Application of surface-modified functional packaging in food storage: A comprehensive review.

Innovations in food packaging systems could meet the evolving needs of the market; emerging concepts of non-migrating technologies reduce the negative migration of preservatives from packaging materials, extend shelf life, and improve food quality and safety. Non-migratory packaging activates the surface of inert materials through pretreatment to generate different active groups. The preservative is covalently grafted with the resin of the pretreated packaging substrate through the graft polymerization of the monomer and the coupling reaction of the polymer chain. The covalent link not only provides the required surface properties of the material for a long time but also retains the inherent properties of the polymer. This technique is applied to the processing for durable, stable, and easily controllable packaging widely. This article reviews the principles of various techniques for packaging materials, surface graft modification, and performance characterization of materials after grafting modification. Potential applications in the food industry and future research trends are also discussed.

Aggregation and Binding-Directed FRET Modulation of Conjugated Polymer Materials for Selective and Point-of-Care Monitoring of Serum Albumins.

Nonspecific interactions of conjugated polymers (CPs) with various proteins prove to be a major impediment for researchers when designing a suitable CP-based probe for the amplified and selective recognition of particular proteins in complex body fluids. Herein, a new strategy is presented for the precise and specific monitoring of clinically important serum albumin (SA) proteins at the nanomolar level using fluorescence resonance energy transfer (FRET)-modulated CP-surfactant ensembles as superior sensing materials. In brief, the newly designed color-tunable CP PF-DBT-Im undergoes intense aggregation with the surfactant sodium dodecyl sulfate (SDS), enabling drastic change in the emission color from violet to deep red due to intermolecular FRET. The emission of PF-DBT-Im/SDS ensembles then changed from deep red to magenta specifically on addition of SAs owing to the exclusive reverse FRET facilitated by synergistic effects of electrostatic interactions, hydrophobic forces, and the comparatively high intrinsic quantum yield of SAs. Interestingly, PF-DBT-Im itself could not differentiate SAs from other proteins, demonstrating the superiority of the PF-DBT-Im/SDS self-assembly over PF-DBT-Im. Finally, an affordable smartphone-integrated point-of-care (PoC) device is also fabricated as a proof-of-concept for the on-site and rapid monitoring of SAs, validating the potential of the system in long-term clinical applications.

Conjugated polymer nanoparticles and their nanohybrids as smart photoluminescent and photoresponsive material for biosensing, imaging, and theranostics.

The emergence of conjugated polymers (CPs) has provided a pathway to attain smart multifunctional conjugated polymer nanoparticles (CPNs) with enhanced properties and diverse applications. CPNs based on π-extended CPs exhibit high fluorescence brightness, low cytotoxicity, excellent photostability, reactive oxygen species (ROS) generation ability, high photothermal conversion efficiency (PCE), etc. which endorse them as an excellent theranostic tool. Furthermore, the unique light-harvesting and energy transfer properties of CPNs enables their transformation into smart functional nanohybrids with augmented performance. Owing to such numerous features, simple preparation method and an easy separation process, the CPNs and their hybrids have been constantly rising as a frontrunner in the domain of medicine and much work has been done in the respective research area. This review summarizes the recent progress that has been made in the field of CPNs for biological and biomedical applications with special emphasis on biosensing, imaging, and theranostics. Following an introduction into the field, a first large section provides overview of the conventional as well as recently established synthetic methods for various types of CPNs. Then, the CPNs-based fluorometric assays for biomolecules based on different detection strategies have been described. Later on, examples of CPNs-based probes for imaging, both in vitro and in vivo using cancer cells and animal models have been explored. The next section highlighted the vital theranostic applications of CPNs and corresponding nanohybrids, mainly via imaging-guided photodynamic therapy (PDT), photothermal therapy (PTT) and drug delivery. The last section summarizes the current challenges and gives an outlook on the potential future trends on CPNs as advanced healthcare material.

Wire-drawing process with graphite lubricant as an industrializable approach to prepare graphite coated stainless-steel anode for bioelectrochemical systems.

Carbon coated stainless-steel (SS) electrode has been suggested to be a powerful composite electrode with high conductivity, excellent biocompatibility and good mechanical strength, which is promising for scaling up the bioelectrochemical systems (BESs). However, the already reported carbon coating methods were independent on the production of SS material. Additional steps and investment of equipment for carbon coating are costly, and the industrialization of these carbon coating processes remains challenging. In this study, we report an industrializable carbon coating approach that was embedded into the production line of the SS wire, which was realized through a wire-drawing process with graphite emulsion as the lubricant and carbon source. We found the slide of SS wire through the dies was essential for the graphite coating in terms of loading amount and stability. When the graphite coated SS wire was prepared as the anode and operated in a BESs, the current density reached 1.761 ± 0.231 mA cm-2, which was 20 times higher than that without graphite coating. Biomass analysis was then conducted, confirming the superior bioelectrochemical performance was attributed to the improvement of biocompatibility by the graphite coating layer. Furthermore, graphite coating by the wire-drawing process was systematically compared with the existing methods, which showed a comparable or even better bioelectrochemical performance but with extremely low cost (0.036 $·m-2) and seconds level of the time consumption. Overall, this study offers a cost-effective and industrializable approach to preparing graphite coated SS electrode, which may open up great opportunities to promote the development of BESs at large scale.

Borate Inorganic Cross-Linked Durable Graphene Oxide Membrane Preparation and Membrane Fouling Control.

Graphene oxide (GO) membranes have the potential to be next-generation membranes. However, the GO layer easily swells in water and risks shedding during the long-term filtration. Organic GO interlayer organic cross-linking agent was not resistant to oxidation, which limits the application scope of GO membrane. In this study, an inorganic cross-linked GO membrane was prepared via the reaction of sodium tetraborate and GO hydroxyl groups, and a -B-O-C- cross-linking bond was detected by X-ray photoelectron spectroscopy (XPS). Additionally, a new atomic force microscope scratch method to evaluate the cross-linking force of a nanoscale GO layer was proposed. It showed that the critical destructive load of the inorganic cross-linked GO membrane increased from 8 to 80 nN, which was a 10-fold increase from that of the nonlinked sample. During the NaOH/sodium dodecyl sulfate (SDS) destructive wash tests, morphology, flux and retention rate of inorganic cross-linked GO remained stable while the comparative membranes showed significant destruction. At the same time, based on the better oxidation resistance, organic membrane fouling was effectively controlled by the introduction of trace ·OH radicals. This study provides a new perspective for GO membrane preparation, interlayer cross-linking force testing and membrane fouling control.

Effects of Different Carbon Sources on Enzyme Production and Ultrastructure of Cellulosimicrobium cellulans.

The secretomes of the strain Cellulosimicrobium cellulans F16 grown on different carbon sources were analyzed by zymography, and the subcellular surface structures were extensively studied by electron microscope. The exo-cellulase and xylanase systems were sparse when cells were grown on soluble oligosaccharides, but were significantly increased when grown on complex and water-insoluble polysaccharides, such as Avicel, corn cob, and birchwood xylan. The cellulosome-like protuberant structures were clearly observed on the cell surfaces of strain F16 grown on cellulose, with diameters of 15-20 nm. Fibrous structures that connected the adjacent cells can be seen under microscope. Moreover, protuberances that adsorbed the cell to cellulose were also observed. As the adhesion of Cellulosimicrobium cellulans cells onto cellulose surfaces occurs via thick bacterial curdlan-type exopolysaccharides (EPS), such surface layer is potentially important in the digestion of insoluble substrates such as cellulose or hemicellulose, and the previously reported xylanosomes are part of such complex glycocalyx layer on the surface of the bacterial cell.

Development and In Vitro Evaluation of Linear PEI-Shelled Heparin/Berberine Nanoparticles in Human Osteosarcoma U-2 OS Cells.

Berberine (BBR), a natural isoquinoline alkaloid derived from Chinese herbs, exerts many biological effects, including antiviral, antimicrobial, antidiarrhea, anti-inflammatory, and antitumor effects. In this study, a novel berberine nanoparticle (NP) consisting of heparin (HP) and BBR with or without being shelled with linear polyethyleneimine (LPEI) was developed to enhance its antitumor activity on osteosarcoma U-2 OS cells. With varying ratios of HP to BBR, HP/BBR NPs had a size ranging from 218.4 ± 3.9 to 282.0 ± 5.1 nm and zeta potential from -35.7 ± 0.4 to -51.9 ± 1.8 mV. After shelling with LPEI, the resultant NPs (HP/BBR/LPEI) possessed a size ranging from 226.3 ± 3.0 to 405.7 ± 85.2 nm and zeta potential from -46.5 ± 0.3 to -35.6 ± 0.5 mV; the encapsulation rate of BBR was close to 80%. The release profiles of both NPs were revealed to be slower than that of BBR solution. Results also showed that BBR and its two derived NPs reduced the viability of U-2 OS cells, and BBR NPs increased the cellular uptake of BBR. Cells were arrested at the G1 phase when treated individually with BBR and the two NPs (HP/BBR and HP/BBR/LPEI) and DNA condensation was induced. In addition, BBR and BBR NPs reduced the expression of mouse double minute 2 homolog (MDM2) but increased that of p53, and BBR NPs enhanced apoptotic effects. In short, heparin-based nanoparticles could be potential carriers for osteosarcoma treatment.

Selective adsorption of protein by a high-efficiency Cu(2+) -cooperated magnetic imprinted nanomaterial.

We report a core-shell magnetic molecularly imprinted polymer with high affinity through a facile sol-gel method for the selective adsorption of bovine hemoglobin from real bovine blood. Copper ions grafted on the surface of the matrix could immobilize template protein through chelation, which greatly enhances the orderliness of imprinted cavities and affinity of polymers. The obtained products exhibit a desired level of magnetic susceptibility, resulting in the highly efficient adsorption process. The results of adsorption experiments show that the saturation adsorption capacity of imprinted products could reach 116.3 mg/g within 30 min. Meanwhile, the specific binding experiment demonstrates the high selectivity of polymers for bovine hemoglobin. Furthermore, satisfactory reusability is demonstrated by ten adsorption-desorption cycles with no obvious deterioration in binding capacity. Electrophoretic analysis suggests the polymer could be used successfully in separation and enrichment of bovine hemoglobin from the bovine blood sample, which exhibits potential application in pretreatment of proteomics.

Preparation of magnetic glycoprotein-imprinted nanoparticles with dendritic polyethyleneimine as a monomer for the specific recognition of ovalbumin from egg white.

Glycoproteins are crucial in massive physiological events and clinical application. It is necessary to prepare new materials to isolate the specific glycoprotein. New and simple core-shell molecularly imprinted polymers were prepared by surface imprinting. The polymers are synthesized with magnetic nanoparticles as the core, water-soluble dendritic polyethyleneimine as the monomer and the ovalbumin as the template. The prepared imprinted polymers showed thin imprinted shell, biocompatibility and superparamagnetic properties. The resultant materials exhibited fast kinetics, high adsorption capacity, perfect selectivity and reusability. More important, they can absorb the template glycoprotein from the neutral solution and successfully be applied to recognize the ovalbumin from egg white, which means that they can provide an alternate method to isolate glycoprotein from bodily fluids.

Selective extraction of gallic acid in pomegranate rind using surface imprinting polymers over magnetic carbon nanotubes.

A novel surface imprinting polymer based on magnetic carbon nanotubes was prepared using dendritic polyethyleneimine as functional monomer to amplify the number of imprinted cavities. The characteristics of resulting polymers were evaluated by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and vibrating sample magnetometer (VSM). Results suggest that magnetic nanoparticles are deposited onto the surface of multiwalled carbon nanotubes and the imprinted shell is coated on the surface of magnetic carbon nanotubes with a thickness of approximately 8 nm. Magnetic imprinted polymers are sensitive to magnetic fields and can be easily separated within 3 s using an external magnet. The adsorption results indicate that the obtained imprinted polymers have fast kinetics, an ultrahigh adsorption capacity of 479.9 mg g(-1), and satisfactory selectivity towards the template molecule. The prepared materials have excellent stability with no obvious deterioration after six adsorption-regeneration cycles. In addition, a method for determination of gallic acid (GA) in pomegranate rind was developed, using a combination of the prepared polymers used as solid-phase extraction (SPE) sorbents and high-performance liquid chromatography (HPLC) for rapid isolation and determination of GA. The limit of detection of the proposed method is 0.001 µg mL(-1), and the intra and inter-day relative standard deviations (RSDs) are lower than 3.8% and 5.3%, respectively. The recoveries of GA from pomegranate rind extract are in the range 98.2-103.6% with RSDs lower than 4.3%.

One-step preparation of magnetic imprinted nanoparticles adopting dopamine-cupric ion as a co-monomer for the specific recognition of bovine hemoglobin.

A novel magnetic core-shell polydopamine-cupric ion complex imprinted polymer was prepared in one-step through surface imprinting technology, which could specifically recognize bovine hemoglobin from the real blood samples. The polymerization conditions and adsorption performance of the resultant nanomaterials were investigated in detail. The results showed that the cupric ion played an important role in the recognition of template proteins. The saturating adsorption capacity of this kind of imprinted polymers was 2.23 times greater than those of imprinted polymers without cupric ion. The imprinting factor of the imprinted materials was as high as 4.23 for the template molecule. The selective separation bovine hemoglobin from the real blood sample is successfully applied. In addition, the prepared materials had excellent stability and no obvious deterioration after five adsorption-regeneration cycles. Easy preparation, rapid separation, high binding capacity and satisfactory selectivity for the template protein make this polymer attractive in the separation of high-abundance proteins.

Unveiling a pH-Responsive Dual-Androgen-Blocking Magnetic Molecularly Imprinted Polymer for Enhanced Synergistic Therapy of Prostate Cancer.

Prostate cancer is the most common malignancy diagnosed in men. Androgens are directly related to its pathogenesis. Inhibition of the androgen receptor (AR) is considered to be the most promising therapeutic approach for the treatment of prostate cancer. In this study, a new type of pH-responsive dual androgen-blocking nanodrug (FASC MIPs) based on a molecularly imprinted polymer has been designed and synthesized. The nanodrug could selectively sequester testosterone from the prostate tumor through specific molecular imprinting sites and simultaneously deliver the AR inhibitory drug bicalutamide, which ultimately leads to enhanced synergistic therapy of prostate cancer. FASC MIPs demonstrate excellent pH responsiveness in a simulated tumor microenvironment due to the presence of chitosan and significantly inhibit the growth of prostate cancer cells (LNCaP cells) by blocking the G1 phase of cytokinesis. Additionally, the nanodrug also displayed excellent antitumor properties in a xenograft mouse model of prostate cancer without any sign of detrimental effects on healthy tissues and organs. Both in vitro and in vivo studies verified the augmented and synergistic therapeutic effects of FASC MIPs, and the proposed dual-androgen-blocking strategy could explore novel avenues in prostate cancer treatment.

Bio-inspired hydrogels with fibrous structure: A review on design and biomedical applications.

Numerous tissues in the human body have fibrous structures, including the extracellular matrix, muscles, and heart, which perform critical biological functions and have exceptional mechanical strength. Due to their high-water content, softness, biocompatibility and elastic nature, hydrogels resemble biological tissues. Traditional hydrogels, on the other hand, have weak mechanical properties and lack tissue-like fibrous structures, limiting their potential applications. Thus, bio-inspired hydrogels with fibrous architectures have piqued the curiosity of biomedical researchers. Here, we review fabrication strategies for fibrous hydrogels and their recent progress in the biomedical fields of wound dressings, drug delivery, tissue engineering scaffolds and bioadhesives. Challenges and future perspectives are also discussed.

Multi-stimuli responsive molecularly imprinted nanoparticles with tailorable affinity for modulated specific recognition of human serum albumin.

A kind of novel multi-stimuli responsive molecularly imprinted polymers with bovine serum albumin (BSA) as a dummy template (MSR-BSA-MIPs) was fabricated for specific recognition of human serum albumin (HSA) with modulated affinity. The MSR-BSA-MIPs were prepared through free radical polymerization using vinyl modified magnetic nanoparticles as substrates, bovine serum albumin (BSA), with high amino acid sequence similarity but low price compared to HSA, as the dummy template, N-(3-(dimethylamino)-propyl)-methacrylamide (DMAPMA) and N-isopropylacrylamide (NIPAm) as functional monomers with ionic strength and temperature response. The conditions of polymerization, adsorption and elution were systematically investigated. As expected, the obtained MSR-BSA-MIPs exhibited rapid dispersion or separation states under magnetic control, flexible conversion of adsorption and desorption for the target protein under temperature or ionic strength adjustment. Ten adsorption-desorption cycles were carried out with a little decrease in adsorption capacity under two different elution methods, which also inspired us to combine two elution methods while considering both the stability and adsorption capacity of MSR-BSA-MIPs. The adsorption capacity (Q) and imprinting factor (IF) of MSR-BSA-MIPs for HSA are 43.01 mg g-1 and 4.26, respectively. Furthermore, the blood was opted as a realistic specimen for evaluating the adsorption capability of the proposed adsorbent, emphasizing its good practicality for target protein recognition and enrichment.

Preparation of lightweight daisy-like magnetic molecularly imprinted polymers via etching synergized template immobilization for enhanced rapid detection of trace 17ß-estradiol.

17ß-estradiol (E2), as one of the pharmaceutical and personal care product, frequently contaminates environmental water as estrogen pollutant and possesses great risk to human survival as well as the sustainable development of the ecosystem. Herein, to achieve an effective adsorbent system for the selective removal of E2 from the environmental water, Fe3O4 nanoparticles are subjected to chemical etching to reduce the overall mass and then employed as carriers to prepare a novel type of lightweight daisy-like magnetic molecularly imprinted polymers (LD-MMIPs) adopting template immobilization strategy. The LD-MMIPs based etched magnetic nanoparticles not only exhibit light mass but also have plentiful imprinted sites in the etched channels, which significantly increases the adsorption capacity for E2. The daisy-like LD-MMIPs own strong magnetic responsiveness, well crystallinity, fast binding kinetics, high adsorption amount, and excellent selectivity. Moreover, combining with HPLC, the LD-MMIPs as adsorbents have been successfully used to specifically recognize and detect trace E2 in environmental water. Thus, the proposed LD-MMIPs with high adsorption capacity hold great potential in monitoring water pollution. Additionally, this work also provides an alternative strategy for improving the adsorption capacity of magnetic molecularly imprinted polymers through a convenient chemical etching technology.

Fabrication of acid-resistant imprinted layer on magnetic nanomaterials for selective extraction of chlorogenic acid in Honeysuckle.

The common elution process of molecularly imprinted polymers (MIPs) is carried out in an acidic medium, which greatly affects the stability and reusability of synthetic MIPs, especially for magnetic MIPs. In this study, we fabricated an acid-resistant imprinted layer formed by phase-transitioned lysozyme on magnetic nanomaterials for selective extraction of chlorogenic acid in Honeysuckle, which often coexists with structural analogs. The newly designed acid-resistant imprinted layer can not only protect the internal magnetic core from denudation and dissolution, but also maintain the integrity of the imprinted layer during the elution process. The resultant magnetic MIPs exhibited good stability with no change on morphology after the repeatedly eluting process, and satisfactory reusability that can be used at least ten adsorption-desorption cycles with almost no decrease for adsorption capacity. In addition, the resultant materials possess satisfactory magnetism, uniform morphology with typical core-shell structure, stable crystallization, and good adsorption performance showing on high adsorption amount (10.82 mg g-1), fast kinetic equilibrium time (as short as 30 min), and satisfactory selectivity (IF = 2.85, SC > 1.5). At last, the obtained magnetic MIPs as adsorbents coupled with HPLC were successfully used to selective extract CGA in Honeysuckle samples with the high recoveries in the range of 92.0-104.4%, and the contents of CGA in Honeysuckle samples from the different origin are calculated in the range of 0.98%-1.24%.

Fabrication of metal coordination-synergistic magnetic imprinted microspheres based on ligand-free Fe3O4-Cu for specific recognition of bovine hemoglobin.

In this work, a synergistic imprinting strategy combined with metal coordination based on ligand-free Fe3O4-Cu was proposed to fabricate molecularly imprinted polymers (MIPs) for the recognition and isolation of bovine hemoglobin (BHb) specifically in biological samples. Copper doped magnetic microspheres prepared solvothermally in a one-pot pathway act as both magnetic core and metal affinity substrate. Upon anchoring BHb to Fe3O4-Cu through metal coordination, the imprinted layer was formed via dopamine self-polymerization. Profiting from the synergistic effect, the obtained imprinted microspheres exhibited an enhanced adsorption performance with the adsorption capacity of 400.86 mg g-1, imprinting factor of 11.88, selectivity coefficient above 5.8, superior to most of other reported BHb-MIPs. Furthermore, kinetic adsorption analyses pointed to a chemisorption-limited process as described by the pseudo-second-order model, and the isothermal adsorption analyses implied monolayer adsorption, as described by the Langmuir model. In addition, the resultant magnetic MIPs can be used at least six adsorption-desorption cycles without re-incubation in the metallic salt solution, avoiding secondary environmental pollution. Furthermore, the well-defined materials showed selectivity both in individual protein samples and bovine serum, providing a promising potential in bioseparation.

Highly sensitive and spatially resolved polyvinyl alcohol/acrylamide photopolymer for real-time holographic applications.

By employing low molecular-weight polyvinyl alcohol (PVA) as binder, the spatial resolution of a red-sensitive PVA/acrylamide based photopolymer are improved from 1000 lines/mm to 3000 lines/mm. By increasing the ambient temperature during the holographic recording, the photosensitivity of photopolymer is also increased about 5 times. The optimized photopolymer system has high capacity such as high photosensitivity (8 mJ/cm(2)), high spatial resolution (over 3000 lines/mm) and high diffraction efficiency (over 94%). To our knowledge, its holographic recording performance is the best of ever reported PVA/acrylamide based photopolymer systems. It has good application prospects in real-time holographic interferometry, holographic storage and holographic display.

Discovery of the genus Cycloxenus Arrow, 1925 (Coleoptera, Euxestidae) in mainland China, with the description of a new species.

The termitophilous genus Cycloxenus Arrow (Coleoptera, Euxestidae) is reported from mainland China for the first time. A new species, Cycloxenus guangxiensis sp. nov., is described from Guangxi Province, China. The new species lives in nests of a fungus-growing termite (Odontotermes sp.) where it can be collected in the fungus gardens of the termite colony. The new species is compared with its congeners and new biological information for the genus Cycloxenus is provided. An identification key to all known Cycloxenus species is also provided.

Nanoscale Bupivacaine Formulations To Enhance the Duration and Safety of Intravenous Regional Anesthesia.

Intravenous regional anesthesia (IVRA; Bier block) is commonly used to anesthetize an extremity for surgery. Limitations of the procedure include pain from the required tourniquet, the toxicity that can occur from systemic release of local anesthetics, and the lack of postoperative pain relief. We hypothesized that the nanoencapsulation of the local anesthetic would prolong local anesthesia and enhance safety. Here, we developed an ∼15 nm micellar bupivacaine formulation (M-Bup) and tested it in a rat tail vein IVRA model, in which active agents were restricted in the tail by a tourniquet for 15 min. After tourniquet removal, M-Bup provided local anesthesia for 4.5 h, which was two times longer than that from a larger dose of free bupivacaine. Approximately 100 nm liposomal bupivacaine (L-Bup) with the same drug dose as M-Bup did not cause anesthesia. Blood levels of bupivacaine after tourniquet removal were lower in animals receiving M-Bup than L-Bup or free bupivacaine, demonstrating enhanced safety. Tissue reaction to M-Bup was benign.