There is increasing interest in constructing artificial cells by functionalising lipid vesicles with biological and synthetic machinery. Due to their reduced complexity and lack of evolved biochemical pathways, the capabilities of artificial cells are limited in comparison to their biological counterparts. We show that encapsulating living cells in vesicles provides a means for artificial cells to leverage cellular biochemistry, with the encapsulated cells serving organelle-like functions as living modules inside a larger synthetic cell assembly. Using microfluidic technologies to construct such hybrid cellular bionic systems, we demonstrate that the vesicle host and the encapsulated cell operate in concert. The external architecture of the vesicle shields the cell from toxic surroundings, while the cell acts as a bioreactor module that processes encapsulated feedstock which is further processed by a synthetic enzymatic metabolism co-encapsulated in the vesicle.

As potential targets for polyphosphoinositides, activation of protein kinase C (PKC) isotypes (␤ 1 , ⑀, , ) and a member of the PKC-related kinase (PRK) family, PRK1, has been compared in vitro. PRK1 is shown to be activated by both phosphatidylinositol 4,5-bisphosphate (PtdIns 4,5-P 2 ) as well as phosphatidylinositol 3,4,5-trisphosphate (PtdIns-3,4,5-P 3 ) either as pure sonicated lipids or in detergent mixed micelles. When presented as sonicated lipids, PtdIns-4,5-P 2 and PtdIns-3,4,5-P 3 were equipotent in activating PRK1, and, furthermore, sonicated phosphatidylinositol (PtdIns) and phosphatidylserine (PtdSer) were equally effective. In detergent mixed micelles, PtdIns-4,5-P 2 and PtdIns-3,4,5-P 3 also showed a similar potency, but PtdIns and PtdSer were 10-fold less effective in this assay. Similarly, PKC-␤ 1 , -⑀, and -were all activated by PtdIns-4,5-P 2 and PtdIns-3,4,5-P 3 in detergent mixed micelles. The activation constants for PtdIns-4,5-P 2 and PtdIns-3,4,5-P 3 were essentially the same for all the kinases tested, implying no specificity in this in vitro analysis. Consistent with this conclusion, the effects of PtdIns-4,5-P 2 and PtdIns-3,4,5-P 3 were found to be inhibited at 10 mM Mg 2؉ and mimicked by high concentrations of inositol hexaphosphate and inositol hexasulfate. The similar responses of these two classes of lipid-activated protein kinase to these phosphoinositides are discussed in light of their potential roles as second messengers.The phosphatidylinositol 3-kinase family of lipid kinases are responsible for the phosphorylation of inositol lipids at the 3-OH position (reviewed in Ref. 1). In response to various agonists, phosphatidylinositol 3,4,5-trisphosphate (PtdIns-3,4,5-P 3 ) 1 accumulates and labeling studies suggest that this is the primary product and as such is the most likely second messenger candidate (2). While this remains an attractive hypothesis, in the absence of a defined intracellular target(s), the operation of the "PtdIns 3-kinase signaling pathway" will remain enigmatic.By their nature, lipid-dependent protein kinases are attractive candidates as targets for the postulated role of PtdIns-3,4,5-P 3 as a second messenger. Protein kinase C (PKC) isotypes constitute the major group of such enzymes, but several recent reports have indicated the existence of an additional class of lipid-activated protein kinases. These kinases, termed PKC-related kinases (PRKs) are closely homologous to PKC isotypes in the catalytic domain while retaining a distinct amino-terminal regulatory domain ((3, 4) see Fig. 6A). Unlike the PKCs which characteristically retain a cysteine-rich C1 domain responsible for effector binding, the PRKs do not encode a C1 domain but show two distinct conserved regulatory domains termed HR1 and HR2 (3). Consistent with the lack of a C1 domain, it has become clear that while the PRKs resemble PKCs in being activated by proteolysis, they differ from PKCs in not being activated by phorbol esters. However, like PKC, various fatty acids and phospholipids have bee...

Iron oxide nanoparticles were made in the presence of three carboxylic acid functionalised organic ligands (tiopronin, oxamic acid and succinic acid) using a co-precipitation method. The iron oxide was a mixture of magnetite and maghemite with an average crystallite size less than 10 nm. The samples were all dialysed prior to analysis to ensure high purity. Without the presence of a carboxylic acid, the dialysis purification stage invoked complete precipitation and the sample was completely intractable. The carboxylic acid stabilised particles could be dissolved in water to form a stable solution. The samples prepared with tiopronin and succinic acid were close to neutral pH and were suitable for magnetic fluid hyperthermia testing on Staphyloccocus aureus. Iron oxide produced with tiopronin was able to achieve a 10 7 -fold reduction in the viable count of the organism using a 2 Â 2 minute exposure to an AC magnetic field and this bactericidal effect could still be achieved using the same batch of particles one week later. Oxidation of the samples did occur with aging or sonication and made the heating response less effective after one month. The tiopronin stabilised nanoparticles were able to achieve substantial kills of bacteria at concentrations between 6.25-50 mg/ml. This is, to our knowledge, the first time magnetic hyperthermia has been used to kill bacteria. The heating rates obtained from using an external magnetic alternating field on the iron oxide nanoparticle solutions were four times greater than the best commercially available material. This novel method of killing bacteria could form the basis of a new approach to the treatment of a variety of infectious diseases.

Covalently coupling toluidine blue O-tiopronin to a gold nanoparticle forms an enhanced, exceptionally potent antimicrobial agent when activated by white light or 632 nm laser light. Aqueous solutions of tiopronin-gold nanoparticles had no antimicrobial effect and, when added to solutions of toluidine blue O, did not enhance the antimicrobial effect of the latter. The minimum bactericidal concentration of the covalently coupled toluidine blue O-tiopronin gold conjugate for Staphylococcus aureus was at least four times lower than that of free toluidine blue O.