<p>Juvenile nucleus pulposus (NP) cells of the intervertebral disc (IVD) are large, vacuolated cells that form cell clusters with numerous cell-cell interactions. With maturation and aging, NP cells lose their ability to form these cell clusters, with associated changes in NP cell phenotype, morphology and proteoglycan synthesis that may contribute to IVD degeneration. Studies demonstrate healthy, juvenile NP cells exhibit potential for preservation of multi-cell clusters and NP cell phenotype when cultured upon soft, laminin-containing substrates; however, the mechanisms that regulate metabolism and phenotype of these NP cells are not understood. N-cadherin is a cell adhesion molecule that is present in juvenile NP cells, but disappears with age. The goal of this dissertation was to reveal the role of N-cadherin for NP cells in multi-cell clusters that contribute to the maintenance of the juvenile NP cell morphology and phenotype in vitro, and to evaluate the potential for laminin- functionalized poly(ethylene glycol) (PEG-LM) hydrogels to promote human NP cells towards a juvenile NP cell phenotype. </p><p>In this dissertation, juvenile porcine IVD cells were promoted to form cell clusters in vitro, and analyzed for preservation of the juvenile NP phenotype on soft, laminin-rich hydrogels. In the first part of this dissertation, preservation of the porcine juvenile NP cell phenotype and presence of N-cadherin was analyzed by culturing porcine NP cells on soft, laminin-rich or PEG-LM hydrogels. Secondly, cadherin-blocking experiments were performed to prevent cluster formation in order to study the importance of cluster formation in NP cell signaling. Finally, human IVD cells were cultured on PEG-LM hydrogels to investigate the potential to revert degenerate, human NP cells toward a juvenile NP cell phenotype and morphology. </p><p>Findings reveal soft (<500 Pa), laminin-rich substrates promote NP cell clustering, a key feature of the juvenile NP cell that is associated with N-cadherin positive expression. Additionally, N-cadherin-mediated cell-clustering regulates NP cell matrix production and gene expression of NP-specific and NP-matrix related markers. Inhibition of N-cadherin-mediated contacts resulted in decreased expression of juvenile NP cell features. Finally, juvenile human NP cells are also able to form N-cadherin positive cell clusters on soft, PEG-LM hydrogels with higher expression of juvenile NP cell features compared to culturing on stiff PEG-LM hydrogels. Some degenerate, human NP cells are also able to form N-cadherin positive cell clusters with some features of the juvenile NP cell. </p><p>The studies presented in this dissertation support the proposed hypothesis and establish the importance of soft, laminin-rich substrates in promoting NP cell clustering behaviors with associated features of a juvenile cell phenotype and morphology. Additionally, these studies establish a regulatory role for N-cadherin in juvenile NP cells and suggest that preservation of N-cadherin-mediated cell-cell contacts is important for preserving the juvenile NP cell phenotype and morphology. Furthermore, findings from this dissertation reveal the ability to promote degenerate, mature human NP cells towards a juvenile NP cell phenotype, demonstrating the potential to use PEG-LM hydrogels as a means for autologous cell delivery for the restoration of healthy IVD.</p> / Dissertation

Nanopore sensing is a label-free method used to characterize water-soluble molecules. Recent work describes how Au25(SG)18 clusters improve the single molecule nanopore spectrometry (SMNS) technique when analyzing polyethylene glycol (PEG). This thesis will further study and optimize the enhancement effect resulting from a cluster’s presence. Additionally, a model describing the interaction between a cluster and PEG is developed to assist in understanding this mechanism of enhancement. This thesis will also discuss expanding the SMNS method to detect peptides, using Au25(SG)18 for enhancement, and adjusting solution conditions to improve the sensitivity of the SMNS system for peptide detection. Finally, a model describing the relationship between nanopore current blockades and molecular weight is developed to demonstrate the feasibility of using SMNS as a viable analytical technique for characterizing a wide variety of water-soluble molecules.

O presente estudo foi realizado em duas etapas com os seguintes objetivos: (i) avaliar os efeitos da suplementação com leguminosa tropical em comparação ao concentrado em gramínea tropical na ingestão de nutrientes por cordeiros; (ii) avaliar a inclusão de leguminosa tropical em pastagem de gramínea sobre o consumo de nutrientes por cordeiros recebendo polietileno glicol 4000. O delineamento experimental foi em blocos ao acaso e no segundo experimento em parcela subdividida. No primeiro estudo (capítulo III), 72 cordeiros foram alocados em 12 piquetes (0,1 ha cada) de capim Aruana (Panicum maximum cv. IZ-5) e submetidos aos tratamentos por 90 dias: 1) S0,0 – sem suplementação; 2) S1,5 - suplementação com concentrado a 1,5% de PV; 3) S2,5 -suplementação com concentrado a 2,5% PV, 4) SFG - suplementação com pastejo controlado em 0,1 ha de feijão Guandu (Cajanus cajan cv. Anão) por três horas/dia. No segundo experimento (capítulo IV), 54 cordeiros foram alocados em nove piquetes (0,2 ha cada) submetidos aos tratamentos por 84 dias: 1) Aruana – somente capim Aruana; 2) AFG - consórcio de feijão Guandu e capim Aruana, em faixa, 3) Guandu - somente feijão Guandu, cada tratamento foi subdividido em parcelas com e sem PEG (polietileno glicol 4000). No experimento 1, as variáveis de comportamento ingestivo, consumo e digestibilidade de nutrientes foram influenciadas pelos tratamentos (P < 0,05), tendo os cordeiros do grupo S2,5 apresentado melhor ingestão de nutrientes e o grupo SFG consumo intermediário. Em geral, o grupo SFG apresentou resultados semelhantes ao S1,5. No segundo experimento, as variáveis de comportamento ingestivo não foram influenciadas pelos tratamentos e pelo uso do PEG (P > 0,05). Houve interação entre os sistemas de alimentação e uso de PEG para a ingestão de nutrientes e digestibilidade (P > 0,05), com os melhores resultados para os grupos sem PEG (P < 0,05). Em geral, os animais que não receberam PEG e que foi incluído Guandu na dieta, apresentaram aumento no consumo de nutrientes. Assim, o feijão Guandu pode substituir o concentrado em nível de até 1,5% do PV como suplemento para o capim Aruana. A inclusão da leguminosa tropical com presença de taninos condensados favorece o consumo de nutrientes por cordeiros criados em pastagem tropical. / This study was performed in two stages with the following objectives: (i) to evaluate the effects of topical legume supplementation compared with the concentrate in tropical grass in the intake of nutrients by lambs; (ii) to evaluate the inclusion of tropical legume in grass pasture on intake of nutrients for lambs receiving polyethylene glycol 4000 (PEG). A randomized block design was use in the first experiment and split plot design was use in the second experiment. In the first study (Chapter III), 72 lambs were divided into 12 paddocks (0.1 ha each) of Aruana grass de (Panicum maximum cv. IZ-5) and subjected to treatments for 90 days: 1) S0,0 - only Aruana grass; 2) S1.5 - supplementation with concentrated to 1.5% of lamb BW; 3) S2.5 - supplementation with concentrated to 2.5% of lamb BW; 4) SFG – supplementation with controlled grazing on 0.1 ha of pigeon pea (Cajanus cajan cv. Anão) for three h / d. In the second study (Chapter IV), 54 lambs were divided into nine paddocks (0.2 ha each) and subjected to treatments for 84 days: 1) Aruana – only Aruana grass; 2) AFG - consortium with Aruana grass and pigeon pea; 3) Guandu – only pigeon pea, where each treatment was divided into plots with or without PEG (polyethylene glycol 4000). In the experiment 1, the ingestive behavior variables, intake and digestibility of nutrients were affect by treatments (P < 0.05) with the lambs of the group S2.5 presented better intake of nutrients and the group SFG intake intermediate. In general, the SFG group showed similar results to S1.5. In the second experiment, the ingestive behavior variables were not affected by the treatments and the use of PEG (P>0.05). There was interaction between the feeding systems and use of PEG for intake of nutrients and digestibility (P < 0.05), with the best result for the treatments without PEG (P < 0.05). In general, animals that did not receive PEG and that included pigeon pea in the diet, showed an increase in the intake of nutirents. Thus, pigeon pea can substitute the concentrate at a level of 1,5% PV as a supplement for the Aruana grass. The inclusion of the tropical legume with presence of condensed tannin favors the intake of nutrients by lambs raised in tropical pasture.

Made available in DSpace on 2014-06-11T19:30:54Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-08-16Bitstream added on 2014-06-13T20:01:02Z : No. of bitstreams: 1 gaspar_rt_dr_sjrp.pdf: 649983 bytes, checksum: 1fcf82fd9f75312b80b50e055388690d (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / O Poli(etileno glicol) (PEG) é um polímero sintético cujas características tem despertado grande interesse em diversas áreas. Suas aplicações podem ser vistas nas mais variadas áreas, desde biotecnologia e medicina até aplicações industriais e cosméticos. Alguns aspectos físicos como a estrutura adotada por esse polímero em diferentes solventes e detalhes sobre a interação entre essas moléculas ainda necessitam de maiores esclarecimentos, o que o torna objeto de intensa investigação. Essa tese visa desenvolver um modelo para moléculas de PEG, que possa ser utilizado em experimentos de dinâmica molecular. Resultados de simulações com esse modelo foram comparados a dados experimentais presentes na literatura, de forma a verificar o comportamento do modelo em diferentes condições, avaliando assim sua adequação. Os valores de densidade, obtidos dos sistemas simulados, apresentaram erro máximo de 1,14% para concentrações de até 50% de PEG400. A densidade do sistema em função da temperatura concorda com os dados da literatura, mantendo um erro fixo de 0,35%, que está relacionado com a concentração de 50% utilizada nessa simulação. A estrutura helicoidal, apresentada pelas moléculas de PEG ao final do processo de preparação dos modelos, é perdida rapidamente em todas as diferentes condições em que o sistema foi simulado, indicando que tal estrutura é energeticamente desfavorável em água. Com o aumento da concentração de PEG, as seguintes estruturas foram encontradas: moléculas de PEG livres em solução em concentrações inferiores a 5%, aglomerados de PEG entre 5 e 50%, com uma transição gradual entre uma estrutura e outra. Os resultados obtidos para concentrações acima de 50% não são conclusivos. Seguindo o procedimento aplicado ao modelo inicial, de PEG400, foi desenvolvido... / Poly(ethylene glycol) (PEG) is a synthetic polymer whose characteristics have attracted great interest in different fields. It has been applied in very different areas, from biotechnology and medicine to industry and cosmetics. Physical aspects like the structure PEG assumes in different solvent and details on the interaction between these polymers still lack clarity, make PEG an object of intense investigation. This Thesis aims do develop a model for PEG molecules that can be used in molecular dynamic simulations. Results of simulations using this model were compared to published experimental data, in order to investigate the behavior of the model under different conditions to evaluate its validity. The density values obtained from the simulations exhibit a maximum error of 1.14% for PEG400 concentrations up to 50%. The system density as a function of temperature agrees with experimental data from the literature within an error of 0.35% for the 50% PEG in the simulation. The helicoidal structure assumed by the PEG molecules at the end of the procedure of the model preparation is quickly lost under every simulation condition, thus indicating that the helicoidal structure is not energetically favorable for PEG in water. As PEG concentration is increased, the following structures were found: free PEG molecules below ca 5%, PEG clusters from ca 5-50%, with a gradual transition from one structure to another. The results for concentrations higher than 50% are not conclusive. Following the procedure applied to the initial PEG400 model, a second model was developed, almost four times larger, and used to investigate possible molecular effects capable to induce phase thermoseparation. The transition from different system states took place on average temperatures between 423.3 K and 424.1 K at the average pressure of 8.98 Bar.

Thesis (M.Sc. (Agriculture)) --University of Limpopo, 2006 / Two experiments were carried out to determine the effect of the level of Acacia nilotica leaf meal supplementation plus 23 g polyethylene glycol 4000 on diet intake, digestibility, and growth rate of indigenous Pedi goats fed ad libitum Buffalo grass, Buchloe dactyloides, hay. The first experiment lasted for 37 days, with the first 30 days being for adaptation and the last 7 days being for collection. Twenty yearling male Pedi goats weighing 22 ± 0.5 kg live weight were allocated to 4 treatments in a 2 x 2 Factorial arrangement in a Completely Randomised Design. Acacia nilotica leaf meal contained 120 g crude protein per kg DM, indicating its potential as a browse source for ruminants. It, also, contained high amounts of total phenolics (2.04 % DM) and low amounts of condensed tannins, both extracted (0.37 % DM) and unextracted (1.83 % DM). Increasing the level of Acacia nilotica leaf meal supplementation to 120 g increased (P<0.05) crude protein intake (38 g/kg DM) when compared to 80 g supplementation (34 g/kg DM). Supplementation with 23 g PEG 4000 increased (P<0.05) the crude protein intake where goats were supplemented with 120 g of A. nilotica leaf meal. However, PEG 4000 supplementation did not have an effect (P>0.05) on intake when goats were supplemented with 80 g of Acacia nilotica leaf meal. Supplementation with 120 g of Acacia nilotica leaf meal increased (P<0.05) diet digestibility of DM (0.57), OM (0.60) and CP (0.71) by the goats. Similarly, supplementation with 23 g PEG 4000 increased (P<0.05) DM (0.65), OM (0.66) and v CP digestibilities (0.76) where goats were supplemented with 120 g of A. nilotica leaf meal. Polyethylene glycol 4000 also increased (P<0.05) diet CP digestibility where goats were supplemented with 80 g of Acacia nilotica leaf meal. However, 23 g PEG 4000 did not have a significant (P>0.05) effect on diet digestibility of DM and OM where goats were supplemented with 80 g of Acacia nilotica leaf meal. In vivo NDF and ADF digestibility were not affected by the treatments. Level of Acacia nilotica leaf meal supplementation plus 23 g of PEG 4000 had a significant (P<0.05) effect on the daily live weight change of the goats. The effect was higher where goats were supplemented with 120 g of A. nilotica leaf meal when compared to 80 g supplementation. Blood urea concentrations were improved (P<0.05) by level of A. nilotica supplementation and PEG supplementation. It is concluded that PEG 4000 has the potential to improve the feeding value of Acacia nilotica leaf meal and can, therefore, be used in the feeding systems for ruminant animals. The second experiment determined the effect of A. nilotica leaf meal supplementation and PEG 4000 supplementation on in vitro diet digestibility. Level of Acacia nilotica leaf meal supplementation plus 23 g PEG supplementation improved (P<0.05) in vitro diet DM, OM and CP digestibilities where 120 g Acacia nilotica leaf meal was supplemented. Similarly, 23 g PEG 4000 supplementation also improved (P<0.05) in vitro diet CP digestibility where 80 g Acacia nilotica leaf meal was supplemented. However, level of A. nilotica supplementation plus PEG 4000 supplementation had no vi effect (P>0.05) on in vitro NDF and ADF digestibilities. In vivo diet DM, OM and CP digestibilities were positively and significantly (P<0.05) correlated with in vitro diet DM, OM and CP digestibilities. It is, therefore, concluded that in vitro diet DM, OM and CP digestibilities have good capacity to predict in vivo diet DM, OM and CP digestibilities. / National Research Foundation. Working Solutions International

A suitable management of the pharmaceutical property is needed and helpful to design a desired nanoparticulate delivery system, which includes the carrier nature, particle size and size distribution, morphology, surfactant stabiliser according to the technique applied, drug-loading ratio and encapsulation efficiency, surface property, etc. All will influence the in vitro release, in vivo behaviour and tissue distribution of administered particulate drug loaded nanoparticles. The main purpose of the present work was to determine the effect of drug loading ratio when employing TPGS as surfactant stabiliser and/or matrix material to improve the nanoparticulate formulation. The model drug employed was paclitaxel. / Singapore-MIT Alliance (SMA)

Moderne Methoden für die Einzelzellanalyse werden dank der fortschreitenden Weiterentwicklung immer sensitiver. Dabei steigen jedoch auch die Anforderungen an das Probenmaterial. Viele Aufbereitungsprotokolle adhärenter Zellen beinhalten eine enzymatische Spaltung der Oberflächenproteine, um die Ablösung vom Zellkultursubstrat zu ermöglichen. Verschiedene Methoden, wie die Patch-Clamp-Technik oder eine auf der Markierung extrazellulärer Domänen von Membranproteinen basierende Durchflusszytometrie können dann nur noch eingeschränkt eingesetzt werden. Daher ist die Etablierung neuer Zellablösemethoden dringend notwendig. In der vorliegenden Arbeit werden erstmals PEG-basierte thermo-responsive Oberflächen erfolgreich für die Zellkultur eingesetzt. Dabei wird das zerstörungsfreie Ablösen verschiedener Zelllinien von den Oberflächen durch Temperatursenkung realisiert. Die Funktionalität der Oberflächen wird durch Variation der Polymerstruktur, sowie der Konzentration der Beschichtungslösung, durch Beschichtung der Oberflächen mit einem zelladhäsionsfördernden Protein (Fibronektin) und durch Adsorption zelladhäsionsvermittelnder Peptide (RGD) optimiert. Um den Zellablösungsprozess detaillierter zu untersuchen, wird hier zum ersten Mal der direkte Zellkontakt mit thermo-responsiven Oberflächen mittels oberflächensensitiver Mikroskopie (TIRAF) sichtbar gemacht. Mit dieser Technik sind die exakte Quantifizierung und die Analyse der Reduktion der Zelladhäsionsfläche während des Abkühlens möglich. Hierbei werden in Abhängigkeit von der Zelllinie Unterschiede im Zellverhalten während des Ablösens festgestellt: Zellen, wie eine Brustkrebszelllinie und eine Ovarzelllinie, die bekanntermaßen stärker mit ihrer Umgebung in Kontakt treten, vergrößern im Verlauf des Beobachtungszeitraumes den Abstand zwischen Zellmembran und Oberfläche, reduzieren jedoch ihre Zell-Substratkontaktfläche kaum. Mausfibroblasten hingegen verkleinern drastisch die Zelladhäsionsfläche. Der Ablösungsprozess wird vermutlich aktiv von den Zellen gesteuert. Diese Annahme wird durch zwei Beobachtungen gestützt: Erstens verläuft die Reduktion der Zelladhäsionsfläche bei Einschränkung des Zellmetabolismus durch eine Temperatursenkung auf 4 °C verzögert. Zweitens hinterlassen die Zellen Spuren, die nach dem Ablösen der Zellen auf den Oberflächen zurückbleiben. Mittels Kombination von TIRAF- und TIRF-Mikroskopie werden die Zelladhäsionsfläche und die Aktinstruktur gleichzeitig beobachtet. Die Verknüpfung beider Methoden stellt eine neue Möglichkeit dar, intrazelluläre Prozesse mit der Zellablösung von thermo-responsiven Oberflächen zu korrelieren. / Modern methods for single-cell analysis are becoming increasingly sensitive. At the same time, requirements for the sample material are on the rise. Today, sample preparation of adherent cells usually includes steps of enzymatic treatment to digest surface proteins thus, inducing cell detachment from culture substrates. This strongly limits the application of different techniques like patch clamp or labelling of extracellular domains of membrane proteins for flow cytometry. Therefore, a new cell detachment method is urgently required. In the present work, new PEG-based thermo-responsive polymers are used for cell culture for the first time. Here, non-destructive detachment of different cell lines from polymer-coated surfaces is realised by controlled temperature reduction. The surface functionality is systematically optimised by varying the concentration of the coating solutions, by artificial surface coating of a cell adhesion-mediating protein (fibronectin) and by co-adsorption of a cell adhesion-mediating peptide (RGD). For detailed analysis of the cell detachment process, TIRF microscopy is used to directly visualise the cell contacts on the thermo-responsive surfaces. Using this technique allows both the quantification and analysis of the reduction of the cell adhesion area during sample cooling. Furthermore, for several cell lines, different behaviours in cell detachment are observed. Cells that have close contact to their substrate like MCF-7 breast cancer cell line and CHO-K1 ovary cells increase the distance between cell membrane and surface, but there is only little decrease of cell-substrate adhesion area. In contrast, L929 fibroblasts reduce the cell adhesion area drastically. Furthermore, the hypothesis that the cell detachment is an active process is shown by lowering the cell metabolism by temperature reduction to 4 °C and by the cell traces that are left behind after rinsing the surfaces. A combination of TIRAF and TIRF enables visualising the cell adhesion area and actin structures. Measuring both parameters simultaneously opens up new possibilities to correlate intracellular and cell detachment processes on thermo-responsive surfaces.

Type 1 diabetes affects one in every 400-600 children and adolescents in the US. Standard therapy with exogenous insulin is burdensome, associated with a significant risk of dangerous hypoglycemia, and only partially efficacious in preventing the long term complications of diabetes. Pancreatic islet transplantation has emerged as a promising therapy for type 1 diabetes. However, this cell-based therapy is significantly limited by inadequate islet supply (more than one donor pancreas is needed per recipient), instant blood-mediated inflammatory reaction, and loss of islet viability/function during isolation and following implantation. In particular, inadequate revascularization of transplanted islets results in reduced islet viability, function, and engraftment. Delivery of pro-vascularization factors has been shown to improve vascularization and islet function, but these strategies are hindered by insufficient and/or complex release pharmacokinetics and inadequate delivery matrices as well as technical and safety considerations. We hypothesized that controlled presentation of angiogenic cues within a bioartificial matrix could enhance the vascularization, viability, and function of transplanted islets. The primary objective of this dissertation was to enhance allogenic islet engraftment, survival and function by utilizing synthetic hydrogels as engineered delivery matrices. Polyethylene glycol (PEG)-maleimide hydrogels presenting cell adhesive motifs and vascular endothelial growth factor (VEGF) were designed to support islet activities and promote vascularization in vivo. We analyzed the material properties and cyto-compatibility of these engineered materials, islet engraftment in a transplantation model, and glycemic control in diabetic subjects. The rationale for this project is to establish novel biomaterial strategies for islet delivery that support islet viability and function via the induction of local vascularization.

The minimization of blood loss represents a significant clinical need in the arena of surgery, trauma, and emergency response medicine. Fibrinogen is our body's native polymer system activated in response to tissue and vasculature injury, and forms the foundation of the most widely employed surgical sealant and hemostatic agent. Non-covalent knob:hole interactions are central to the assembly of fibrin that leads to network and clot formation. This project exploits these affinity interactions as a strategy to direct fibrin polymerization dynamics and network structure so as to develop a temperature-triggered polymerizing fibrin mixture for surgical applications. Short peptides modeled after fibrin knob sequences have been shown to alter fibrin matrix structure by competing with native fibrin knobs for binding to the available holes on fibrinogen and fibrin. The fusion of such knob peptides to a non-native component should facilitate binding of the fused component to fibrinogen/fibrin, and may permit the concomitant modification of the fibrin matrix. We examined this hypothesis in a three-step approach involving (a) analyzing the ability of tetrapeptide knob sequences to confer fibrin(ogen) affinity on a non-fibrin protein, (b) investigating the effect of knob display architecture on fibrin(ogen) structure, and (c) designing a temperature-responsive knob-displaying construct to modulate fibrin(ogen) affinity at different temperature regimes, thus altering fibrin(ogen) structure.

The synthesis of four homologous anthraquinones (AQ I-IV) bearing increasing lengths of polyethylene glycol (PEG) side chains and their binding to AT- and GC-rich DNA hairpins are reported. The molecules were designed such that the cationic charge is at a constant position and the ethylene glycol units chosen to allow significant increases in size with minimal changes in hydrophobicity. The mode and affinity of binding were assessed using circular dichroism (CD), nuclear magnetic resonance (NMR), surface plasmon resonance (SPR), and isothermal titration calorimetry (ITC). The binding affinity decreased as the AQ chain length increased along the series with both AT- and GC-rich DNA. ITC measurements showed that the thermodynamic parameters of AQ I-IV binding to DNA exhibited significant enthalpy-entropy compensation. The enthalpy became more favorable while the entropy became less favorable. The correlation between enthalpy and entropy may involve not only the side chains, but also changes in the binding of water and associated counterions and hydrogen bonding. The interactions of AQ I-IV with GC-rich DNA have been studied via molecular dynamics (MD) simulations. The geometry, conformation, interactions, and hydration of the complexes were examined. As the side chain lengthened, binding to DNA reduced the conformational space, resulting in an increase in unfavorable entropy. Increased localization of the PEG side chain in the DNA groove, indicating some interaction of the side chain with DNA, also contributed unfavorably to the entropy. The changes in free energy of binding due to entropic considerations (-3.9 to -6.3 kcal/mol) of AQ I-IV were significant. The kinetics of a homologous series of anthraquinone threading intercalators, AQT I-IV with calf thymus DNA was studied using the stopped-flow. The threading mechanisms of the anthraquinones binding to DNA showed sensitivity to their side chain length. Fitting of the kinetic data led to our proposal of a two step mechanism for binding of AQT I, bearing the shortest side chain, and a three step mechanism for binding of the three longer homologs. Binding involves formation of an externally bound anthraquinone-DNA complex, followed by intercalation of the anthraquinone for AQT I-IV, then isomerization to another complex with similar thermodynamic stability for AQT II-IV.