Synthesis, monomer conversion, and mechanical properties of polylysine based dental composites.

OBJECTIVE: The aim of this study was to synthesize a new bioactive and antibacterial composite by incorporating reactive calcium phosphate and antibacterial polylysine into a resin matrix and evaluate the effect of these fillers on structural analysis, degree of monomer conversion, mechanical properties, and bioactivity of these newly developed polypropylene based dental composites. METHODOLOGY: Stock monomers were prepared by mixing urethane dimethacrylate and polypropylene glycol dimethacrylate and combined with 40 wt% silica to make experimental control (E-C). The other three experimental groups contained a fixed percentage of silica (40 wt%), monocalcium phosphate monohydrate, and ß-tri calcium phosphate (5 wt% each) with varying amounts of polylysine (PL). These groups include E-CCP0 (0 wt% PL), E-CCP5 (5 wt% PL) and E-CCP10 (10 wt% PL). The commercial control used was Filtek™ Z250 3M ESPE. The degree of conversion was assessed by using Fourier transform infrared spectroscopy (FTIR). Compressive strength and Vicker's micro hardness testing were evaluated after 24 h of curing the samples. For bioactivity, prepared samples were placed in simulated body fluid for 0, 1, 7, and 28 days and were analyzed using a scanning electron microscope (SEM). SPSS 23 was used to analyze the data and one-way ANOVA and post hoc tukey's test were done, where the significant level was set ≤0.05. RESULTS: Group E-C showed better mechanical properties than other experimental and commercial control groups. Group E-C showed the highest degree of conversion (72.72 ± 1.69%) followed by E-CCP0 (72.43 ± 1.47%), Z250 (72.26 ± 1.75%), E-CCP10 (71.07 ± 0.19%), and lowest value was shown by E-CCP5 (68.85 ± 7.23%). In shear bond testing the maximum value was obtained by E-C. The order in decreasing value of bond strength is E-C (8.13 ± 3.5 MPa) > Z250 (2.15 ± 1.1 MPa) > E-CCP10 (2.08 ± 2.1 MPa) > E-CCP5 (0.94 ± 0.8 MPa) > E-CCP0 (0.66 ± 0.2 MPa). In compressive testing, the maximum strength was observed by commercial control i.e., Z250 (210.36 ± 18 MPa) and E-C (206.55 ± 23 MPa), followed by E-CCP0 (108.06 ± 19 MPa), E-CCP5 (94.16 ± 9 MPa), and E-CCP10 (80.80 ± 13 MPa). The maximum number of hardness was shown by E-C (93.04 ± 8.23) followed by E-CCP0 (38.93 ± 9.21) > E-CCP10 (35.21 ± 12.31) > E-CCP5 (34.34 ± 12.49) > Z250 (25 ± 2.61). SEM images showed that the maximum apatite layer as shown by E-CCP10 and the order followed as E-CCP10 > E-CCP5 > E-CCP0 >Z250> E-C. CONCLUSION: The experimental formulation showed an optimal degree of conversion with compromised mechanical properties when the polylysine percentage was increased. Apatite layer formation and polylysine at the interface may result in remineralization and ultimately lead to the prevention of secondary caries formation.

In-depth drug delivery to tumoral soft tissues via pH responsive hydrogel.

A pH responsive nanoparticle-hydrogel hybrid drug delivery system was investigated for in-depth anticancer drug delivery to solid tumours. It consists of acid susceptible polymer nanoparticles loaded in a chitosan hydrogel. The hybrid formulation was characterized by UV-visible spectroscopy, FTIR, SEM, TEM, particle size analysis, zeta potential measurement and viscosity measurement. Drug encapsulation and nanoparticle loading efficiencies were found to be 48% and 72% respectively which describes the efficient interaction of the chemical entities in this hybrid drug delivery system. The hydrogel exhibited pH responsive behaviour: minimal drug and nanoparticle release at physiological pH but an increase in viscosity under acidic conditions and fast nanoparticle and drug release. The cytotoxicity of the drug loaded hydrogel was investigated against the MCF-7 breast cancer cell line along with the drug and nanoparticles without hydrogel. The drug loaded hydrogel showed a better cytotoxic effect on MCF-7 cancer cells. Thus, drug loaded nanoparticles containing hydrogel could be a better option for maximum drug distribution in tumours.

Ceramic Stereolithography of Bioactive Glasses: Influence of Resin Composition on Curing Behavior and Green Body Properties.

Herein we report on the preparation of a bioactive glass (BAG)-based photocurable resin for the additive manufacturing of BAG scaffolds with high filler loadings. The preparation of glass/ceramics resins for stereolithography with high filler loading is always a challenge, especially for fillers with a high refractive index variance. Various photocurable resin compositions with and without bioactive glass fillers have been investigated to see the influence of bioactive glass on physical properties of the resin and resulting green body. The effect of concentration of monomers, reactive diluent, light absorber (Sudan orange G dye), photoinitiator (PI), non-reactive diluent, and fillers (BAG) on rheology and photocuring behavior of the resin and tomography of the resulting 3D structures have been investigated. The BAG contents affect the rheology of resin and influence the rate of the polymerization reaction. The resin compositions with 55-60% BAG, 10% PEG-200 (diluent), 1% of PI and 0.015% of the dye were found to be suitable compositions for the stereolithographic fabrication. A higher percentage of PI caused over-curing, while a higher amount of dye decreased the cure depth of the resin. The micro-computed tomography (µ-CT) and scanning electron microscopic (SEM) images of the resulting green bodies display a relatively dense glass scaffold without any visible cracks and good interlayer connection and surface finishing. These properties play an important role in the mechanical behavior of 3D scaffolds. This study will be helpful to prepare high density glass/ceramic slurries and optimize their printing properties.

Efficient Preparation of a Nonenzymatic Nanoassembly Based on Cobalt-Substituted Polyoxometalate and Polyethylene Imine-Capped Silver Nanoparticles for the Electrochemical Sensing of Carbofuran.

The ever-growing exploitation of pesticides and their lethal effects on living beings have made it a dire need of the day to develop an accurate and reliable approach for their monitoring at trace levels. The designing of an enzyme-free electrocatalyst to electrochemically detect the pesticide residues is currently gaining much importance. In this study, a novel redox-sensing film was constructed successfully based on cobalt-substituted Dawson-type polyoxometalate [P2W17O61 (Co2+·OH2)]7- (Co-POM) and polyethylene imine (PEI)-capped silver nanoparticles (AgNPs). A nanohybrid assembly was fabricated on a glassy carbon electrode's surface by alternately depositing Co-POM and PEI-AgNPs using the layer-by-layer self-assembly method. The surface morphology of the immobilized CoPOM/AgNP multilayer nanoassembly was analyzed through scanning electron microscopy along with energy-dispersive spectroscopy for elemental analysis. The redox properties and surface morphologies of fabricated assemblies were evaluated by cyclic voltammetry and electrochemical impedance spectroscopy. The practicability and feasibility of the proposed sensing layer was tested for the detection of a highly toxic insecticide, that is, carbofuran. The fabricated sensor exhibited a limit of detection of 0.1 mM with a sensitivity of 13.11 µA mM-1 for carbofuran. The results depicted that the fabricated nonenzymatic hybrid film showed excellent electrocatalytic efficiency for the carbofuran oxidation. Furthermore, the obtained value of "apparent Km", that is, 0.4 mM, illustrates a good electro-oxidation activity of the sensor for the detection of carbofuran. The exceptionally stable redox activity of Co-POM, high surface area and greater conductivity of AgNPs, and the synergistic effect of all components of the film resulted in an excellent analytical performance of the proposed sensing assembly. This work provides a new direction to the progress and designing of nonenzymatic electrochemical sensors for pesticide determination in real samples.

Surface-modified polymeric nanoparticles for drug delivery to cancer cells.

INTRODUCTION: The utilization of polymeric nanoparticles, as drug payloads, has been extensively prevailed in cancer therapy. However, the precise distribution of these nanocarriers is restrained by various physiological and cellular obstacles. Nanoparticles must avoid nonspecific interactions with healthy cells and in vivo compartments to circumvent these barriers. Since in vivo interactions of nanoparticles are mainly dependent on surface properties of nanoparticles, efficient control on surface constituents is necessary for the determination of nanoparticles' fate in the body. AREAS COVERED: In this review, the surface-modified polymeric nanoparticles and their utilization in cancer treatment were elaborated. First, the interaction of nanoparticles with numerous in vivo barriers was highlighted. Second, different strategies to overcome these obstacles were described. Third, some inspiring examples of surface-modified nanoparticles were presented. Later, fabrication and characterization methods of surface-modified nanoparticles were discussed. Finally, the applications of these nanoparticles in different routes of treatments were explored. EXPERT OPINION: Surface modification of anticancer drug-loaded polymeric nanoparticles can enhance the efficacy, selective targeting, and biodistribution of the anticancer drug at the tumor site.

Biophysics and the nonlinear dynamics instigated by a special hormone.

Calcitonin, a potent hypocalcemic hormone, plays a vital role in inhibiting osteoclastic activities and suppressing bone removal. The physiological characteristics of calcitonin have long been discussed, along a few recommending calcitonin as a vestigial hormone. The basis for this article is to discuss the role of low and high levels of calcitonin in normal and osteoprotic bone turnover. The effect of calcitonin on the receptor activator of nuclear factor kappa-ligand and osteoclasts has been demonstrated using numerical simulations. This behavior recommends that treatment of osteoporosis via calcitonin does not provide the required upshots. For effectiveness calcitonin must be advised along with a combined therapy like aspirin which agrees with the experimental results available in the literature.

Incidence and management of cleft lip and palate in Pakistan.

OBJECTIVE: To compare the occurrence, distribution and management of clefts of lip and palate in local patients with the available data from India and China. METHODS: The retrospective study was conducted at the Interdisciplinary Research Centre in Biomedical Materials, COMSATS University Islamabad, Lahore Campus, Lahore, Pakistan, and comprised data related to a three-month period from January to March 2015 at two medical centres in Lahore. Data from Pakistani centres was analysed based on province, gender, age and clefts of lip and palate conditions and Spearman's correlation matrix. RESULTS: Of the 1574 cases, 1061(67.4%) were from Punjab, 361(23%) Khyber Pakhtunkhwa, 85(5%) Sindh and 67(4.2%) were from Azad Jammu and Kashmir. The incidence of clefts of lip and palate was higher in males than females. There was higher awareness of the need for timely management in new borns with clefts of lip and palate. Some patients seeking secondary treatment were also being surgically corrected. There is no national registry of children born with cleft defect, making it difficult to assess the full scale of the problem.. CONCLUSIONS: Based on available data, it is likely that there are many adults who have not been treated when younger..

Developing a synthetic composite membrane for cleft palate repair.

An oronasal fistula is a passage between the oral and nasal cavity. Currently, surgical procedures use mucosal flaps or collagen grafts to make a barrier between oral and nasal cavities. Our aim was to develop a cell-free synthetic repair material for closure of nasal fistulas. We surface functionalized electrospun polyurethane (PU) and poly-L-lactic acid (PLLA) and composite polymer (PU-PLLA) membranes with acrylic acid through plasma polymerization. Membranes were treated in a layer-by-layer approach to develop highly charged electrostatic layer that could bind heparin as a pro-angiogenic glycosaminoglycan. The properties were evaluated through physical, chemical, and mechanical characterization techniques. Cytotoxicity was tested with MC3T3 pre-osteoblast cell lines for 3, 7, and 14 days, and vasculogenesis was assessed by implantation into the chorio-allantoic membrane in chick embryos for 7 days. In vivo biocompatibility was assessed by subcutaneous implantation in rats for 1, 3, and 6 weeks. The membranes consisted of random fibers of PLLA-PU with fiber diameters of 0.47 and 0.12 µm, respectively. Significantly higher cell proliferation and migration of MC3T3 cells at 3, 7, and 14 days were shown on plasma-coated membranes compared with uncoated membranes. Further, it was found that plasma-coated membranes were more angiogenic than controls. In vivo implantation of membranes in rats did not reveal any gross toxicity to the materials, and wound healing was comparable with the native tissue repair (sham group). We therefore present a plasma-functionalized electrospun composite polymer membrane for use in the treatment of fistulas. These membranes are flexible, non-cytotoxic, and angiogenic, and we hope it should lead to permanent closure of oronasal fistula.