Amphiphilic Block Copolymers Containing Benzenesulfonyl Azide Groups as Visible Light-Responsive Drug Carriers for Image-Guided Delivery.

Nanoparticles (NPs) containing light-responsive polymers and imaging agents show great promise for controlled drug delivery. However, most light-responsive NPs rely on short-wavelength excitation, resulting in poor tissue penetration and potential cytotoxicity. Moreover, excessively sensitive NPs may prematurely release drugs during storage and circulation, diminishing their efficacy and causing off-target toxicity. Herein, we report visible-light-responsive NPs composed of an amphiphilic block copolymer containing responsive 4-acrylamide benzenesulfonyl azide (ABSA) and hydrophilic N,N'-dimethylacrylamide (DMA) units. The polymer pDMA-ABSA was loaded with the chemotherapy drug dasatinib and zinc tetraphenylporphyrin (ZnTPP). ZnTPP acted as an imaging reagent and a photosensitizer to reduce ABSA upon visible light irradiation, converting hydrophobic units to hydrophilic units and disrupting NPs to trigger drug release. These NPs enabled real-time fluorescence imaging in cells and exhibited synergistic chemophotodynamic therapy against multiple cancer cell lines. Our light-responsive NP platform holds great promise for controlled drug delivery and cancer theranostics, circumventing the limitations of traditional photosensitive nanosystems.

Light-mediated intracellular polymerization.

The synthesis of synthetic intracellular polymers offers groundbreaking possibilities in cellular biology and medical research, allowing for novel experiments in drug delivery, bioimaging and targeted cancer therapies. These macromolecules, composed of biocompatible monomers, are pivotal in manipulating cellular functions and pathways due to their bioavailability, cytocompatibility and distinct chemical properties. This protocol details two innovative methods for intracellular polymerization. The first one uses 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (Irgacure 2959) as a photoinitiator for free radical polymerization under UV light (365 nm, 5 mW/cm2). The second method employs photoinduced electron transfer-reversible addition-fragmentation chain-transfer polymerization with visible light (470 nm, 100 mW/cm2). We further elaborate on isolating these intracellular polymers by streptavidin/biotin interaction or immobilized metal ion affinity chromatography for polymers tagged with biotin or histidine. The entire process, from polymerization to isolation, takes ~48 h. Moreover, the intracellular polymers thus generated demonstrate significant potential in enhancing actin polymerization, in bioimaging applications and as a novel avenue in cancer treatment strategies. The protocol extends to animal models, providing a comprehensive approach from cellular to systemic applications. Users are advised to have a basic understanding of organic synthesis and cell biology techniques.

Conductive paper from lignocellulose wood microfibers coated with a nanocomposite of carbon nanotubes and conductive polymers.

Composite nanocoating of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) and aqueous dispersion of carbon nanotubes (CNT-PSS) on lignocellulose wood microfibers has been developed to make conductive microfibers and paper sheets. To construct the multilayers on wood microfibers, cationic poly(ethyleneimine) (PEI) has been used in alternate deposition with anionic conductive PEDOT-PSS and solubilized CNT-PSS. Using a Keithley microprobe measurement system, current-voltage measurements have been carried out on single composite microfibers after deposition of each layer to optimize the electrical properties of the coated microfibers. The conductivity of the resultant wood microfibers was in the range of 10(-2)-2 S cm(-1) depending on the architecture of the coated layer. Further, the conductivity of the coated wood microfibers increased up to 20 S cm(-1) by sandwiching multilayers of conductive co-polymer PEDOT-PSS with CNT-PSS through a polycation (PEI) interlayer. Moreover, paper hand sheets were manufactured from these coated wood microfibers with conductivity ranging from 1 to 20 S cm(-1). A paper composite structure consisting of conductive/dielectric/conductive layers that acts as a capacitor has also been fabricated and is reported.

Nitric oxide regulates cell behavior on an interactive cell-derived extracellular matrix scaffold.

During tissue injury and wound healing process, there are dynamic reciprocal interactions among cells, extracellular matrix (ECM), and mediating molecules which are crucial for functional tissue repair. Nitric oxide (NO) is one of the key mediating molecules that can positively regulate various biological activities involved in wound healing. Various ECM components serve as binding sites for cells and mediating molecules, and the interactions further stimulate cellular activities. Human mesenchymal stem cells (hMSCs) can migrate to the wound site and contribute to tissue regeneration through differentiation and paracrine signaling. The objective of this work was to investigate the regulatory effect of NO on hMSCs in an interactive ECM-rich microenvironment. In order to mimic the in vivo stromal environment in wound site, a cell-derived ECM scaffold that was able to release NO within the range of in vivo wound fluid NO level was fabricated. Results showed that the micro-molar level of NO released from the ECM scaffold had an inhibitory effect on cellular activities of hMSCs. The NO impaired cell growth, altered cell morphology, disrupted the F-actin organization, also decreased the expression of focal adhesion related molecules integrin α5 and paxillin. These results may contribute to the elucidation of how NO acts on hMSCs in wound healing process.

A three-field breast treatment technique with precise geometric matching using multileaf collimator-equipped linear accelerators.

PURPOSE: Many authors have studied the problems associated with the three-field breast treatment, yet the proposed solutions present their own difficulties. This study presents a technique that overcomes these difficulties, reduces scatter to the contralateral breast, and improves setup reproducibility. METHODS AND MATERIALS: Patients are set up with both arms raised superiorly on a breast board. A precise field-match is achieved by rotating the couch and collimator of the tangents, while the supraclavicular field is half-beam blocked using an independent jaw. The posterior borders of the tangents are conformally defined by multileaf collimation. Measurements were performed to verify the field matching and evaluate scatter doses. RESULT: A smooth dose transition was found at the match line at all depths. Corner blocks and lower wedges were not used, which reduced the scatter to the contralateral breast compared with our prior technique. CONCLUSION: The technique achieves a precise match while removing constraints on the tangents' length and decreasing scatter dose. Procedures for simulation, planning, and treatment have been devised, along with a new patient setup routine incorporating orthogonal setup films and tattoos. This technique has been successfully implemented in routine treatment since September 2001. A program calculating the setup parameters is available at our website.

Clinical features and management of Crohn's disease in Chinese patients.

BACKGROUND: An increasing incidence of Crohn's disease has been found in China in recent years. Our study has been focused on evaluating the diversity of the clinical manifestations of Crohn's disease in order to improve early diagnostic accuracy and therapeutic efficacy. METHODS: Thirty patients with active Crohn's disease were enrolled and their clinical data, including diagnostic and therapeutic results, were analyzed. Endoscopy combined with histological examination of biopsy specimens provided characteristic features of the disease. Transabdominal bowel sonography (TABS) was used for detecting intestinal complications. Nutritional supportive therapy was given to 20 subjects with active cases of the disease. RESULTS: Most patients were young adults with a higher proportion of females to males (ratio: 1.14:1). The disease affects any segment or a combination of segments along with the alimentary tract (from the mouth to the anus). In this study, the colon and small bowel were the major sites involved. Recurrent episodes of abdominal pain in the right lower quadrant and watery diarrhea were the most common symptoms. Granulomas were identifiable in nearly one-third (30.8%) of all biopsy specimens. In moderate cases of the disease, remission was achieved more quickly through the use of oral prednisone therapy than with SASP or 5-ASA. Beneficial effects on the host's nutritional status were observed. Immunosuppressives were used on an individual basis and showed variable therapeutic effects. Sixteen patients had surgery due to intestinal obstruction or failure to respond to drug therapies. Rapid improvement after surgery was reported. CONCLUSION: Endoscopy (with biopsy) and TABS were both crucial procedures for diagnosis. SASP (or 5-ASA) and prednisone were effective as inductive therapies. Azathioprine has demonstrable benefits after induction therapy with prednisone. Surgery, as an alternative treatment, provided another effective choice in selected patients.

Increasing mechanical strength of gelatin hydrogels by divalent metal ion removal.

The usage of gelatin hydrogel is limited due to its instability and poor mechanical properties, especially under physiological conditions. Divalent metal ions present in gelatin such as Ca(2+) and Fe(2+) play important roles in the gelatin molecule interactions. The objective of this study was to determine the impact of divalent ion removal on the stability and mechanical properties of gelatin gels with and without chemical crosslinking. The gelatin solution was purified by Chelex resin to replace divalent metal ions with sodium ions. The gel was then chemically crosslinked by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC). Results showed that the removal of divalent metal ions significantly impacted the formation of the gelatin network. The purified gelatin hydrogels had less interactions between gelatin molecules and form larger-pore network which enabled EDC to penetrate and crosslink the gel more efficiently. The crosslinked purified gels showed small swelling ratio, higher crosslinking density and dramatically increased storage and loss moduli. The removal of divalent ions is a simple yet effective method that can significantly improve the stability and strength of gelatin hydrogels. The in vitro cell culture demonstrated that the purified gelatin maintained its ability to support cell attachment and spreading.

[Investigation of accuracy of premolar length measured by cone beam CT in vivo].

OBJECTIVE: To investigate the feasibility and accuracy of length measurement of in vivo teeth by using cone beam CT (CBCT). METHODS: Before orthodontic extraction, 109 vital premolars from 40 participants were scanned by using CBCT and reconstructed by using InVivoDental software. Buccal-lingual sectional images along the long axis of teeth were then acquired, and the crown, root, and tooth length were measured separately. After careful extraction and fixation, the corresponding length of the same tooth was measured by using a digital caliper. CBCT measurement accuracy was then verified by using physical measurements as reference. RESULTS: CBCT and the physical method did not obtain significantly different measurements of the root, crown, and tooth length of experimental teeth (P=0.790, P=0.621, P=0.657, respectively), and the measurements were found to be consistent. The 95% limits of agreement of root, crown, and tooth length were -1.10 mm to 1.13 mm, -1.00 mm to 0.96 mm, and -1.00 mm to 1.05 mm, respectively. CONCLUSION: The difference between CBCT and the physical method was not significant, and good consistency was shown. CBCT could be applied in noninvasive measurement of in vivo teeth.

Porous biocompatible three-dimensional scaffolds of cellulose microfiber/gelatin composites for cell culture.

Physiological tissues, including brain and other organs, have three-dimensional (3-D) aspects that need to be supported to model them in vitro. Here we report the use of cellulose microfibers combined with cross-linked gelatin to make biocompatible porous microscaffolds for the sustained growth of brain cell and human mesenchymal stem cells (hMSCs) in 3-D structure. Live imaging using confocal microscopy indicated that 3-D microscaffolds composed of gelatin or cellulose fiber/gelatin both supported brain cell adhesion and growth for 16days in vitro. Cellulose microfiber/gelatin composites containing up to 75% cellulose fibers can withstand a higher mechanical load than gelatin alone, and composites also provided linear pathways along which brain cells could grow compared to more clumped cell growth in gelatin alone. Therefore, the bulk cellulose microfiber provides a novel skeleton in this new scaffold material. Cellulose fiber/gelatin scaffold supported hMSCs growth and extracellular matrix formation. hMSCs osteogenic and adipogenic assays indicated that hMSCs cultured in cellulose fiber/gelatin composite preserved the multilineage differentiation potential. As natural, biocompatible components, the combination of gelatin and cellulose microfibers, fabricated into 3-D matrices, may therefore provide optimal porosity and tensile strength for long-term maintenance and observation of cells.

Cellulose fiber-enzyme composites fabricated through layer-by-layer nanoassembly.

Cellulose microfibers were coated with enzymes, laccase and urease, through layer-by-layer assembly by alternate adsorption with oppositely charged polycations. The formation of organized polyelectrolyte and enzyme multilayer films of 15-20 nm thickness was demonstrated by quartz crystal microbalance, zeta-potential analysis, and confocal laser scanning microscopy. These biocomposites retained enzymatic catalytic activity, which was proportional to the number of coated enzyme layers. For laccase-fiber composites, around 50% of its initial activity was retained after 2 weeks of storage at 4 degrees C. The synthesis of calcium carbonate microparticles on urease-fiber composites confirmed urease functionality and demonstrated its possible applications. This strategy could be employed to fabricate fiber-based composites with novel biological functions.