Polymers in 3D printing of external maxillofacial prostheses and in their retention systems.

Maxillofacial defects, arising from trauma, oncological disease or congenital abnormalities, detrimentally affect daily life. Prosthetic repair offers the aesthetic and functional reconstruction with the help of materials mimicking natural tissues. 3D polymer printing enables the design of patient-specific prostheses with high structural complexity, as well as rapid and low-cost fabrication on-demand. However, 3D printing for prosthetics is still in the early stage of development and faces various challenges for widespread use. This is because the most suitable polymers for maxillofacial restoration are soft materials that do not have the required printability, mechanical strength of the printed parts, as well as functionality. This review focuses on the challenges and opportunities of 3D printing techniques for production of polymer maxillofacial prostheses using computer-aided design and modeling software. Review discusses the widely used polymers, as well as their blends and composites, which meet the most important assessment criteria, such as the physicochemical, biological, aesthetic properties and processability in 3D printing. In addition, strategies for improving the polymer properties, such as their printability, mechanical strength, and their ability to print multimaterial and architectural structures are highlighted. The current state of the prosthetic retention system is presented with a focus on actively used polymer adhesives and the recently implemented prosthesis-supporting osseointegrated implants, with an emphasis on their creation from 3D-printed polymers. The successful prosthetics is discussed in terms of the specificity of polymer materials at the restoration site. The approaches and technological prospects are also explored through the examples of the nasal, auricle and ocular prostheses, ranging from prototypes to end-use products.

Sorption properties of pristine and functionalized magnetic carbon nanotubes in relation to double-stranded DNA.

BACKGROUND: Owing to improvement of the molecular diagnostic methods using purified preparations of nucleic acids (NAs), the development of effective methods providing the isolation of DNA is still relevant. The sorption properties of magnetic multi-walled carbon nanotubes (MWCNTs), oxidized MWCNTs and MWCNTs (pristine and oxidized) modified with polydiallyldimethylammonium chloride (pDADMAC) with respect to double strained DNA have been studied. RESULTS: It was shown that in the presence of MWCNTs/pDADMAC particles the DNA molecules were reversibly retained by the particle's surface. The optimal conditions for each step of DNA extraction from model solutions using the obtained material were selected. A comparative evaluation of the effectiveness of the proposed method for DNA isolation based on the results of spectrophotometry and real-time PCR was carried out. It was shown that the desorbed DNA was efficiently amplified in PCR, inhibition of polymerase did not occurred. Probable mechanisms of DNA retention due to the influence of residual impurities of catalysts in the MWCNT composition, as well as the surface charge of nanotubes are proposed. CONCLUSION: Sequentially oxidized and coated with pDADMAC magnetically susceptible CNTs are seemed to be a promising material for development of low-cost systems proving an easy isolation, storage, and subsequent use of dsDNA in molecular diagnostics. The sorption properties of such systems are determined with highly developed specific surface area and their chemical composition.

Diagnostic efficacy of the new prospective biomarker's combination CA 15-3 and CA-62 for early-stage breast cancer detection: Results of the blind prospective-retrospective clinical study.

BACKGROUND: Combination of different cancer markers is often used for predicting tumor growth, for the response to cancer therapy, and for increase in the positive diagnosis ratio in the malignant tumors. OBJECTIVE: Evaluation of the diagnostic efficacy of CA 15-3 and CA-62 cancer markers combination for early stages of breast cancer (BC) detection. METHODS: This blind study was performed on 2 clinically validated Sets that included serum measurements of CA 15-3 ELISA and CLIA-CA-62 assays in 488 serum samples with TNM classification. A study included 300 BC patients (254 at Stages I and II, 20 with ductal carcinoma in situ (DCIS), and 26 Stages III and IV patients), 47 patients with breast benign diseases, and 141 healthy controls. RESULTS: Sensitivity for DCIS & Stage I breast cancer detection was 75% at 100% Specificity (AUC = 0.895) using a following combination of two antigens: 10 < CA15-3 < 46 U/ml and CA-62 ⩾ 6300 U/ml, which allows eliminating false positive results. CONCLUSIONS: The results obtained in a blind study demonstrate that a combination of CA15-3 with CA-62 yields 75% Sensitivity at 100% Specificity for DCIS and Stage I breast cancer detection, which has a potential to be integrated into existing screening programs.

Fabrication of moldable chitosan gels via thermally induced phase separation in aqueous alcohol solutions.

Wide application of chitosan in modern technologies is limited by the lack of reliable and low-cost techniques to prepare size-tuned constructs with a complex surface morphology, improved optical and mechanical properties. We report a new simple method for preparation of transparent thermoreversible chitosan alcogels from chitosan/H2O/ethanol ternary systems. This method, termed "low temperature thermally induced phase separation under non-freezing conditions" (LT-TIPS-NF), fine tunes gelation by adjusting only temperature (from 5 to -25 °C) and varying the initial content of chitosan (from 0.5 to 2.0 wt%) and ethanol (from 28.5 to 47.5 vol%). Transparent non-swelling final constructs of complex shape are prepared by fixing the pre-formed alcogels with a base solution. The size of the gel constructs is limited only by the dimensions of the mold and the cooling chamber. The LT-TIPS-NF is applicable both in injection molding and 3D printing techniques. The in vitro and in vivo experiments show the absence of prominent cytotoxicity and well-defined cell adhesion on the obtained hydrogels. Thus, this facile and scalable technique provides the multifunctional chitosan gel preparation with easily controlled properties exploiting inexpensive, renewable, and environmentally friendly source polysaccharide. These materials have prospects for a variety of uses, especially for biomedical applications.

Sorption of nucleic acids and proteins on polyaniline and polyaramide nano-coatings as studied by spectral-correlation interferometry in a real time mode.

Polyaniline (PANI) and polyaramides deposited on the surfaces of glass slides and particulate silica were studied as adsorbents of nucleic acids and proteins by flow-through spectral correlation interferometry and solid-state extraction using spin-cartridges. Double stranded DNA from E. coli as well as pepsin, bovine serum albumin and lysozyme were the analytes studied in contact with the polymer nanolayers in phosphate buffer solution, pH 7.2. None of the coated glass slides could bind the DNA, which passed them practically without adsorption. In contact with polyaramides, the proteins of pI > 4 reversibly formed the 0.2-2.5 nm-thick adsorption layers decomposing on further rinsing with the protein-free eluent. In contact with PANI, the proteins formed stable adsorption layers at pH 7.2, which needed the pH 3.0 to be eluted. Thus, in a neutral aqueous medium optimal for separation of biopolymers, polyaramides, although did not retain DNA, had a weaker affinity to proteins as compared to PANI. Since the recovery of DNA passed through the PANI-coated silica was the maximal among the particulate adsorbents, the PANI-modified composites were preferred as the carriers for the single-step isolation of nucleic acids from complex biological mixtures.

Sorption behavior of polyaramides in relation to isolation of nucleic acids and proteins.

The effect of chemical composition and morphology of the surface layers of new polyaramide-containing sorbents on the mechanism of selective sorption of nucleic acids and proteins was investigated as compared to the previously studied sorbents modified with fluoropolymers and polyaniline (high-throughput materials providing one-step isolation of DNA from biological mixtures). A series of silica-based sorbents modified with polyaramides having consistently varying structure and containing the set of "key" structural elements (aromatic units and nitrogen atoms in the backbone, fluorinated groups), and various donor and acceptor moieties was prepared. The chemical composition of the polymer coatings was evaluated by X-ray photoelectron spectroscopy. The surface morphology was studied by scanning probe microscopy. The sorption properties were investigated by passing the mixtures containing DNA, RNA and proteins of different nature through the cartridges containing the obtained sorbents. All the investigated materials weakly retain double-stranded DNA but effectively retain RNA and proteins. The sorption capacity of the sorbents depends on the protein nature. The observed sorption behavior was shown to be determined by the chemical structure and not by the morphology of the polymer coating. It was proposed that similarity of the sorption properties of the series of chemically different polymers could be determined by similar total input of different sorption mechanisms.

Fluoroplast-polyaniline-coated adsorbent for one-step isolation of DNA for PCR detection of viral hepatitides (HBV and TTV).

AIMS: To demonstrate the effectiveness of application of the adsorbent successively modified with nano-layers of fluoroplast and polyaniline for one-step isolation of DNA of hepatitis B virus and transfusion-transmitted virus from human serum. MATERIALS & METHODS: The technique is based on the application of the spin-cartridges containing porous adsorbent for one-step viral DNA isolation from serum followed by polymerase chain reaction. RESULTS: The developed adsorbent was shown to be effective for one-step isolation of viral DNA from serum samples for polymerase chain reaction diagnostics. CONCLUSION: The effectiveness of the developed adsorbent application for isolation of viral DNA from serum for polymerase chain reaction diagnostics was confirmed in comparison with standard methods. Thus, the facile sample preparation method of viral DNA isolation was elaborated.

Novel composite matrices modified with nanolayers of polymers as perspective materials for separation of biomolecules and bioanalysis.

AIMS: A new approach for the preparation of adsorbents for one-step isolation/purification of DNA from different samples (e.g., bacterial lysates, smears and blood) has been developed. MATERIALS & METHODS: The technique is based on the use of porous silica preliminary treated with ozone followed by grafting of polymer nanolayers on the activated carrier surface. The chemical nature of active centers, their stability and conditions for the use of the activated support as heterogeneous initiator of different macromolecular reactions were studied. RESULTS: The adsorbents modified with thin (~3.0-7.5 nm) polytetrafluoroethylene and polyaniline layers were prepared and characterized. Sorption properties of the obtained adsorbents were demonstrated on examples of express (2-5 min) one-step DNA isolation for direct use in PCR diagnostics. CONCLUSION: The effectiveness of the developed adsorbents used for DNA isolation and purification was confirmed in comparison with the standard methods. Thus, a facile (alternative in relation to irradiation postpolymerization or standard oxidative polymerization techniques) manufacturing method of the materials for nucleic acids sample preparation was developed.