Photodynamic inactivation of microorganisms has gained substantial attention due to its unique mode of action, in which pathogens are unable to generate resistance, and due to the fact that it can be applied in a minimally invasive manner. In photodynamic therapy (PDT), a non-toxic photosensitizer (PS) is activated by a specific wavelength of light and generates highly cytotoxic reactive oxygen species (ROS) such as superoxide (O2−, type-I mechanism) or singlet oxygen (1O2*, type-II mechanism). Although it offers many advantages over conventional treatment methods, ROS-mediated microbial killing is often faced with the issues of accessibility, poor selectivity and off-target damage. Thus, several strategies have been employed to develop target-specific antimicrobial PDT (aPDT). This includes conjugation of known PS building-blocks to either non-specific cationic moieties or target-specific antibiotics and antimicrobial peptides, or combining them with targeting nanomaterials. In this review, we summarise these general strategies and related challenges, and highlight recent developments in targeted aPDT.

A BODIPY-based fluorescent probe integrated with an aldoxime unit shows a remarkable fluorescence "turn-on" response to hypochlorous acid (HOCl). The oxidative dehydrogenation of BODIPY aldoxime by HOCl results in a distinct fluorescence enhancement as well as a change in color from red to orange.Izmir Institute of Technology (IZTECH

Pd(0)-catalyzed carbonylation of (Z)-2-en-4-yn carbonates in the presence of a balloon pressure of CO in an alcohol donates vinylallenyl esters with an exclusively E-configuration and in high yields. The fact that no such reactivity could be observed with E-configured enyne carbonates may indicate that the reaction is promoted via the cooperative coordination of palladium with both alkynyl and carbonate moieties. Supporting Information Available. Detailed experimental procedures, and compound characterization data. This material is available free of charge via the Internet at http://pubs.acs.org.

The methylene blue-polymyxin conjugate demonstrated high selectivity, sensitivity and phototoxicity against Gram-negative bacteria, including in early biofilm models.

We described the design and synthesis of a molecular sensor based on a rhodamine/BODIPY platform that displayed differential fluorescence responses towards Hg 2+ and Au 3+ and demonstrated its utility in intracellular ion imaging.In recent years, the construction of fluorescent molecular sensors for the detection of metal ion species has received a great deal of attention. 1 To date a large number of molecular sensors have been designed and developed, the majority of which are single-ion responsive and present no great challenge to researchers. Compared to single-ion responsive molecular sensors, however, the construction of multi-ion responsive molecular sensors with multiple emission modes are extremely challenging. 2 Molecular sensors displaying differential responses towards multiple ions are indispensable for designing molecular logic gates and molecular keypad lock devices. 3,4The challenge of multiple analyte recognition presents several detection strategies. Incorporating multiple binding motifs onto a single sensing molecule, or alternatively, combining different transducing units (chromophores/fluorophores), allows for rapid access to molecular sensors with multiple emission modes. 2 We envisaged that incorporating both a chemosensor and a chemodosimeter onto a single molecule could provide a suitable sensing platform for the differential detection of metal species. On the basis of this hypothesis, we constructed a molecular sensor possessing two different fluorophore units chemically integrated with each other. Both fluorophore units were elegantly designed to be non-emissive (i.e., ''off'') in their initial states and are expected to turn on respectively in response to the metal species of interest. To the best of our knowledge, molecular sensors based on this novel approach have not been covered in the literature.Ionic species of mercury (Hg 2+ ) and gold (Au 3+) share several similarities in terms of coordination properties. As both metal species show high affinities to thiols, they have the potential to interact with sulfur bearing biomolecules such as enzymes, proteins, and DNA. As a result, these metal species can disturb a series of cellular processes that lead to toxicity in humans. . This fluorescent probe, reported by Dong et al., operates through a single emission mode and the differentiation is highly dependent on the sensing conditions. Obviously, there is a high demand for the development of molecular sensors that can differentiate multiple analytes of a similar chemical nature (e.g. Hg 2+ and Au 3+ ). In addition, smallmolecule fluorescent sensors allowing the intracellular monitoring of multiple ions via differential responses are of high necessity for real-time cell imaging studies. Herein, we present the design, synthesis, spectral properties, and cell imaging studies of RhS-BOD, a new ''turn-on'' multifluorescent probe that allows the Hg 2+ and Au 3+ species to be differentiated on the basis of distinct fluorescence responses. RhS-BOD constitutes a boron-dipyrromethene (BODIPY...

A spermine-like polymer was synthesized via reversible addition-fragmentation chain transfer polymerization as a potential endosomal escaping agent. A new methacrylate monomer, 2-((tertbutoxycarbonyl)(2-((tert-butoxycarbonyl)amino)ethyl)amino)ethylmethacrylate (BocAEAEMA), was prepared and then polymerized via RAFT polymerization at constant monomer or initiator concentration increase in M n with monomer conversion was also observed. P(BocAEAEMA)s with controlled molecular weights and narrow molecular weight distributions were obtained. The in vitro cytotoxicity and proton sponge capacity of deprotected polymers P(AEAEMA) were investigated in comparison with a widely used endosomal-disruptive polymer, PEI. P(AEAEMA)s were found to possess proton sponge capacity comparable with PEI. More importantly, P(AEAEMA)s were not toxic on NIH 3T3 cells at concentrations where PEI (25 kDa) was highly toxic (0.4 mM and above). P(AEAEMA) was able to fully condense a DNA fragment at nitrogen/phosphate (N/P) ratios of 10 and above, as evidenced by gel electrophoresis. P(BocAEAEMA) was then chain-extended with a model sugar monomer, mannose-acrylate (ManAc), to yield P(AEAEMA)-b-P(ManAc) block copolymers, to potentially provide cell-recognition ability to the polyplex particles. Although the presence of the P(ManAc) block partially inhibited the interaction of P(AEAEMA) with DNA, P(AEAEMA) 13 -b-P(ManAc) 7 was able to form polyplexes with DNA at N/P ratios ranging between 20/1 and 2/1. Dynamic light scattering measurements showed that while P(AEAEMA) (M n ¼ 5.5 kDa) and DNA formed polyplex particles having a hydrodynamic diameter (D h ) of 125 AE 51 nm, P(AEAEMA) 13 -b-P(ManAc) 7 and DNA formed particles with a smaller D h of 38 AE 10 nm.

Understanding intermolecular interactions between drugs and proteins is very important in drug delivery studies. Here, we studied different binding interactions between salicylic acid and bovine serum albumin (BSA) using electron paramagnetic resonance (EPR) spectroscopy. Salicylic acid was labeled with a stable radical (spin label) in order to monitor its mobilized (free) or immobilized (bound to BSA) states. In addition to spin labeled salicylic acid (SL-salicylic acid), its derivatives including SL-benzoic acid, SL-phenol, SL-benzene, SL-cyclohexane and SL-hexane were synthesized to reveal the effects of various drug binding interactions. EPR results of these SL-molecules showed that hydrophobic interaction is the main driving force. Whereas each of the two functional groups (-COOH and -OH) on the benzene ring has a minute but detectable effect on the drug-protein complex formation. In order to investigate the effect of electrostatic interaction on drug binding, cationic BSA (cBSA) was synthesized, altering the negative net charge of BSA to positive. The salicylic acid loading capacity of cBSA is significantly higher compared to that of BSA, indicating the importance of electrostatic interaction in drug binding. Moreover, the competitive binding properties of salicylic acid, ibuprofen and aspirin to BSA were studied. The combined EPR results of SL-salicylic acid/ibuprofen and SL-ibuprofen/salicylic acid showed that ibuprofen is able to replace up to ∼83% of bound SL-salicylic acid, and salicylic acid can replace only ∼14% of the bound SL-ibuprofen. This indicates that ∼97% of all salicylic acid and ibuprofen binding sites are shared. On the other hand, aspirin replaces only ∼23% of bound SL-salicylic acid, and salicylic acid replaces ∼50% of bound SL-aspirin, indicating that ∼73% of all salicylic acid and aspirin binding sites are shared. These results show that EPR spectroscopy in combination with the spin labeling technique is a very powerful method to investigate drug binding dynamics in detail.

An ESIPT-based fluorescent dye, 3-hydroxyflavone, is chemically masked with an electrophilic cyanate motif in order to construct a fluorescent probe for cellular sulfur species. This novel probe structure, displays an extremely fast, highly sensitive and selective "turn-on" type fluorescent response toward H 2 S. We have also documented its utility for imaging of H 2 S in the living cells. H ydrogen sulfide (H 2 S), the smallest member among cellular sulfur species, plays critical roles in the functioning of living organisms. The compound is produced in biological systems from various sulfur-containing biomolecules and through a range of particular enzymatic pathways. The assessment of H 2 S levels in the cellular milieu is clearly vital to investigations of cell function and the early diagnosis of some diseases. Understanding the diverse contributions of H 2 S to physiology and pathology therefore first requires the development of efficient methods of visualizing H 2 S production and distribution in living systems. In related research, sustained attention has been paid to the development of molecular tools for probing cellular sulfur species.23−30 Among known analytical tools; fluorescence-based assays are particularly attractive, for they allow the real-time visualization of target species in cellular milieus. During the last several decades, numerous types of fluorescent H 2 S probes have appeared in scientific literature on the topic, most of them involving the use of specific chemical reactions to exploit the reactive and reductive nature of H 2 S. 31−41In general, the construction of any reaction-based H 2 S probe relies on modifying a fluorescent reporter with a reactive masking moiety, which splits away by interacting with H 2 S. To attain high selectivity over other relevant sulfur species, these masking moieties are necessarily highly specific to H 2 S ( Figure 1). 42−48 There are several important issues that have to be taken into account when designing a H 2 S recognition system. At the heart of the matter lies the discrimination of H 2 S over other biological sulfur species such as cysteine and glutathione. Low sensitivity and prolonged response times are other significant stumbling blocks that require attention. Moreover, most masking groups used in probe structures are relatively large