs may have considerable advantages in gene delivery.

Rate-Limited Reaction in TEMPO/Laccase/O2 Oxidation of Cellulose.

The environment-friendly oxidation of cellulose by the 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO)/laccase/O2 system is an alternative route with huge potential to prepare cellulose nanofibers. It is found that the concentration of TEMPO significantly affects the oxidation efficiency. An effective method for improving the oxidation effect is to increase the TEMPO concentration and prolong the oxidation time. To clarify the rate-limited step of TEMPO/laccase/O2 oxidation of cellulose, the academically accepted oxidation process is divided into individual pathways. A series of experiments is conducted with laccase and the three forms of organocatalyst (TEMPO, oxoammonium (TEMPO+), and hydroxylamine (TEMPOH)) to simulate individual reactions and calculate the reaction rates. The concentrations of TEMPO and oxoammonium are monitored by EPR spectroscopy. The oxidation rate of TEMPO by laccase varies at different pH conditions, and laccase activity is much higher at pH 4.5. Other reactions without laccase involved express a higher reaction rate when the pH value increased. TEMPO is mainly regenerated through a comproportionation reaction between oxoammonium and hydroxylamine. The acceleration of TEMPO regeneration by laccase is not obvious. The results indicate that the rate-limited reaction in TEMPO/laccase/O2 oxidation is cellulose oxidation by TEMPO+.

Preparation of Silk Nanowhisker-Composited Amphoteric Cellulose/Chitin Nanofiber Membranes.

Native biopolymer nanofibers (cellulose, chitin, and silk nanofiber) are one of the most important contributors to the outstanding functions and mechanical properties of natural materials. To enhance the mechanical performance, A great deal of top-down routes have been reported to prepare biopolymers nanofibers/nanowhiskers that retaining their nanostructures. Compared with advances in cellulose and chitin nanofibers/nanowhiskers, it remains difficult for direct downsizing the natural silk fibers into silk nanofibers/nanowhiskers (SNFs/SNWs) because of their high crystallinity and sophisticated structures. In this work, environmentally friendly and recyclable deep eutectic solvents (DESs) were used to direct pretreat and downsize natural silks into silk nanowhiskers with high yield. SNWs with similar diameter (3.1-22 nm for OA/ChCl DES treated SNWs, 2.7-20 nm for CA/ChCl DES treated SNWs) and contour length (329 ± 140 nm for OA/ChCl DES treated SNWs, 365 ± 200 nm for CA/ChCl DES treated SNWs) to individual nanofibers in natural silk fibers were obtained. In addition, the separated DES with a recovery yield of at least 92% could be reused four times to produce SNWs, indicating the possibility of DESs as green solvents for sustainable biopolymer nanomaterial extraction. Based on the inherent amphoteric properties of SNWs, multicompatibility was explored to facilely composite SNWs with various polymers for preparation of coextruded membranes with enhanced performance and endowed the composites with protein-endowed double adsorption properties. Overall, this work demonstrated that the DES pretreatment process is promising for green and low-cost biopolymer nanomaterial extraction and that the SNWs prepared via DES have good prospects as nanoscale materials in the environmental field and in development of smart biomaterials and drug delivery in biomedicine.

Simultaneous detection of site-specific histone methylations and acetylation assisted by single template oriented molecularly imprinted polymers.

Histone post-translational modification (PTM) is a marker for gene transcription and is involved in a range of cancers, such as breast cancer. Most importantly, different modifications of a specific site (e.g., mono-, di- and tri-methylations and acetylation at a lysine residue) are individually enriched in particular regions of the genome, indicating that they may serve distinct functions. How these patterns are built and whether downstream events are dependent on the precise site-specific modification status are still poorly understood. One of the prerequisites is to obtain quantitative information on individual modification forms. Currently, the low abundance of these forms creates a great challenge. In this study, a targeted proteomics assay based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) coupled with single template oriented molecularly imprinted polymers (MIPs) was developed to attempt to simultaneously quantify site-specific histone mono-, di- and tri-methylated and acetylated forms. Surrogate peptides, including an unmodified one, were selected as targets in both MIP enrichment and subsequent LC-MS/MS detection. As a consequence, a limit of quantification (LOQ) of ∼0.5 nM was achieved, which was 10-fold more sensitive than without MIPs and much more sensitive than mass spectrometry involving a scanning mode. Finally, the assay was employed to quantitatively analyze the H3K79, H3K122 and H4K31 modification status in human breast cell lines.

Plastics Are an Insignificant Carrier of Riverine Organic Pollutants to the Coastal Oceans.

Global rivers act as a dominant transport pathway for land-based plastic debris to the marine environment. Organic pollutants (OPs) affiliated with riverine plastics can also enter the global oceans, but their amounts remain unknown. Microplastic (MP) samples were collected in a one-year sampling event from the surface water of the eight main riverine outlets in the Pearl River Delta (PRD), China, and analyzed for OPs affiliated with MPs, including 16 polycyclic aromatic hydrocarbons (PAHs), eight polybrominated diphenyl ethers (PBDEs), and 14 polychlorinated biphenyls (PCBs). The mean concentrations of MP-affiliated ∑16PAH, ∑8PBDE, and ∑14PCB were 2010 (range: 25-40,100), 412 (range: 0.84-14,800), and 67.7 (range: 1.86-456) ng g-1, respectively. Based on these and previous results, the annual riverine outflows of MP-affiliated OPs were 148, 83, and 8.03 g for ∑16PAH, ∑8PBDE, and ∑14PCB, respectively. Assuming that plastic debris of different sizes contained the same concentrations of the target pollutants as MPs, the mean riverine outflows of plastic-bound ∑16PAH, ∑8PBDE, and ∑14PCB were 6.75, 3.77, and 0.37 kg year-1, respectively, which were insignificant compared with the riverine outflows of OPs through riverine water discharge (up to hundred tons per year). Apparently, plastics are an insignificant carrier of riverine OPs to the coastal oceans.

Global Riverine Plastic Outflows.

Global marine plastic pollution, which is derived mainly from the input of vast amounts of land-based plastic waste, has drawn increasing public attention. Riverine plastic outflows estimated using models based on the concept of mismanaged plastic waste (MPW) are substantially greater than reported field measurements. Herein, we formulate a robust model using the Human Development Index (HDI) as the main predictor, and the modeled riverine plastic outflows are calibrated and validated by available field data. A strong correlation is achieved between model estimates and field measurements, with a regression coefficient of r2 = 0.9. The model estimates that the global plastic outflows from 1518 main rivers were in the range of 57,000-265,000 (median: 134,000) MT year-1 in 2018, which were approximately one-tenth of the estimates by MPW-based models. With increased plastic production and human development, the global riverine plastic outflow is projected to peak in 2028 in a modeled trajectory of 2010-2050. The HDI is a better indicator than MPW to estimate global riverine plastic outflows, and plastic pollution can be effectively assessed and contained during human development processes. The much lower global riverine plastic outflows should substantially ease the public's concern about marine plastic pollution and financial pressure for remediation.

Low-Cost Cellulase-Hemicellulase Mixture Secreted by Trichoderma harzianum EM0925 with Complete Saccharification Efficacy of Lignocellulose.

Fermentable sugars are important intermediate products in the conversion of lignocellulosic biomass to biofuels and other value-added bio-products. The main bottlenecks limiting the production of fermentable sugars from lignocellulosic biomass are the high cost and the low saccharification efficiency of degradation enzymes. Herein, we report the secretome of Trichoderma harzianum EM0925 under induction of lignocellulose. Numerously and quantitatively balanced cellulases and hemicellulases, especially high levels of glycosidases, could be secreted by T. harzianum EM0925. Compared with the commercial enzyme preparations, the T. harzianum EM0925 enzyme cocktail presented significantly higher lignocellulolytic enzyme activities and hydrolysis efficiency against lignocellulosic biomass. Moreover, 100% yields of glucose and xylose were obtained simultaneously from ultrafine grinding and alkali pretreated corn stover. These findings demonstrate a natural cellulases and hemicellulases mixture for complete conversion of biomass polysaccharide, suggesting T. harzianum EM0925 enzymes have great potential for industrial applications.

Riverine Microplastic Pollution in the Pearl River Delta, China: Are Modeled Estimates Accurate?

Plastic pollution has caused increasing global concern. Currently, model estimates of the riverine plastic inputs to the global oceans based on the concept of Mismanaged Plastic Waste (MPW) varied substantially, and no field measurements of riverine inputs were available. We conducted sampling at the eight major river outlets of the Pearl River Delta, South China with rapid economic growth and urbanization to provide field measured data for fine-tuning modeling results. Floating microplastics (MPs) were collected with a Manta net (mesh size of 0.33 mm) five times during 2018. Microplastic particles (0.3-5.0 mm) widely occurred in all sampling sites. The number and mass concentrations of MPs were in the ranges of 0.005-0.7 particles m-3 and 0.004-1.28 mg m-3 and were positively correlated with water discharges. The annual riverine input of MPs from the Pearl River Delta was estimated at 39 billion particles or 66 tons, which converts to 2400-3800 tons of plastic debris based on calculations described in Text S2. These values were substantially below the MPW-based model estimates (91,000-170,000 tons). The large difference between measured and modeling results may have derived from the large uncertainty in the MPW values assigned to the world's countries/regions.

pH- and Amylase-Responsive Carboxymethyl Starch/Poly(2-isobutyl-acrylic acid) Hybrid Microgels as Effective Enteric Carriers for Oral Insulin Delivery.

Oral delivery of insulin has the potential to revolutionize diabetes care since it is regarded as a noninvasive therapeutic approach without the side effects caused by frequent subcutaneous injection. However, the insulin delivery efficiency through oral route was still limited, likely due to the chemical, enzymatic and absorption barriers. In this study, a novel type of pH- and amylase-responsive microgels as an insulin drug carrier for oral administration was developed to improve the drug delivery efficiency. The microgels were prepared via aqueous dispersion copolymerization of acrylate- grafted-carboxymethyl starch (CMS- g-AA) and 2-isobutyl-acrylic acid ( iBAA). The resulting hybrid microgels with the P iBAA contents of 13.6-45.3 wt% exhibited sharp pH-sensitivity, which was revealed by the changes in particle size of the microgels and the transmittance of the microgel aqueous solution. The accelerated decomposition of the CMS-containing microgels in response to amylase was demonstrated by chromogenic reaction and morphology change. Insulin was loaded into the microgels by swelling-diffusion method, and the insulin release from the insulin-loaded microgels in vitro was found to be triggered by pH change and addition of amylase, which was highly dependent on the microgel component. Cytotoxicity assay was performed to show the good biocompatibility of the microgels. In addition, the tests of cellular uptake by Caco-2 cells and transmembrane transport through the Caco-2 cell monolayers were carried out to confirm the intestinal absorption ability of the insulin-loaded microgels. Finally, the oral administration of insulin-loaded microgels to STZ-induced diabetic rats led to a continuous decline in the fasting blood glucose level within 2 to 4 h, and the hypoglycemic effect maintained over 6 h in vivo. The relative pharmacological availability of the insulin-loaded microgels was enhanced 23-38 times compared to free-form insulin solution through oral route. Therefore, the novel starch-based microgels may have potential as an efficient platform for oral insulin delivery.

Cellulose Nanofibers Prepared Using the TEMPO/Laccase/O2 System.

The 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)/laccase/O2 system was used to prepare cellulose nanofibers from wood cellulose without requiring any chlorine-containing oxidant. Laccase was degraded by oxidized TEMPO (TEMPO+) formed by laccase-mediated oxidation with O2, which competed with the oxidation of wood cellulose. Thus, large amounts of laccase and TEMPO and a long reaction time were needed to introduce ∼0.6 mmol g-1 of C6-carboxylate groups onto wood cellulose. The TEMPO/laccase/O2 system underwent one-way reaction from TEMPO to reduced TEMPO through TEMPO+. When the oxidation was applied again to the oxidized wood cellulose following isolation and purification, the C6-carboxylate groups increased to ∼1.1 mmol g-1, which was sufficient to convert the sample to cellulose nanofibers by sonication in water. However, the higher the carboxylate content of the oxidized celluloses, the lower their degree of polymerization.

Impact of Polymer Colonization on the Fate of Organic Contaminants in Sediment.

Plastic pellets and microbes are important constitutes in sediment, but the significance of microbes colonizing on plastic pellets to the environmental fate and transport of organic contaminants has not been adequately recognized and assessed. To address this issue, low-density polyethylene (LDPE), polyoxymethylene (POM) and polypropylene (PP) slices were preloaded with dichlorodiphenyltrichloroethanes (DDTs), polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) and incubated in abiotic and biotic sediment microcosms. Images from scanning electron microscope, Lysogeny Broth agar plates and confocal laser scanning microscope indicated that all polymer slices incubated in biotic sediments were colonized by microorganisms, particularly the LDPE slices. The occurrence of biofilms induced higher dissipation rates of DDTs and PAHs from the LDPE slice surfaces incubated in the biotic sediments than in the abiotic sediments. Plastic colonization on LDPE slice surfaces enhanced the biotransformation of DDT and some PAHs in both marine and river sediments, but had little impact on PCBs. By comparison, PP and POM with unique properties were shown to exert different impacts on the physical and microbial activities as compared to LDPE. These results clearly demonstrated that the significance of polymer surface affiliated microbes to the environmental fate and behavior of organic contaminants should be recognized.