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The present studies were aimed at formulating AZD2811-loaded polylactic acid-polyethylene glycol (PLA-PEG) nanoparticles with adjustable release rates without altering the chemical structures of the polymer or active pharmaceutical ingredient (API). This was accomplished through the use of a hydrophobic ion pairing approach. A series of AZD2811-containing nanoparticles with a variety of hydrophobic counterions including oleic acid, 1-hydroxy-2-naphthoic acid, cholic acid, deoxycholic acid, dioctylsulfosuccinic acid, and pamoic acid is described. The hydrophobicity of AZD2811 was increased through formation of ion pairs with these hydrophobic counterions, producing nanoparticles with exceptionally high drug loading-up to five fold higher encapsulation efficiency and drug loading compared to nanoparticles made without hydrophobic ion pairs. Furthermore, the rate at which the drug was released from the nanoparticles could be controlled by employing counterions with various hydrophobicities and structures, resulting in release half-lives ranging from about 2 to 120h using the same polymer, nanoparticle size, and nanoemulsion process. Process recipe variables affecting drug load and release rate were identified, including pH and molarity of quench buffer. Ion pair formation between AZD2811 and pamoic acid as a model counterion was investigated using solubility enhancement as well as nuclear magnetic resonance spectroscopy to demonstrate solution-state interactions. Further evidence for an ion pairing mechanism of controlled release was provided through the measurement of API and counterion release profiles using high-performance liquid chromatography, which had stoichiometric relationships. Finally, Raman spectra of an AZD2811-pamoate salt compared well with those of the formulated nanoparticles, while single components (AZD2811, pamoic acid) alone did not. A library of AZD2811 batches was created for analytical and preclinical characterization. Dramatically improved preclinical efficacy and tolerability data were generated for the pamoic acid lead formulation, which has been selected for evaluation in a Phase 1 clinical trial (ClinicalTrials.gov Identifier NCT 02579226). This work clearly demonstrates the importance of assessing a wide range of drug release rates during formulation screening as a critical step for new drug product development, and how utilizing hydrophobic ion pairing enabled this promising nanoparticle formulation to proceed into clinical development.

Gedatolisib, a PI3K/mTOR dual inhibitor delivered intravenously, is in early clinical trials in women with metastatic ER+ breast cancer. We reasoned that the therapeutic index could be further maximized by encapsulation of gedatolisib in nanoparticles (NP), thereby providing longer half-life, sustained release, blunting of Cmax and associated toxicity, asymmetric distribution to leaky tumor vasculature and the possibility of less frequent dosing. PF-07034663 is a polymeric NP encapsulating gedatolisib, targeted to prostate-specific membrane antigen (PSMA), a clinically validated tumor antigen expressed on prostate cancer cells and the neovasculature of some nonprostate solid tumors. Studies in mice, rats, and cynomolgus monkeys demonstrated that the terminal half-life of PF-07034663 following intravenous administration increased by ~1.5 fold and the Cmax of released gedatolisib from PF-07034663 decreased by ~75 fold compared to gedatolisib delivered by the same route. Gedatolisib released from PF-07034663 exhibited markedly enhanced intratumoral accumulation compared to gedatolisib (~40 fold), indicating enhanced tissue delivery and/or prolonged retention. In exploratory toxicology studies, PF-07034663 caused no hyper-insulinemic spike in rats, in contrast to gedatolisib. To evaluate the antitumor activity of PF-07034663, we performed tumor growth inhibition (TGI) studies in PSMA-positive C4-2 prostate and in PSMA-negative MDAMB361 ER+ breast and A549 lung xenograft tumor models. In the C4-2 model, PF-07034663 showed dose-dependent antitumor efficacy as a single agent, and, in combination with enzalutamide, exhibited enhanced activity leading to tumor regressions. PF 07034663 also exhibited prolonged, dose-dependent inhibition of phosphorylation of S6 (pS6) in the C4-2 model compared to gedatolisib. Interestingly, increased pharmacodynamics (PD) responses compared to gedatolisib were not restricted to PSMA-positive tumors. Moreover, TGI responses were increased in the PSMA-negative A549 lung cancer model, relative to those observed with gedatolisib. PF 07034663 treatment in spontaneous prostate tumors in PTENnullp53mut GEM mice and in subcutaneous allografts of these spontaneous tumors in wild-type mice showed that treatment of PF-07034663 caused similar pS6 inhibition in both models, suggesting that PD modulation is independent of tumor origin or milieu and is less likely due to altered enhanced permeability and retention (EPR) effect. Taken together, PF-07034663 exhibits potential for improved tolerability, sustained tumor PK, prolonged PD modulation, and less frequent dosing schedule compared to gedatolisib. These results support further exploration of gedatolisib in tumor-targeted or non-tumor-targeted nanoparticles in clinical trials as a promising vehicle for delivery of PI3K/mTOR inhibitors to advanced cancer patients. Citation Format: Lianglin Zhang, Gabriel Troche, Ravi Visswanathan, Wenhu Huang, Young-Ho Song, Mary E. Spilker, Zhenxiong Wang, Hui Wang, Anand Giddabasappa, Louise Cadzow, Susan Low, Greg Troiano, Jennifer Lafontaine, Valeria Fantin, Robert T. Abraham, Shubha Bagrodia. Development of a nanoparticle containing the PI3K/mTOR dual Inhibitor, gedatolisib, for cancer therapy [abstract]. In: Proceedings of the AACR Special Conference on Targeting PI3K/mTOR Signaling; 2018 Nov 30-Dec 8; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Res 2020;18(10_Suppl):Abstract nr B25.

A molecular Solomon link was synthesized in high yield through the template-free, coordination-driven self-assembly of a carbazole-functionalized donor and a tetracene-based dinuclear ruthenium(II) acceptor. The doubly interlocked topology was realized by a strategically chosen ligand which was capable of participating in multiple CH⋅⋅⋅π and π-π interactions, as evidenced from single-crystal X-ray analysis and computational studies. This method is the first example of a two-component self-assembly of a molecular Solomon link using a directional bonding approach. The donor alone was not responsible for the construction of the Solomon link, and was confirmed by its noncatenane self-assemblies obtained with other similar ruthenium(II) acceptors.

On account of their nano-scale size, large aspect ratio and high conductivity, conducting polymer have emerged as an attractive choice for conducting composite materials. As part of drive towards finding applications, an examination of the charge transfer (CT) between the conducting polymers and metal species is needed. Morrow et al. have reported on the metal properties of cyclen-based ligand containing Npropionamide donor groups since acetamide oxygen donor is much stronger donor than the alcoholic oxygen. Amide donor is also of tremendous interest because peptide oxygen donors bind K in K-ion channels. However, there is no work related with chemosensor properties by metal or electronic interactions for amide-fluorophore-introduced conducting polymer. Among the conducting polymer, polyaniline (PANI) is a unique conjugated polymer in that it can be tailored for specific applications through acid/base doping process. PANI nanostructures are of great current interest since they have a reactive-NH group in the polymer chain flanked on either side by phenylene rings. We have recently shown that PANIs can provide a very high chemical flexibility for the complexation of metal ions. Mechanisms of chemical interactions between PANI and transition metals are also intensively discussed by T. Hirao et al. and relate to the importance of metal ion sensing in biology, medicine, and the environment. Most colorimetric or luminescent chemosensors for transition metal ions are designed by employing intramolecular charge transfer (ICT) or photoinduced electron transfer (PET) mechanism. One significant advantages of nanoporous polyaniline conducting particles is that appropriate design combined with reactive binding sites in EB or LB could allow efficient control of colorimetric and conducting changes by metal complexation. In order to demonstrate the above proposal, two structurally similar EB (two imine and two NH groups for four aromatic rings) and LB (four NH groups for four aromatic rings) type PANIs were designed on the basis of the terms of coordination via the nitrogen lone pairs. Meanwhile, fluorescent pyrene (Py)-fuctionalized copolymers has been evaluated as a sensor for embedded between PANI leucoemeraldine base (LB) and Py, which could display colorimetric change in the presence of the metal nitroaromatic explosive materials (NAC) to give fluorescence quenching by π-π-stacked complexes. In addition, the interest in these materials has been driven by the ability of the conjugated polymers to create large signal amplification relative to small molecule chemosensors due to the delocalization and rapid diffusion of excitons throughout the individual polymer chains, so-called molecular wire effect or one point contact and multipoint response effect, in solution. This encouraged us to develop multi-chemosensor based on amide bond ions as well as fluorescent quenching by electron poor NAC species.

Novel arene-ruthenium [2+2] metalla-rectangles, 4 and 5, were synthesized by the self-assembly approach using a dipyridyl amide ligand (3) and arene-ruthenium acceptors (arene: benzoquinone (1); naphthacenedione (2)), and characterized by NMR and ESI-MS. The solid-state structure of 5 determined by X-ray diffraction shows the encapsulated diethyl ether molecules in the rectangular cavity of 5. The luminescent 5 was further utilized for anion sensing where the amidic linkage serves as a hydrogen bond donor site for anions, and the ruthenium moiety serves as a signaling unit. A UV-vis titration study demonstrates that, while 5 interacts very weakly with the common mono anions as well as flexible dicarboxylate anions such as malonate and succinate, it displays significant binding affinity (K > 103 in MeOH) for the rigid multi-carboxylate anions such as oxalate, citrate, and tartrate in a 1:1 fashion. It is suggested that the 1:1 bidentate hydrogen bonding assisted by the proper geometrical complementarities is mainly responsible for the increased affinity of 5 towards such anions. In particular, a fluorescence titration study reveals a large fluorescence enhancement of 5 upon binding with multi-carboxylate anions. This indicates that the fluorescence enhancement is attributed to the blocking of the photo-induced electron transfer process from the arene-Ru moiety to the amidic donor in 5 as a result of hydrogen bonding between the donor and the anion.

We described reversible calorimetric changes using nanoporous polyaniline (half-reduced form: emeraldine base (EB), and fully reduced form: leucoemeraldine base (LB)) particles and transition metal ions (Ag + , Cu 2+ , or Cr 3+ ) based on metal complexation. We analyzed the metal complexation capabilities of the polyaniline by UV and IR spectral changes to be used as sensing metal ions. It was demonstrated that the nature of the resulting solutions formed from the different interaction of the EB or LB system of nanoporous particles is strongly dependent on the nature of the cation metal species such as the EB or LB/metal molar ratio.

Mapping the drug distribution in a polymeric film and following the subsequent changes that result during and after drug release is important to better understand the mechanism of drug release. This under- standing leads to more efficiently designed tailor-made release profiles for drug-containing biomedical devices. Coherent anti-Stokes Raman scattering (CARS) micros- copy was used for in situ imaging of local drug distribu- tion in polymeric films, taking advantage of the three- dimensional (3D) resolution, high speed, high sensitivity, and noninvasiveness of the technology. Additionally, the morphological changes of poly(styrene-b-isobutylene-b- styrene) (SIBS) films during paclitaxel release were char- acterized by scanning electron microscopy, and drug release was quantitatively determined by high perform- ance liquid chromatography. The time-dependent changes in the 3D distribution of paclitaxel in the polymer film were visualized using CARS microscopy. CARS images showed that the paclitaxel was uniformly distributed throughout the SIBS matrix. Changes in the paclitaxel dis- tribution during release were monitored using depth in- tensity profiles and showed that, upon exposure of the paclitaxel-loaded film to a release medium, the quantita- tive CARS intensity of paclitaxel decreased. These results indicate that paclitaxel was dissolved and depleted from the SIBS film during in vitro drug elution, supporting the use of CARS microscopy as an effective nondestructive technique for chemical imaging of paclitaxel elution dy- namics in polymer films. 2008 Wiley Periodicals, Inc. J Biomed Mater Res 87A: 913-920, 2008

Inhye Kim,1,* Young Ho Song,2,* Nem Singh,2 Yong Joon Jeong,3 Jung Eun Kwon,3 Hyunuk Kim,4 Young Mi Cho,3 Se Chan Kang,3 Ki-Whan Chi2 1Laboratory of Bio-Resources, Yongin-si, Gyeonggi-Do, 2Department of Chemistry, University of Ulsan, Ulsan, 3Department of Life Science, Gachon University, Seongnam, 4Energy Materials Lab, Korea Institute of Energy Research, Daejeon, Republic of Korea *These authors contributed equally tothis work Abstract: Nano-sized multinuclear ruthenium complexes have rapidly emerged as promising therapeutic candidates with unique anticancer activities. Here, we describe the coordination-driven self-assembly and anticancer activities of a set of three organometallic tetranuclear Ru(II) molecular bowls. [2+2] Coordination-driven self-assembly of 3,6-bis(pyridin-3-ylethynyl)phenanthrene (bpep) (1) and one of the three dinuclear arene ruthenium clips, [(ƞ6-p-iPrC6H4Me)2Ru2-(OOOO)][OTf]2 (OOOO=2,5-dioxido-1,4-benzoquinonato, OTf = triflate) (2), 5,8-dioxido-1,4-naphthoquinonato (3), or 6,11-dioxido-5,12-naphthacenediona (4), resulted in three molecular bowls 5–7 of general formula [{(ƞ6-p-iPrC6H4Me)2Ru2-(OOOO)}2(bpep)2][OTf]4. All molecular bowls were obtained as triflate salts in very good yields (>90%) and were fully characterized using multinuclear nuclear magnetic resonance (NMR), electrospray ionization–mass spectrometry (ESI-MS), and elemental analysis. The structure of the representative molecular bowl 5 was confirmed by single-crystal X-ray diffraction analysis. The anticancer activities of molecular bowls 5–7 were determined by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide, autophagy, and Western blot analysis. Bowl 6 showed the strongest cytotoxicity in AGS human gastric carcinoma cells and was more cytotoxic than doxorubicin. In addition, autophagic activity and the ratio of apoptotic cell death increased in AGS cells by treatment with bowl 6. Bowl 6 also induced autophagosome formation via upregulation of p62 and promotion of the conversion of LC3-I to LC3-II. Moreover, bowl 6 promoted apoptotic cell death through downregulation of Akt/mTOR activation, followed by increased caspase-3 activity. These results suggest that bowl 6 induces gastric cancer cell death via modulation of autophagy and apoptosis. Bowl 6 is a potent anticancer agent and a potential treatment for human gastric cancer that merits further study. Keywords: phenanthrene, ruthenium, coordination self-assembly, gastric cancer, Akt/mTOR

Anionic and cationic phospholipid liposomes have been prepared from dipalmitoylphosphatidylcholine (DPPC) — phosphatidylinositol (PI) and DPPC-cholesterol-stearylamine (SA) mixtures over a range of composition and targeted to biofilms of the skin-associated bacterium Staphylococcus epidermidis to establish the optimum PI and SA content for targeting. The interaction of liposomes of optimum composition with the bacteria were visualized by electron microscopy using negative staining with uranyl acetate and phosphotungstic acid. It has been demonstrated that the liposomes absorb extensively to the bacterial surface. Immunoliposomes have been prepared with a covalently linked monoclonal antibody raised to antigenic determinants on the surface of the oral bacterium Streptococcus oralis. The targeting of the immunoliposomes to this bacterium has been visualized using a second gold labelled anti-antibody. As for the anionic and cationic liposomes the immunoliposomes adsorb to the surface of the bacteria. The results add support to the concept of using liposomes for the delivery of bactericides or therapeutic agents to bacteria.

Phospholipid (dipalmitoylphosphatidylcholine (DPPC) plus phosphatidylinositol (PI)) proteoliposomes with surface bound lectins (succinylated concanavalin A (s con A) and wheat germ agglutinin (WGA)) have been prepared covering a range of size and surface density of lectin. Negatively charged phospholipid liposomes from DPPC-PI mixtures covering a range of PI mole % and positively charged liposomes from DPPC-cholesterol-stearylamine (SA) mixtures covering a range of SA mole % have been prepared. The targeting of the liposomes and proteoliposomes to a range of oral and skin-associated been prepared. The targeting of the liposomes and proteoliposomes to a range of oral and skin-associated bacterial biofilms has been investigated. The oral bacteria Streptococcus mutans and gordonii and the skin-associated bacterium Coryneform hofmanni can be targeted with s con A bearing proteoliposomes while the skin associated bacterium Staphylococcus epidermidis can be targeted with WGA bearing proteoliposomes. Both oral and skin-associated bacteria can be targeted with positively charged liposomes although the extents of adsorption to the biofilm are low except for Staphylococcus epidermidis. In the case of negatively charged liposomes targeting is critically dependent on the PI content of the liposomes and for all the bacteria studied optimum levels PI for targeting have been found. The adsorption of the oral bacterium Streptococcus gordonii to immobilised monolayers having the optimum PI level for adsorption has been studied by total internal reflection microscopy (TIRM). Both the phospholipid and proteoliposomes have been used to deliver the bactericide Triclosan to biofilms. All the systems studied inhibited bacterial growth to varying degrees.(ABSTRACT TRUNCATED AT 250 WORDS)

The synthesis of new 2+2 metalla-rectangles via coordination driven self-assembly of octahedral Ru(II) based acceptors and amide donors is described. To evaluate their in vitro cytotoxic properties, preliminary biological assays were carried out for various human cancer cell lines, and our results show that the cytotoxicity level of 3 is comparable or even greater in the cases of SK-hep-1 and HCT-15 than that of the reference drug cisplatin.

Background: BIND-2206 Accurins are novel polymeric nanoparticles encapsulating MK-2206, a Merck AKT inhibitor in phase 2 trials. MK-2206 targets the phosphatidylinositol 3-kinase (PI3K) pathway via AKT inhibition and has demonstrated therapeutic efficacy in the treatment of cancer albeit with dose limiting toxicities. Accurins have shown promise for targeting oncology agents preferentially to tumors, while limiting systemic exposure. To determine if encapsulation of MK-2206 improves therapeutic index, studies were performed to evaluate pharmacokinetics (PK), pharmacodynamics (PD), tolerability and anti-tumor activity compared to parent MK-2206. Materials and Methods: PK of four Accurin formulations with varying in vitro drug release rates was evaluated. Based on these data, two lead Accurins (BIND-2206C and BIND-2206D) were selected for further characterization. Since AKT inhibitors are documented to induce hyperglycemia in mice, blood glucose levels were also evaluated after acute administration of BIND-2206 Accurins or parent MK-2206 as a measure of tolerability. Using a panel of human tumor xenografts (VCaP, SK-OV-3 and BT-474) anti-tumor activity of the Accurins was assessed in mice. When tumors were established mice were dosed orally with parent MK-2206 or intravenously with BIND-2206 Accurins two or three times per week on a three week cycle. Tumor volume was measured post treatment to determine anti-tumor activity. Following final drug administration, tumors were collected for PK and PD evaluation. Extent and duration of tumor target inhibition was evaluated by measuring pAKT and total AKT using a mesoscale discovery method and was correlated to tumor MK-2206 levels. Results: Accurins BIND-2206C and BIND-2206D significantly enhanced the PK profile of parent MK-2206 by increasing Cmax (33 fold) and AUC (222 fold) and decreasing clearance (38 fold) in mice. In addition, both BIND-2206 Accurins improved tolerability as demonstrated by no hyperglycemic response compared to a 300% increase in blood glucose in nude mice treated with parent MK-2206. In the VCaP human prostate cancer tumor model, BIND-2206C inhibited tumor growth by 88% and BIND-2206D induced 16% tumor regression showing significant enhancement of anti-tumor efficacy compared to 55% tumor growth inhibition achieved by parent MK-2206. This correlated with high tumor exposure at 72 hours and prolonged tumor PD at 96 hours post dose for both Accurins compared to parent MK-2206. A similar increase in tumor exposure and prolonged PD response resulted in enhanced anti-tumor efficacy for BIND-2206 Accurins in the SK-OV-3 human ovarian cancer tumor model. In the BT-474 HER2 over-expressing human breast cancer tumor model, BIND-2206 Accurins did not improve efficacy compared to parent drug, although there was significant and prolonged tumor PD correlating with enhanced tumor PK. This suggests that anti-tumor efficacy is model specific and a combination strategy in the BT-474 model may be advantageous. Conclusions: BIND-2206 Accurins showed differentiated PK, increased tumor exposure, prolonged duration of target inhibition, superior efficacy and enhanced tolerability compared to parent MK-2206. These data suggest that nanoparticle formulations of the AKT inhibitor, MK-2206, may provide improved tolerability and therapeutic efficacy in a clinical setting. Citation Format: Louise Cadzow, Michael H. Lam, Young Ho Song, Maria Figueiredo, Hong Wang, David De Witt, Vincenzo Pucci, Jan-Rung Mo, Eric Lewis-Clark, Heidi Ferguson, Marian Gindy, Susan Low, Steve Zale, Jeff Hrkach, Caroline McGregor, Brian J. Long. Accurins improve the pharmacokinetics, pharmacodynamics, tolerability and anti-tumor activity of the AKT inhibitor MK-2206. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr C197.

We investigate the properties of InGaN-based vertical-type solar cells having wavelengths ranging from the ultraviolet to green regions. It is well known that InGaN-based solar cells require a high indium composition to obtain high conversion efficiency. However, although InGaN-based solar cells with a high indium composition have been fabricated, their conversion efficiency has not sufficiently increased. Therefore, to further understand carrier transport, we measured the bias-dependent external quantum efficiency. For vertical-type green solar cells with a high indium composition, we confirmed that they have a higher short circuit current than other samples tested due to their broader overlapping region with the solar spectrum, though their fill factor remained low due to their high barrier height and strong piezoelectric field, which caused a reduction in the carrier tunneling rate.

Liposomes have been prepared from dipalmitoylphosphatidylcholine (DPPC) incorporating the cationic lipids stearylamine (SA), dimethyldioctadecylammonium bromide (DDAB) and dimethylaminoethane carbamoyl cholesterol (DCchol) and the anionic lipids dipalmitoylphosphatidylglycerol (DPPG) and phosphatidylinositol (PI). Their adsorption to biofilms of skin-associated bacteria (Staphylococcus epidermidis and Proteus vulgaris) and oral bacteria (Streptococcus mutans and sanguis) has been investigated as a function of mole % cationic and anionic lipid. Targeting (adsorption) was most effective for the systems DPPC-chol-SA, DPPC-DPPG and DPPC-PI liposomes to S. epidermidis. The effect of extracellular mucopolysaccharide on targeting was investigated for S. epidermidis biofilms. It was found that targeting increased with the level of extracellular mucopolysaccharide for all liposome compositions studied. The delivery of the oil-soluble bactericide Triclosan and the water soluble bactericide chlorhexidine was studied for a number of liposomal compositions. Superior delivery of both bactericides relative to the free bactericide occurred for DPPC-chol-SA liposomes and for Triclosan delivery by DPPC-DPPG and DPPC-PI liposomes targeted to S. epidermidis at low bactericide concentrations. DPPC-chol-SA liposomes were also effective for delivery of Triclosan to S. sanguis biofilms. Double labelling experiments using [14C]-chlorhexidine and [3H]-DPPC suggested that there was exchange between adsorbed liposomes which had delivered bactericide to the biofilm and those in the bulk solution implying a diffusion mechanism for bactericide delivery.

We demonstrated improved luminous efficacy for GaN-based vertical light emitting diodes (VLEDs) employing a low index layer composed of silicon dioxide (SiO2) on the top surface. Three-dimensional (sic)nite-difference time-domain simulations for the fabricated VLED chip show that the penetration ratio of the emitted/reflected light into the VLED chip decreased by approximately 20% compared to a normal VLED chip. This result is in good agreement with an empirical study stating that white VLEDs having a SiO2 layer exhibit an 8.1% higher luminous efficacy than white VLEDs with no layer at an injection current of 350 mA. Photons penetrating into the VLED chip, which become extinct in the VLED chip, are reflected from the SiO2 layer due to the index contrast between the SiO2 layer and epoxy resin containing phosphor, with no degradation of the light-extraction efficiency of the VLED chip. As such, this structure can contribute to the enhancement of the luminous efficacy of VLEDs. (c) 2013 Optical Society of America

Phospholipid liposomes have been prepared from phospholipid mixtures including dipalmitoylphosphatidylcholine/phosphatidylinositol (DPPC/PI) and DPPC/dipalmitoylphosphatidylglycerol (DPPC/DPPG) mixtures and targeted to adsorbed biofilms of the skin-associated bacteria Staphylococcus epidermidis and Proteus vulgaris and the oral bacterium Streptococcus sanguis. The effects of time, liposome concentration and density of bacteria in the biofilm have been studied in detail for Staphylococcus epidermidis. The targeting (as assessed by the apparent monolayer coverage of the biofilms by liposomes) to the biofilms was found to be sensitive to the mol% of PI and DPPG in the liposomes and optimum levels of PI were found for targeting to each bacterium. The use of PI and DPPG-containing liposomes for the delivery of the bactericide, Triclosan, to biofilms of Staphylococcus epidermidis was studied as a function of the amount of Triclosan carried by the liposomes. All the liposome systems tested inhibited the growth of bacteria from the biofilms after brief (2 min) exposure to Triclosan-carrying liposomes. At low Triclosan levels bacterial growth inhibition by Triclosan-carrying liposomes exceeded that by an equivalent level of free Triclosan. After short periods (min) of exposure of biofilms to Triclosan-carrying liposomes the bactericide was shown to preferentially concentrate in the biofilms relative to its liposomal lipid carrier. The results suggest that phospholipid liposomes with appropriately chosen lipid composition have potential for the targeting and delivery of bactericide to bacteria.

Reversible photochromic changes and photoimaging were accomplished by H+ transfer between spiropyran and fluorescein in a polymer matrix.

Streptococcus sanguis strain C104 Proteovesicles (proteoliposomes) have been used for the delivery of bactericides t o several strains of oral and skinassociated bacteria adsorbed on solid surfaces (microtitre plates) I1.21. The preparation and characterisation of proteoliposomes is relatively complex 131 and simpler methods of liposomal targeting and delivery are desirable. One possible approach is t o exploit the negative charge on the surface of bacteria 141 by targeting w i th positively charged liposomes. Here positively charged liposomes were prepared by the extrusion method 151 in phosphate buffered saline (pH 7.4) from dipalmitoylphosphatidylcholine (DPPCI-cholesterol mixtures (weight ratio 1 :0.26) containing variable amounts of stearylamine (SA) in a range up t o 17 w t % of the total liposomal lipid. The liposomes, which had weight-average diameters in the range 100-140nm. were radiolabelled w i th 3H-DPPC. Two methods were used t o study the interaction of the liposomes w i th bacteria; liposome adsorption t o adsorbed biofilms on microtitre plates and adsorption t o bacterial suspensions using a solution-depletion technique. In the former method adsorbed biofilms were prepared by incubation of bacterial suspensions of specific optical absorbance (0.5) in microtitre plate wells for 18 hours. Liposome suspensions were incubated w i th the biofilms for 2 hours at 37°C. after which the liquid phase was removed and the biofilm was dispersed in 1 % w/v sodium ndodecylsulphate and analysed by scintillation counting to determine the extent of liposome adsorption. Liposome adsorption was expressed as the percentage apparent monolayer coverage (% amc) of the biofilm calculated from the projected diameter of the liposomes and the area of the biofilm. In the solution-depletion method the liposomes were incubated w i th bacterial suspensions of known cell concentration (as determined by cell counting) for 2 hours; the suspension was gently centrifuged t o pellet the bacteria (5609 for 10 minutes) and the supernatant analysed for liposomal lipid. From the bacterial cell number and depletion of liposome concentration in the supernatant, the number of liposomes adsorbed per bacterium was determined as a function of liposomal lipid concentration.