In vitro and in vivo effects of deoxyribonucleic acid-based coatings funtionalized with vascular endothelial growth factor

Dental Materials Applied to 3D and 4D Printing Technologies: A Review

As computer-aided design and computer-aided manufacturing (CAD/CAM) technologies have matured, three-dimensional (3D) printing materials suitable for dentistry have attracted considerable research interest, owing to their high efficiency and low cost for clinical treatment. Three-dimensional printing technology, also known as additive manufacturing, has developed rapidly over the last forty years, with gradual application in various fields from industry to dental sciences. Four-dimensional (4D) printing, defined as the fabrication of complex spontaneous structures that change over time in response to external stimuli in expected ways, includes the increasingly popular bioprinting. Existing 3D printing materials have varied characteristics and scopes of application; therefore, categorization is required. This review aims to classify, summarize, and discuss dental materials for 3D printing and 4D printing from a clinical perspective. Based on these, this review describes four major materials, i.e., polymers, metals, ceramics, and biomaterials. The manufacturing process of 3D printing and 4D printing materials, their characteristics, applicable printing technologies, and clinical application scope are described in detail. Furthermore, the development of composite materials for 3D printing is the main focus of future research, as combining multiple materials can improve the materials' properties. Updates in material sciences play important roles in dentistry; hence, the emergence of newer materials are expected to promote further innovations in dentistry.

Sequence Does Not Matter: The Biomedical Applications of DNA-Based Coatings and Cores

Biomedical applications of DNA are diverse but are usually associated with specific recognition of target nucleotide sequences or proteins and with gene delivery for therapeutic or biotechnological purposes. However, other aspects of DNA functionalities, like its nontoxicity, biodegradability, polyelectrolyte nature, stability, thermo-responsivity and charge transfer ability that are rather independent of its sequence, have recently become highly appreciated in material science and biomedicine. Whereas the latest achievements in structural DNA nanotechnology associated with DNA sequence recognition and Watson–Crick base pairing between complementary nucleotides are regularly reviewed, the recent uses of DNA as a raw material in biomedicine have not been summarized. This review paper describes the main biomedical applications of DNA that do not involve any synthesis or extraction of oligo- or polynucleotides with specified sequences. These sequence-independent applications currently include some types of drug delivery systems, biocompatible coatings, fire retardant and antimicrobial coatings and biosensors. The reinforcement of DNA properties by DNA complexation with nanoparticles is also described as a field of further research.

Layer-by-Layer assembled nano-drug delivery systems for cancer treatment

Nano-drug delivery systems (NDDS) are functional drug-loaded nanocarriers widely applied in cancer therapy. Recently, layer-by-layer (LbL) assembled NDDS have been demonstrated as one of the most promising platforms in delivery of anticancer therapeutics. Here, a brief review of the LbL assembled NDDS for cancer treatment is presented. The fundamentals of the LbL assembled NDDS are first interpreted with an emphasis on the formation mechanisms. Afterwards, the tailored encapsulation of anticancer therapeutics in LbL assembled NDDS are summarized. The state-of-art targeted delivery of LbL assembled NDDS, with special attention to the elaborately control over the passive and active targeting delivery, are represented. Then the controlled release of LbL assembled NDDS with various stimulus responsiveness are systematically reviewed. Finally, conclusions and perspectives on further advancing the LbL assembled NDDS toward more powerful and versatile platforms for cancer therapy are discussed.

Exploring the interdependence between self-organization and functional morphology in cellular systems

All living matter is subject to continuous adaptation and functional optimization via natural selection. Consequentially, structures with close morphological resemblance repeatedly appear across the phylogenetic tree. How these designs emerge at the cellular level is not fully understood. Here, we explore core concepts of functional morphology and discuss its cause and consequences, with a specific focus on emerging properties of self-organizing systems as the potential driving force. We conclude with open questions and limitations that are present when studying shape-function interdependence in single cells and cellular ensembles.

Utilizing DNA for functionalization of biomaterial surfaces

DNA sequences are widely used for gene transfer into cells including a number of substrate surface-based supporting systems, but due to its singular structure property profile, DNA also offers multiple options for noncanonical applications. The special case of using DNA and oligodeoxyribonucleotide (ODN) structures for surface functionalization of biomedical implants is summarized here with the major focus on (a) immobilization or anchoring of nucleic acid structures on substrate surfaces, (b) incorporation of biologically active molecules (BAM) into such systems, and (c) biological characteristics of the resulting surfaces in vitro and in vivo. Sterilizations issues, important for potential clinical applications, are also considered.

* Engineering Membranes for Bone Regeneration

This review is focused on the use of membranes for the specific application of bone regeneration. The first section focuses on the relevance of membranes in this context and what are the specifications that they should possess to improve the regeneration of bone. Afterward, several techniques to engineer bone membranes by using "bulk"-like methods are discussed, where different parameters to induce bone formation are disclosed in a way to have desirable structural and functional properties. Subsequently, the production of nanostructured membranes using a bottom-up approach is discussed by highlighting the main advances in the field of bone regeneration. Primordial importance is given to the promotion of osteoconductive and osteoinductive capability during the membrane design. Whenever possible, the films prepared using different techniques are compared in terms of handability, bone guiding ability, osteoinductivity, adequate mechanical properties, or biodegradability. A last chapter contemplates membranes only composed by cells, disclosing their potential to regenerate bone.

Effects of VEGF-loaded chitosan coatings

Vascular endothelial growth factor (VEGF) is a powerful growth factor that promotes vascularization as well as osteoblastic differentiation and bone regeneration, all of which are key processes in the osseointegration of dental implants. Strategies to increase vascularization through delivery of VEGF may improve osseointegration, especially in patients with reduced bone healing potential. The aim of this study was to determine the potential of chitosan coatings on titanium to deliver VEGF and to support growth and matrix production of osteoblastic cells in vitro. Chitosan was chemically bonded to titanium coupons via silane-glutaraldehyde linker molecules and loaded with 0, 20, 50, or 100 ng of VEGF. Protein was released during a three day period with around 75% of VEGF (4.44, 11.37, and 22.10 ng/mL/cm(2) from the 20, 50, and 100 ng loaded levels, respectively) released during the first 12 h, and 90-95% of the VEGF released from the coatings by day 3. Saos-2 bone cells continued to proliferate over the 28-day period on the VEGF-loaded chitosan coatings in contrast to cells seeded on uncoated titanium, which plateaued after 14 days. Cells on uncoated titanium exhibited a peak in alkaline phosphatase expression at approximately 14 days, concomitant with the plateau in growth. While osteoblast-like cells on all chitosan coatings exhibited up to a 2-fold enhancement of the alkaline phosphatase activity and 10-fold increase in calcium deposition compared to uncoated controls, the incorporation of VEGF into the coatings did not enhance osteoblast matrix production over plain chitosan coatings throughout this study.

Loading of VEGF to the heparin cross-linked demineralized bone matrix improves vascularization of the scaffold

Deficient vascularization is one of the prominent shortcomings of porous tissue-engineering scaffolds, which results in insufficient oxygen and nutrients transportation. Here, heparin cross-linked demineralized bone matrices (HC-DBM) pre-loaded with vascular endothelial growth factor (VEGF) were designed to promote cells and new microvessels invasion into the matrices. After being chemical crosslinked with heparin by N-hydroxysuccinimide and N-(3-di-methylaminopropyl)-N'-ethylcarbodiimide, the scaffold could bind more VEGF than the non-crosslinked one and achieve localized and sustained delivery. The biological activity of VEGF binding on heparinized collagen was demonstrated by promoting endothelial cells proliferation. Evaluation of the angiogenic potential of heparinized DBM loaded with VEGF was further investigated by subcutaneous implantation. Improved angiogenesis of heparinized DBM loaded with VEGF was observed from haematoxylin-eosin staining and immunohistochemistry examination. The results demonstrated that heparin cross-linked DBM binding VEGF could be a useful strategy to stimulate cells and blood vessels invasion into the scaffolds.

Postdiffusion of oligo-peptide within exponential growth multilayer films for localized peptide delivery

The multilayers of poly(L-lysine) (PLL) and hyaluronic acid (HA) were constructed by alternating deposition of PLL at high pH and HA at low pH. The exponential growth of the multilayer was proved to be amplified by increasing the pH difference between the two deposition solutions. The exponential growth multilayers of PLL/HA assembled at different pH were utilized as reservoirs for loading a trans-activating transcriptional factor (TAT) peptide. The confocal laser scanning microscopy (CLSM) results indicated that the FITC-labeled TAT could diffuse throughout the exponentially growing PLL/HA film. The amount of peptide embedded within multilayer could be adjusted by both multilayer assembly pH and the TAT loading pH. Compared with (PLL/HA 6.5/6.5)5 multilayer (PLL/HA a/b means that the multilayer film was constructed by using PLL at pH a and HA at pH b), the (PLL/HA 9.5/2.9)5 film can be loaded with more TAT peptide at the same loading pH 6.5. The excess of positively charged TAT peptide within (PLL/HA 9.5/2.9)5 film could not only be ascribed to its extraordinary thickness but also be attributed to its uncompensated negative charge density enhanced by the pH difference between film buildup and peptide loading process. Increasing of the TAT loading pH from 6.5 to 9.5, which increases the pH difference between multilayer assembly and peptide loading process, enhances the uncompensated charge density within (PLL/HA 9.5/2.9)5 film and elevates the peptide density from 13.8 to 25.0 microg/cm2. Compared with direct layer-by-layer assembly of TAT and HA, the postdiffusion of TAT into (PLL/HA 9.5/2.9)5 film was loaded much more peptide. The postdiffusion of peptide into a rapid growth multilayer can be more favorable to load and sustainedly release functional oligo-peptide. The cell culture results indicated that the TAT embedded within the film maintained the ability to traverse across the Hep G2 cell membrane. The functionalized (PLL/HA 9.5/2.9)5 TAT 9.5 film was more efficient than the equivalent amount of free TAT peptide in the TAT uptake test. The postdiffusion of oligo-peptide within an exponential growth multilayer can serve as an effective approach for localized and sustained peptide delivery.

Applied chemistry of natural DNA

Recently, natural DNA has emerged as an appealing biomacromolecule for functional materials. It is abundant and renewable, and possesses the well known double helix structure that promises many unique properties difficult to find in other polymers. Natural DNA has been applied in electronic, optical and biomaterials, as a catalyst for enantioselective reactions, and as a material for cleaning the environment. Most of the applications are based on combining DNA with other chemicals or nanoparticles by electrostatic binding, intercalation or groove binding. In this critical review article, recent developments in utilizing natural DNA are reviewed by focusing on three basic properties of DNA: the electrostatic property as a polyelectrolyte, selective affinity for small molecules, and biocompatibility (128 references).

DNA-Coatings: Bioactive Properties and Effects on Osteoblast-Like Cells

The aim of this study was to evaluate potential effects of DNA-coatings on calcium phosphate (CaP) nucleation from simulated body fluids (SBF) and subsequently the effects of DNA-coatings and SBF-immersed DNA coatings on the behavior of osteoblast-like cells. DNAcoatings demonstrated to enhance the nucleation and deposition of CaP from SBF compared to titanium controls. The behavior of osteoblast-like cells was affected on SBF-immersed DNAcoatings, showing an increased deposition of the extracellular matrix protein osteocalcin compared to titanium controls. These results indicate bone-bonding capacity of DNA-coatings, which needs to be confirmed using future animal experiments.

Recent advances in continuous glucose monitoring: biocompatibility of glucose sensors for implantation in subcutis

Tight glycemic control slows or prevents the development of short- and long-term complications of diabetes mellitus. Continuous glucose measurements provide improved glycemic control and potentially prevent these diabetic complications. Glucose sensors, especially implantable devices, offer an alternative to classical self-monitored blood glucose levels and have shown promising glucose-sensing properties. However, the ultimate goal of implementing the glucose sensor as the glucose-sensing part of a closed loop system (artificial pancreas) is still years ahead because of malfunctions of the implanted sensor. The malfunction is partly a consequence of the subcutaneous inflammatory reaction caused by the implanted sensor. In order to improve sensor measurements and thereby close the loop, it is crucial to understand what happens at the tissue-sensor interface.