Jens Christoph Thies

A virus-based biocatalyst

Virus particles are probably the most precisely defined nanometre-sized objects that can be formed by protein self-assembly. Although their natural function is the storage and transport of genetic material, they have more recently been applied as scaffolds for mineralization and as containers for the encapsulation of inorganic compounds. The reproductive power of viruses has been used to develop versatile analytical methods, such as phage display, for the selection and identification of (bio)active compounds. To date, the combined use of self-assembly and reproduction has not been used for the construction of catalytic systems. Here we describe a self-assembled system based on a plant virus that has its coat protein genetically modified to provide it with a lipase enzyme. Using single-object and bulk catalytic studies, we prove that the virus-anchored lipase molecules are catalytically active. This anchored biocatalyst, unlike man-made supported catalysts, has the capability to reproduce itself in vivo, generating many independent catalytically active copies.

Polymers in Cartilage Defect Repair of the Knee: Current Status and Future Prospects

Cartilage defects in the knee are often seen in young and active patients. There is a need for effective joint preserving treatments in patients suffering from cartilage defects, as untreated defects often lead to osteoarthritis. Within the last two decades, tissue engineering based techniques using a wide variety of polymers, cell sources, and signaling molecules have been evaluated. We start this review with basic background information on cartilage structure, its intrinsic repair, and an overview of the cartilage repair treatments from a historical perspective. Next, we thoroughly discuss polymer construct components and their current use in commercially available constructs. Finally, we provide an in-depth discussion about construct considerations such as degradation rates, cell sources, mechanical properties, joint homeostasis, and non-degradable/hybrid resurfacing techniques. As future prospects in cartilage repair, we foresee developments in three areas: first, further optimization of degradable scaffolds towards more biomimetic grafts and improved joint environment. Second, we predict that patient-specific non-degradable resurfacing implants will become increasingly applied and will provide a feasible treatment for older patients or failed regenerative treatments. Third, we foresee an increase of interest in hybrid construct, which combines degradable with non-degradable materials.

Celecoxib-loaded PEA microspheres as an auto regulatory drug-delivery system after intra-articular injection

In this study, we investigated the potential of celecoxib-loaded polyester amide (PEA) microspheres as an auto-regulating drug delivery system for the treatment of pain associated with knee osteoarthritis (OA). Celecoxib release from PEA microspheres and inflammation responsive release of a small molecule from PEA was investigated in vitro. Inflammation responsive release of a small molecule from PEA was observed when PEA was exposed to cell lysates obtained from a neutrophil-like Hl-60 cell line. Following a short initial burst release of ~15% of the total drug load in the first days, celecoxib was slowly released throughout a period of >80days. To investigate biocompatibility and degradation behavior in vivo, celecoxib-loaded PEA microspheres were injected in OA-induced (ACLT+pMMx) or contralateral healthy knee joints of male Lewis rats. Bioactivity of celecoxib from loaded PEA microspheres was confirmed by PGE2 measurements in total rat knee homogenates. Intra-articular biocompatibility was demonstrated histologically, where no cartilage damage or synovial thickening and necrosis were observed after intra-articular injections with PEA microspheres. Degradation of PEA microspheres was significantly higher in OA induced knees compared to contralateral healthy knee joints, while loading the PEA microspheres with celecoxib significantly inhibited degradation, indicating a drug delivery system with auto regulatory behavior. In conclusion, this study suggests the potential of celecoxib-loaded PEA microspheres to be used as a safe drug delivery system with auto regulatory behavior for treatment of pain associated with OA of the knee.

Optical and electroemission properties of thin films of supermolecular anthracene-based rotaxanes

Rotaxanes are a new class of functional materials. They consist of mechanically interlocked supermolecular systems where a central linear thread passes through the cavity of a macrocyclic ring. The ring is constrained within the two extremities of the thread by two bulky stoppers. In this work, we report on spectroscopic characterisation of an anthracene-based novel rotaxane (EPAR-Me) and on the electroemission (EL) from a basic rotaxane component (ANTPEP). An OLED has been prepared using the anthracene-based thread (ANTPEP) of the EPAR-Me rotaxane in polycarbonate matrices. Spectroscopic measurements are reported, supporting excimer-like EL and field dependent electroexcimer for the ANTPEP thin film. Tentative assignment of emitting species of EPAR-Me are also discussed.

Thermodynamic investigation of Z33-antibody interaction leads to selective purification of human antibodies

Antibodies, such as IgGs, are widely applied as detection probes, purification ligands and targeting moieties in research and medicine. Protein A from Staphylococcus aureus is capable of selectively binding to antibodies. Z33, a 33 amino acid peptide sequence derived from Protein A, is a minimized binding domain with comparable interaction potential. This peptide was fused to two different proteins without perturbing the properties of both the protein and the Z33-domain. The thermodynamic parameters for the interaction of the fusion proteins with antibodies from various species were determined by isothermal titration calorimetry. This showed that binding was enthalpically driven and entropically unfavorable. A difference in Z33 binding affinity of several orders of magnitude was observed between human and bovine antibodies. This selectivity toward human IgGs was utilized for the efficient and selective purification of human IgGs from mixtures containing bovine IgGs and other proteins by affinity precipitation employing a fusion protein of Z33 and a stimulus-responsive elastin-like polypeptide.

Photophysical properties of thin films and solid phase of switchable supermolecular anthracene-based rotaxanes

Polycrystalline powders and thin films of a novel rotaxane, methyl-exopyridine-anthracene rotaxane (EPAR-Me), and of the related thread and stoppers 10-[3,5-di (ter butyl)phenoxy]decyl-2-({2-[(9-anthrylcarbonyl) amino] acetyl}amino) acetate (ANTPEP), have been characterised by photoluminescence, absorption and photoluminescence excitation spectroscopy. A rather unusual, i.e. unstructured and largely red-shifted, photoluminescence spectral behaviour of the rotaxane has been found. Preliminary time resolved measurements indicate a fast energy transfer from the anthracene unit to different species the nature of which is still not assigned.

Prolonged inhibition of inflammation in osteoarthritis by triamcinolone acetonide released from a polyester amide microsphere platform

&NA; Controlled biomaterial‐based corticosteroid release might circumvent multiple injections and the accompanying risks, such as hormone imbalance and muscle weakness, in osteoarthritic (OA) patients. For this purpose, microspheres were prepared from an amino acid‐based polyester amide (PEA) platform and loaded with triamcinolone acetonide (TAA). TAA loaded microspheres were shown to release TAA for over 60 days in PBS. Furthermore, the bioactivity lasted at least 28 days, demonstrated by a 80–95% inhibition of PGE2 production using TNF&agr;‐stimulated chondrocyte culture, indicating inhibition of inflammation. Microspheres loaded with the near infrared marker NIR780‐iodide injected in healthy rat joints or joints with mild collagenase‐induced OA showed retention of the microspheres up till 70 days after injection. After intra‐articular injection of TAA‐loaded microspheres, TAA was detectable in the serum until day seven. Synovial inflammation was significantly lower in OA joints injected with TAA‐loaded microspheres based on histological Krenn scores. Injection of TAA‐loaded nor empty microspheres had no effect on cartilage integrity as determined by Mankin scoring. In conclusion, the PEA platform shows safety and efficacy upon intra‐articular injection, and its extended degradation and release profiles compared to the currently used PLGA platforms may render it a good alternative. Even though further in vivo studies may need to address dosing and readout parameters such as pain, no effect on cartilage pathology was found and inflammation was effectively lowered in OA joints. Graphical abstract Figure. No caption available.

38.2: High Performance Single Layer Anti‐Reflective Coatings via Wet UV Curing Technology

Here we present a novel manner for preparing single layer anti-reflective coatings with excellent optical properties (<1% reflection) over a broad wavelength regime. The technology is based upon the self-assembly and UV curing of reactive nano-particles, leading to nano-structured coatings with a gradient in refractive index. The single processing step leading to such coatings is fast, robust and cost effective.

Intradiscal delivery of celecoxib-loaded microspheres restores intervertebral disc integrity in a preclinical canine model

ABSTRACT Low back pain, related to degeneration of the intervertebral disc (IVD), affects millions of people worldwide. Clinical studies using oral cyclooxygenase‐2 (COX‐2) inhibitors have shown beneficial effects, although side‐effects were reported. Therefore, intradiscal delivery of nonsteroidal anti‐inflammatory drugs can be an alternative treatment strategy to halt degeneration and address IVD‐related pain. In the present study, the controlled release and biologic potency of celecoxib, a selective COX‐2 inhibitor, from polyesteramide microspheres was investigated in vitro. In addition, safety and efficacy of injection of celecoxib‐loaded microspheres were evaluated in vivo in a canine IVD degeneration model. In vitro, a sustained release of celecoxib was noted for over 28 days resulting in sustained inhibition of inflammation, as indicated by decreased prostaglandin E2 (PGE2) production, and anti‐catabolic effects in nucleus pulposus (NP) cells from degenerated IVDs on qPCR. In vivo, there was no evidence of adverse effects on computed tomography and magnetic resonance imaging or macroscopic evaluation of IVDs. Local and sustained delivery of celecoxib prevented progression of IVD degeneration corroborated by MRI, histology, and measurement of NP proteoglycan content. Furthermore, it seemed to harness inflammation as indicated by decreased PGE2 tissue levels and decreased neuronal growth factor immunopositivity, providing indirect evidence that local delivery of a COX‐2 inhibitor could also address pain related to IVD degeneration. In conclusion, intradiscal controlled release of celecoxib from polyesteramide microspheres prevented progression of IVD degeneration both in vitro and in vivo. Follow‐up studies are warranted to determine the clinical efficacy of celecoxib‐loaded PEAMs in chronic back pain. Graphical abstract Figure. No caption available.

Solid-state optical properties of the methyl-exopyridine-anthracene rotaxane

Photophysical properties in the solid state of both, an anthracene grafted rotaxane and the corresponding thread are studied. The thread in liquid and solid states as well as the rotaxane in the liquid phase exhibit only the usual anthracene-like photoluminescence (PL) behaviour, while the rotaxane polycrystalline powder emits a broad structureless red-shifted band. The excitation spectrum of the rotaxane reveals the presence of low-lying states below the absorption feature of the anthracene, the one of the thread reproducing quite accurately the absorption spectrum. Site-selective PL measurements show that the broad emission of the rotaxane is a superposition of two contributions corresponding to energy levels which can be photoexcited directly within the low energy absorption tail. Time resolved PL measurements reveals immediately after excitation the characteristic features of the anthracene-like emission, indicating an energy transfer from the excited anthracene moiety to the structural defect states giving rise to the unusual radiative emission.