Branched Amino Acid Based Poly(ester urea)s with Tunable Thermal and Water Uptake Properties

A series of amino-acid based poly­(ester urea)­s (PEU) with controlled amounts of branching was synthesized and characterized. The mechanical properties, thermal characteristics and water absorptions varied widely with the extent of branch unit incorporation. Herein, the details of the synthesis of a linear bis­(l-phenylalanine)-hexane 1,6-diester monomer, a branch tri-<i>O</i>-benzyl-l-tyrosine-1,1,1-trimethylethane triester monomer and a series of copolymers are described. The extent of branching was varied by adjusting the molar ratio of linear to branched monomer during the interfacial polymerization. The elastic moduli span a range of values (1.0–3.1 GPa) that overlaps with several clinically available degradable polymers. Increasing the amount of branching monomers reduces the molecular entanglement, which results in a decrease in elastic modulus values and an increase in values of elongation at break. The l<i>-</i>phenylalanine-based poly­(ester urea)­s also exhibited a branch density dependent water uptake ability that varied between 2 and 3% after 24 h of immersion in water. Nanofibers incorporating 8% branching were able to maintain their morphology at elevated temperature, in hydrated conditions, and during ethylene oxide sterilization which are critical to efforts to translate these materials to clinical soft tissue applications

Y Shape Osteotomy in Ankylosing Spondylitis, a Prospective Case Series with Minimum 2 Year Follow-Up

<div><p>The aim of the study is to evaluate the efficacy of a spinal osteotomy technique, Y shape osteotomy, for correcting kyphosis in AS patients planned preoperatively with computer software-assistance. 36 consecutive AS patients with thoracolumbar kyphosis were treated with one-stage posterior Y shape osteotomy and preoperative surgical planning was done with the aid of the Surgimap Spine. Radiological parameters of simulation and immediate postoperation were documented. Clinical and radiological results were evaluated in the preoperative, the early postoperative periods and during the last follow-up. The lumbar lordosis was found as 40.7 ± 4.1 degrees in the surgical planning and 49.7 ± 3.9 degrees postoperatively (p<0.01). PI-LL was 3.8± 0.9°in the simulation procedure and 6.6± 1.5°postoperatively (p<0.01). At the final follow-up, Global sagittal balance was restored and Both Oswestry Disability Index and Scoliosis Research Society scores improved largely. In conclusion, Y shape osteotomy is a safe and effective treatment option for AS patients with kyphosis deformity.</p></div

The simulation of Y shape osteotomy in surgimap for patients with AS.

<p>(A) Spino- pelvic parameters were measured and analyzed; (B) “Wedge Osteotomy” was applied at the posterior column of L2; (C) radiographic image after simulated osteotomy.</p

Y shape osteotomy.

<p>(A) ‘Y’ type osteotomy was achieved; (B) the posterior wedge space was closed with appropriate opening of the anterior column; (C) intra-operative imaging shows L1 Y shape osteotomy</p

Pre- and post-operative radiological outcomes.

<p>(A, B, C) AP and lateral standing radiographs and sagittal CT scan of a 36-year-old man with thoracolumbar kyphosis secondary to ankylosing spondylitis; (D, E, F): Y shape osteotomy was performed at L2, and Two years of follow-up revealed the normal sagittal alignment was achieved.</p

The preoperative and last follow-up data of patients with AS.

<p>The preoperative and last follow-up data of patients with AS.</p

Cascading “Triclick” Functionalization of Poly(caprolactone) Thin Films Quantified via a Quartz Crystal Microbalance

A series of mono- and multifunctionalized degradable polyesters bearing various “clickable” groups, including ketone, alkyne, azide, and methyl acrylate (MA) are reported. Using this approach, we demonstrate a cascade approach to immobilize and quantitate three separate bioactive groups onto poly­(caprolactone) (PCL) thin films. The materials are based on tunable copolymer compositions of ε-caprolactone and 2-oxepane-1,5-dione. A quartz crystal microbalance (QCM) was used to quantify the rate and extent of surface conjugation between RGD peptide and polymer thin films using “click” chemistry methods. The results show that alkyne-functionalized polymers have the highest conversion efficiency, followed by MA and azide polymers, while polymer films possessing keto groups are less amenable to surface functionalization. The successful conjugation was further confirmed by static contact angle measurements, with a smaller contact angle correlating directly with lower levels of surface peptide conjugation. QCM results quantify the sequential immobilization of peptides on the PCL thin films and indicate that Michael addition must occur first, followed by azide–alkyne Huisgen cycloadditions

The patient is placed prone on a radiolucent operating table

<p>The patient is placed prone on a radiolucent operating table</p

Patient demographics.

<p>Patient demographics.</p

Three-Dimensional Printing of Nano Hydroxyapatite/Poly(ester urea) Composite Scaffolds with Enhanced Bioactivity

Polymer–bioceramic composites incorporate the desirable properties of each material while mitigating the limiting characteristics of each component. 1,6-Hexanediol l-phenylalanine-based poly­(ester urea) (PEU) blended with hydroxyapatite (HA) nanocrystals were three-dimensional (3D) printed into porous scaffolds (75% porosity) via fused deposition modeling and seeded with MC3T3-E1 preosteoblast cells in vitro to examine their bioactivity. The resulting 3D printed scaffolds exhibited a compressive modulus of ∼50 MPa after a 1-week incubation in PBS at 37 °C, cell viability >95%, and a composition-dependent enhancement of radio-contrast. The influence of HA on MC3T3-E1 proliferation and differentiation was measured using quantitative real-time polymerase chain reaction, immunohistochemistry and biochemical assays. After 4 weeks, alkaline phosphatase activity increased significantly for the 30% HA composite with values reaching 2.5-fold greater than the control. Bone sialoprotein showed approximately 880-fold higher expression and 15-fold higher expression of osteocalcin on the 30% HA composite compared to those of the control. Calcium quantification results demonstrated a 185-fold increase of calcium concentration in mineralized extracellular matrix deposition after 4 weeks of cell culture in samples with higher HA content. 3D printed HA-containing PEU composites promote bone regeneration and have the potential to be used in orthopedic applications