A tutorial translation of the description of the historically first polymer drug conjugate and its in vivo evaluation

Mezcaline hydrochloride, glycyl-L-leucylmezcalin hydrochloride and a polymer conjugate of glycyl-L-leucyl-mezcaline to a copolymer of vinylpyrrolidone and acrylic acid (P(VP-co- AA)) was injected s.c. and i.p. At different time intervals, the basic degradation product (mezcaline) in the urine was quantified. The injected amount of mezcaline was equal (1.7 mg) in all groups, so that the excretion of mezcaline correlates with the residence time of the biogenic amine in the organism. While the two low molar mass compounds were excreted within 16 h, mezcaline could be detected even after 17 days after s. c. administration of the mezcaline-peptide-polymer conjugate. These findings are viewed in the light of pharmacology, pharmacy, biochemistry and psychiatry. Mezcaline, the biogenic amine found in several cacti, is well known to cause psychological changes after administration to healthy humans which are similar to those found in some psychoses [11]. Block and coworkers found that a fraction of the applied mezcaline is incorporated into a liver protein [3, 4]. About 80% of the applied dose is excreted via renal excretion unmetabolized, as bothmice and human canmetabolizemezcaline only poorly. The product of the incorporation into the liver proteins was not isolated nor characterized in more detail. Inspired by this investigationwe have prepared a peptidedrug conjugate - glycyl-L-leucyl-mezcaline, as described previously [12]. Furthermore, to make it more protein-like, we have covalently conjugated it to a colloidal plasma expander, namely a copolymer of vinylpyrrolidone and acrylic acid (P(VP-co-AA)) with a broad molar mass distribution.10 Both peptamine as well as the polymer conjugate (I, see Scheme 3) were synthesized to gaininsight into the biochemical behavior of peptide-like conjugates of native/biogenic physiologically active compounds of the primary amine type.11 It was assumed that I may represent a novel depot form for primary amines. In the present, second communication, this hypothesis is being tested and fully verified. The hypothesis is based on the fact that I is a conjugate of a non-physiological, high molar mass carrier which guarantees a long residence time in the organism, to which the active compound is bound via a physiological linker, i. e. a dipeptide. The active compound should therefore be enzymatically released in the living organism, if the peptamine is cleaved in vivo.12 To investigate this, white mice were injected s.c. and i.p. with i) 2 mg of mezcaline hydrochloride (mez-HCl), ii) 3.4 mg (glycyl-L-leucyl-mezcaline-hydrochloride (gly-leumez-HCl), iii) a mixture of the macromolecular carrier (P(VP-co-AA)) (16 mg) and 3.4 mg of gly-leu-mez-HCl, iv) 20 mg of the macromolecular carrier with a biodegradable linker (I) and v) 24mgof a conjugate with a non-degradable linker (P(VP-co-AA-co-mez)).13 All substances yield clear solutions in water at neutral pH. The amount injected was chosen so that all animals received 1.7 mg mezcaline. The basic excretion products in the animal's urine were analyzed at different time intervals, for which we used the paper chromatographic analysis method for basic addictive drugs developed by us [13]. This method is not quantitative but does reflect the quantitative ratio [between different groups] well, if all parameters are kept constant.Peer reviewe

A Transient Initiator for Polypeptoids Postpolymerization alpha-Functionalization via Activation of a Thioester Group

Here, a postpolymerization modification method for an alpha-terminal functionalized poly-(N-methyl-glycine), also known as polysarcosine, is introduced. 4-(Methylthio)phenyl piperidine-4-carboxylate as an initiator for the ring-opening polymerization of N-methyl-glycine-N-carboxyanhydride followed by oxidation of the thioester group to yield an alpha-terminal reactive 4-(methylsulfonyl)phenyl piperidine-4-carboxylate polymer is utilized. This represents an activated carboxylic acid terminus, allowing straightforward modification with nucleophiles under mild reaction conditions and provides the possibility to introduce a wide variety of nucleophiles as exemplified using small molecules, fluorescent dyes, and model proteins. The new initiator yielded polymers with well-defined molar mass, low dispersity, and high end-group fidelity, as observed by gel permeation chromatography, nuclear magnetic resonance spectroscopy, and matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy. The introduced method can be of great interest for bioconjugation, but requires optimization, especially for protein conjugation.Peer reviewe

Crosslinking of hydrophilic polymers using polyperoxides

Hydrogels that can mimic mechanical properties and functions of biological tissue have attracted great interest in tissue engineering and biofabrication. In these fields, new materials and approaches to prepare hydrogels without using toxic starting materials or materials that decompose into toxic compounds remain to be sought after. Here, we report the crosslinking of commercial, unfunctionalized hydrophilic poly(2-ethyl-2-oxazoline) using peroxide copolymers in their melt. The influence of temperature, peroxide copolymer concentration, and duration of the crosslinking process has been investigated. The method allows to create hydrogels from unfunctionalized polymers in their melt and to control the mechanical properties of the resulting materials. The design of hydrogels with a suitable mechanical performance is of crucial importance in many existing and potential applications of soft materials, including medical applications.Peer reviewe

Highly Porous and Drug-Loaded Amorphous Solid Dispersion Microfiber Scaffolds of Indomethacin Prepared by Melt Electrowriting

Melt electrowriting (MEW) is an additive manufacturing technology enabling the production of highly porous microfiber scaffolds, suggested in particular for use in biomedical applications, including drug delivery. Indomethacin (IND) is a nonselective anti-inflammatory drug, for which sublingual delivery could offer advantages such as rapid absorption by the veins in the mouth floor while overcoming the side effects of peroral delivery such as damage to the gastrointestinal mucosa barrier. This study introduces MEW as a processing method to obtain rapid-dissolving drug-releasing scaffolds, containing IND as a model drug, for sublingual drug delivery applications. For this, an amorphous solid dispersion (ASD) of IND in combination with a poly(2-oxazoline)-based amphiphilic triblock copolymer excipient is introduced, enabling ultra-high drug loading. We prepared highly porous, melt electrowritten drug-loaded scaffolds with different polymer/IND w/w ratios up to 1:2 and assessed their morphology, amorphicity, and IND release rate. The results show completely amorphous dispersion of the polymer and drug after MEW processing resulting in smooth and uniform fibers and rapid dissolution of the drug loaded scaffold. These first water-soluble melt electrowritten IND-loaded microfiber scaffolds break ground as a model for rapid sublingual delivery of ultra-high drug-loaded ASDs.Peer reviewe

Development of polymer-based nanoparticles for Zileuton delivery to the lung : PMeOx and PMeOzi surface chemistry reduces interactions with mucins

In this paper, two amphiphilic graft copolymers were synthesized by grafting polylactic acid (PLA) as hydrophobic chain and poly(2-methyl-2-oxazoline) (PMeOx) or poly(2-methyl-2-oxazine) (PMeOzi) as hydrophilic chain, respectively, to a backbone of α,β-poly(N-2-hydroxyethyl)-D,L-aspartamide (PHEA). These original graft copolymers were used to prepare nanoparticles delivering Zileuton in inhalation therapy. Among various tested methods, direct nanoprecipitation proved to be the best technique to prepare nanoparticles with the smallest dimensions, the narrowest dimensional distribution and a spherical shape. To overcome the size limitations for administration by inhalation, the nano-into-micro strategy was applied, encapsulating the nanoparticles in water-soluble mannitol-based microparticles by spray-drying. This process has allowed to produce spherical microparticles with the proper size for optimal lung deposition, and, once in contact with fluids mimicking the lung district, able to dissolve and release non-aggregated nanoparticles, potentially able to spread through the mucus, releasing about 70% of the drug payload in 24hours.Peer reviewe

Development of a 3D printable and highly stretchable ternary organic-inorganic nanocomposite hydrogel

Hydrogels that can be processed with additive manufacturing techniques and concomitantly possess favorable mechanical properties are interesting for many advanced applications. However, the development of novel ink materials with high intrinsic 3D printing performance has been proven to be a major challenge. Herein, a novel 3D printable organic-inorganic hybrid hydrogel is developed from three components, and characterized in detail in terms of rheological property, swelling behavior and composition. The nanocomposite hydrogel combines a thermoresponsive hydrogel with clay LAPONITE (R) XLG and in situ polymerized poly(N,N-dimethylacrylamide). Before in situ polymerization, the thermogelling and shear thinning properties of the thermoresponsive hydrogel provides a system well-suited for extrusion-based 3D printing. After chemical curing of the 3D-printed constructs by free radical polymerization, the resulting interpenetrating polymer network hydrogel shows excellent mechanical strength with a high stretchability to a tensile strain at break exceeding 550%. Integrating with the advanced 3D-printing technique, the introduced material could be interesting for a wide range of applications including tissue engineering, drug delivery, soft robotics and additive manufacturing in general.Peer reviewe

Melt electrowriting of poly(vinylidene difluoride) using a heated collector

Previous research on the melt electrowriting (MEW) of poly(vinylidene difluoride) (PVDF) resulted in electroactive fibers, however, printing more than five layers is challenging. Here, we investigate the influence of a heated collector to adjust the solidification rate of the PVDF jet so that it adheres sufficiently to each layer. A collector temperature of 110 degrees C is required to improve fiber processing, resulting in a total of 20 fiber layers. For higher temperatures and higher layers, an interesting phenomenon occurred, where the intersection points of the fibers coalesced into periodic spheres of diameter 206 +/- 52 mu m (26G, 150 degrees C collector temperature, 2000 mm/min, 10 layers in x- and y-direction).The heated collector is an important component of a MEW printer that allows polymers with a high melting point to be processable with increased layers.Peer reviewe

Synthesis and Investigation of Chiral Poly(2,4-disubstituted-2-oxazoline)-Based Triblock Copolymers, Their Self-Assembly, and Formulation with Chiral and Achiral Drugs

Considering the largely chiral nature of biological systems, there is interest in chiral drug delivery systems. Here, we investigate for the first time polymer micelles based on poly(2-oxazoline) (POx) ABA-type triblock copolymers with chiral and racemic hydrophobic blocks for the formulation of chiral and achiral drugs. Specifically, poly(2-ethyl-4-ethyl-2oxazoline) (pEtEtOx) and poly(2-propyl-4-methyl-2-oxazoline) (pPrMeOx) were used as hydrophobic block B and poly(2-methyl-2-oxazoline) (pMeOx) as hydrophilic block A. Using these triblock copolymers, nanoformulations of curcumin (CUR), paclitaxel (PTX), and chiral (R and S) and racemic ibuprofen were prepared. For CUR and PTX, the maximum drug loading was significantly dependent on the structure of the hydrophobic repeat units, but not the chirality. In contrast, the maximum drug loading with chiral/racemic ibuprofen was affected neither by the polymer structure nor by chirality, but minor effects were observed with respect to the size and size distribution of the drug-loaded micelles.Peer reviewe

Stages of neuronal network formation

Graph theoretical approaches have become a powerful tool for investigating the architecture and dynamics of complex networks. The topology of network graphs revealed small-world properties for very different real systems among these neuronal networks. In this study, we observed the early development of mouse retinal ganglion cell (RGC) networks in vitro using timelapse video microscopy. By means of a time-resolved graph theoretical analysis of the connectivity, shortest path length and the edge length, we were able to discover the different stages during the network formation. Starting from single cells, at the first stage neurons connected to each other ending up in a network with maximum complexity. In the further course, we observed a simplification of the network which manifested in a change of relevant network parameters such as the minimization of the path length. Moreover, we found that RGC networks self-organized as small-world networks at both stages; however, the optimization occurred only in the second stage

Quantifying surface properties of silica particles by combining Hansen Parameters and Reichardt's Dye indicator data

To obtain quantitative understanding of the effects of a chemisorbed organic modification on the surface of particles, the use of Reichardt's dye (RD) and Hansen solubility parameter (HSP) is discussed, whereby the S should be understood in terms of “similarity” rather than solubility as dispersibility is in focus. Silica nanoparticles modified to different extents with a medium chain silane including completely hydrophilic and hydrophobic particles are chosen. During spray‐drying such particles form fully redispersible micro‐raspberry superstructures. After qualitative estimations of the particles' polarity based on measuring both immersion time and ability of modified particles to stabilize oil–water emulsions, surface properties are quantified by HSP and RD. With increasing hydrophobicity, i.e., increasing amount of silane at the surface, all three contributions to HSP change. At the same time, RD analysis reveals that the normalized solvent polarity parameter decreases progressively. HSP and RD analysis are in good agreement, giving strong confidence on each method applied individually. This work demonstrates that after noticeable attempts for combined solubility parameters in case of molecules, carbon allotropes, and gelators, such studies can be extended toward functional (nano)particles and that a full picture of particle surface properties is possible via the combination of different, quantitative techniques