A dual-channel indicator of fish spoilage based on a D-π-A luminogen serving as a smart label for intelligent food packaging.

Advances in food monitoring benefit tremendously from the naked-eye observation and device-miniaturization of colorimetric and fluorometric methods. Intelligent food packaging, containing a built-in sensor inside food bags, is capable of real-time monitoring of food quality by visibly discernible out-put signals, which effectively ensures food safety. We synthesized a donor-π-acceptor (D-π-A) compound DPABA, and disclosed its fluorescence response to amines. According to quantum chemical calculations, DPABA is apt to D-A coupling in aggregated state, causing the formation of exciplex/excimer together with intermolecular charge/energy transfer to the disadvantage of light emission; while the evasion of amine vapors would decouple the intermolecular D-A interactions to induce stronger emission with shorter wavelength. Utilizing the amine vapor generated by fish, DPABA can serve as an indicator for freshness monitoring. To create an intelligent food package, the compound was made into cellulose film, which was further cut into smart labels to be encapsulated into food bags. The as-prepared smart label exhibits red color under ambient light and glows weak red emission under UV light, while it turns into faint yellow color in response to putrid fish, and its emission changes to bright cyan. The output signals can be accurately recorded by instrument, and detected by naked eye, suggesting high signal contrast. In addition, the smart label exhibits different changing scope in response to different degree of freshness, showing high potential for in-field detection.

Atomic Layer Deposition of a Silver Nanolayer on Advanced Titanium Orthopedic Implants Inhibits Bacterial Colonization and Supports Vascularized de Novo Bone Ingrowth.

Joint replacement surgery is associated with significant morbidity and mortality following infection with either methicillin-resistant Staphylococcus aureus (MRSA) or Staphylococcus epidermidis. These organisms have strong biofilm-forming capability in deep wounds and on prosthetic surfaces, with 103 -104 microbes resulting in clinically significant infections. To inhibit biofilm formation, we developed 3D titanium structures using selective laser melting and then coated them with a silver nanolayer using atomic layer deposition. On bare titanium scaffolds, S. epidermidis growth was slow but on silver-coated implants there were significant further reductions in both bacterial recovery (p < 0.0001) and biofilm formation (p < 0.001). MRSA growth was similarly slow on bare titanium scaffolds and not further affected by silver coating. Ultrastructural examination and viability assays using either human bone or endothelial cells, demonstrated strong adherence and growth on titanium-only or silver-coated implants. Histological, X-ray computed microtomographic, and ultrastructural analyses revealed that silver-coated titanium scaffolds implanted into 2.5 mm defects in rat tibia promoted robust vascularization and conspicuous bone ingrowth. We conclude that nanolayer silver of titanium implants significantly reduces pathogenic biofilm formation in vitro, facilitates vascularization and osseointegration in vivo making this a promising technique for clinical orthopedic applications.

Highly degradable porous melt-derived bioactive glass foam scaffolds for bone regeneration.

A challenge in using bioactive melt-derived glass in bone regeneration is to produce scaffolds with interconnected pores while maintaining the amorphous nature of the glass and its associated bioactivity. Here we introduce a method for creating porous melt-derived bioactive glass foam scaffolds with low silica content and report in vitro and preliminary in vivo data. The gel-cast foaming process was adapted, employing temperature controlled gelation of gelatin, rather than the in situ acrylic polymerisation used previously. To form a 3D construct from melt derived glasses, particles must be fused via thermal processing, termed sintering. The original Bioglass® 45S5 composition crystallises upon sintering, altering its bioactivity, due to the temperature difference between the glass transition temperature and the crystallisation onset being small. Here, we optimised and compared scaffolds from three glass compositions, ICIE16, PSrBG and 13-93, which were selected due to their widened sintering windows. Amorphous scaffolds with modal pore interconnect diameters between 100-150µm and porosities of 75% had compressive strengths of 3.4±0.3MPa, 8.4±0.8MPa and 15.3±1.8MPa, for ICIE16, PSrBG and 13-93 respectively. These porosities and compressive strength values are within the range of cancellous bone, and greater than previously reported foamed scaffolds. Dental pulp stem cells attached to the scaffold surfaces during in vitro culture and were viable. In vivo, the scaffolds were found to regenerate bone in a rabbit model according to X-ray micro tomography imaging. STATEMENT OF SIGNIFICANCE: This manuscript describes a new method for making scaffolds from bioactive glasses using highly bioactive glass compositions. The glass compositions have lower silica content that those that have been previously made into amorphous scaffolds and they have been designed to have similar network connectivity to that of the original (and commercially used) 45S5 Bioglass. The aim was to match Bioglass' bioactivity. The scaffolds retain the amorphous nature of bioactive glass while having an open pore structure and compressive strength similar to porous bone (the original 45S5 Bioglass crystallises during sintering, which can cause reduced bioactivity or instability). The new scaffolds showed unexpectedly rapid bone regeneration in a rabbit model.

Biotransformation of Silver Released from Nanoparticle Coated Titanium Implants Revealed in Regenerating Bone.

Antimicrobial silver nanoparticle coatings have attracted interest for reducing prosthetic joint infection. However, few studies report in vivo investigations of the biotransformation of silver nanoparticles within the regenerating tissue and its impact on bone formation. We present a longitudinal investigation of the osseointegration of silver nanoparticle-coated additive manufactured titanium implants in rat tibial defects. Correlative imaging at different time points using nanoscale secondary ion mass spectrometry, transmission electron microscopy (TEM), histomorphometry, and 3D X-ray microcomputed tomography provided quantitative insight from the nano- to macroscales. The quality and quantity of newly formed bone is comparable between the uncoated and silver coated implants. The newly formed bone demonstrates a trabecular morphology with bone being located at the implant surface, and at a distance, at two weeks. Nanoscale elemental mapping of the bone-implant interface showed that silver was present primarily in the osseous tissue and colocalized with sulfur. TEM revealed silver sulfide nanoparticles in the newly regenerated bone, presenting strong evidence that the previously in vitro observed biotransformation of silver to silver sulfide occurs in vivo.

Elucidation of differential mineralisation on native and regenerated silk matrices.

Bone mineralisation is a well-orchestrated procedure triggered by a protein-based template inducing the nucleation of hydroxyapatite (HA) nanocrystals on the matrix. In an attempt to fabricate superior nanocomposites from silk fibroin, textile braided structures made of natively spun fibres of Bombyx mori silkworm were compared against regenerated fibroin (lyophilized and films) underpinning the influence of intrinsic properties of fibroin matrices on HA nucleation. We found that native braids could bind Ca(2+) ions through electrostatic attraction, which initiated the nucleation and deposition of HA, as evidenced by discrete shift in amide peaks via ATR-FTIR. This phenomenon also suggests the involvement of amide linkages in promoting HA nucleation on fibroin. Moreover, CaCl2-SBF immersion of native braids resulted in preferential growth of HA along the c-axis, forming needle-like nanocrystals and possessing Ca/P ratio comparable to commercial HA. Though regenerated lyophilized matrix also witnessed prominent peak shift in amide linkages, HA growth was restricted to (211) plane only, albeit at a significantly lower intensity than braids. Regenerated films, on the other hand, provided no crystallographic evidence of HA deposition within 7days of SBF immersion. The present work sheds light on the primary fibroin structure of B. mori which probably plays a crucial role in regulating template-induced biomineralisation on the matrix. We also found that intrinsic material properties such as surface roughness, geometry, specific surface area, tortuosity and secondary conformation exert influence in modulating the extent of mineralisation. Thus our work generates useful insights and warrants future studies to further investigate the potential of bone mimetic, silk/mineral nanocomposite matrices for orthopaedic applications.

Remarkable enhancement of charge carrier mobility of conjugated polymer field-effect transistors upon incorporating an ionic additive.

Organic semiconductors with high charge carrier mobilities are crucial for flexible electronic applications. Apart from designing new conjugated frameworks, different strategies have been explored to increase charge carrier mobilities. We report a new and simple approach to enhancing the charge carrier mobility of DPP-thieno[3,2-b]thiophene-conjugated polymer by incorporating an ionic additive, tetramethylammonium iodide, without extra treatments into the polymer. The resulting thin films exhibit a very high hole mobility, which is higher by a factor of 24 than that of thin films without the ionic additive under the same conditions. On the basis of spectroscopic grazing incidence wide-angle x-ray scattering and atomic force microscopy studies as well as theoretical calculations, the remarkable enhancement of charge mobility upon addition of tetramethylammonium iodide is attributed primarily to an inhibition of the torsion of the alkyl side chains by the presence of the ionic species, facilitating a more ordered lamellar packing of the alkyl side chains and interchain π-π interactions.

[The effect of lead exposure in utero on the teeth eruption and enamel development of rat offspring.].

OBJECTIVE: To investigate the effects of lead exposure at different levels in utero on the teeth eruption and enamel development of rat offsprings. METHODS: 27 pregnant SD rats were divided into three groups randomly: high level lead group (HLG), low level lead group (LLG) and control group with nine rats in each group. The three groups from the gestation day to the end of the gestation were given either deionized water in control group or deionized water containing 200 mg/L Pb2+ as lead acetate through drinking method in high level lead experimental group and 50 mg/L Pb2+ as lead acetate through drinking method in low level lead experimental group. The incisors of newborn rats were marked at the level of the gingival papilla on the 26th day after birth. On the 36th day, the incisors of newborn rats were marked again at the same level. Then the rat offsprings were killed and their blood was collected for lead analysis. The mandible incisors of rat offspring were separated and the content of Pb in incisors was determined by using a graphite furnace atomic absorption spectrometric method. The teeth of rat offspring were observed and the distance between two marks were measured by means of stereomicroscope. The ratio of calcium to phosphate of enamel of rat offspring was compared by electron probe microanalyses. RESULTS: The level of blood lead in 200 mg/L, 50 mg/L treated rat offspring groups was higher than that in control group. The tooth lead of 200 mg/L, 50 mg/L treated rat offspring groups [(77.3 +/- 6.3), (27.8 +/- 4.5) microg/g] were higher than the control [(6.6 +/- 0.8) microg/g, P < 0.01]. Compared with the control group, the teeth of lead exposure experimental groups were smaller and severity of attrition was obvious and pulpal perforations were often observed. These appearances was more distinct in rats of high level lead experimental group. The incisors of lead-treated rat offspring erupted [(0.25 +/- 0.08), (0.30 +/- 0.09) mm/d] more slowly than control ones [(0.39 +/- 0.09) mm/d, P < 0.01]. The ratio of calcium to phosphate (Ca/P) decreased with the increase of lead exposure. It was found that Ca/P in lead exposure experimental groups (1.68 +/- 0.54), (1.37 +/- 0.47) was significantly lower than that in the control group (2.14 +/- 0.33). CONCLUSION: Lead exposure in utero affects the normal eruption of teeth and enamel formation and the degree was related with the lead exposure level.

[Effects of lactational dioxin exposure to development of alveolar bone in SD rat offspring].

OBJECTIVE: To study the influence of lactational dioxin exposure (2, 3, 7, 8-tetrachlorodibenzo-p-dixon, TCDD) on development of alveolar bone in SD rat offspring. METHODS: The rats of TCDD exposure group and control group were sacrificed and the alveolar bone with molars of PD60 rats in the two groups were embedded in resin. The sections were observed by fluorescent microscope. The alveolar bone formation was evaluated by histological examination, tetracycline fluorescence marker and quantitative histomorphometry. The indices of quantitative histomorphometry were compared. RESULTS: The trabecular structure of alveolar bone was looser in TCDD exposure group than in the control group. The tetracycline fluorescence markers were more disorganized in TCDD group. The indices of quantitative histomorphometry of alveolar bone between two groups showed significantly different. CONCLUSIONS: Lactational 2,3,7,8-TCDD exposure decreased the quality and quantity of alveolar bone in SD rat offspring. It is suggested that dioxins exposure may interrupt the spatial configuration.

[Association of vitamin D receptor gene polymorphisms with the susceptibility to chronic periodontitis of Han nationality].

OBJECTIVE: To investigate association of vitamin D receptor (VDR) gene polymorphisms with the susceptibility to chronic periodontitis (CP) of Han Nationality. METHODS: Buccal swabs from 166 patients with severe, moderate and mild CP respectively and 80 matched control individuals were collected. DNA was extracted from these buccal swabs using Chelex-100 method. VDR BsmI, ApaI, TaqI were tested with polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The distribution of the genotypes and allele frequencies in the patient and control groups were analyzed. RESULTS: The frequency of VDR ApaI allele A was significantly higher among patients with CP than controls. Frequencies of VDR ApaI allele A were significantly higher in severe CP patients than in moderate CP and mild CP respectively. There was no significant difference in the genotype distribution or the allele frequencies of VDR BsmI and TaqI between the controls and CP patients. CONCLUSIONS: These data indicate that VDR ApaI allele A may be related to the susceptibility to CP in Han Nationality.