The antibacterial mechanism of the Cu-containing materials has not been fully understood although such understanding is crucial for the sustained clinical use of Cu-containing antibacterial materials such as bone implants. The aim of this study is to investigate the molecular mechanisms by which the Gram-positive Staphylococcus aureus is inactivated through Cu-bearing titanium alloys (Ti6Al4V5Cu). Cu ions released from the alloys are found to contribute to lethal damage of bacteria. They destroy the permeability of the bacterial membranes, resulting in the leakage of reducing sugars and proteins from the cells. They also promote the generation of bacteria-killing reactive oxygen species (ROS). The ROS production is confirmed by several assays including fluorescent staining of intracellular oxidative stress, detection of respiratory chain activity, and measurement of the levels of lipid peroxidation, catalase, and glutathione. Furthermore, the released Cu ions show obvious genetic toxicity by interfering the replication of nuc (species-specific) and 16SrRNA genes, but with no effect on the genome integrity. All of these effects lead to the antibacterial effect of Ti6Al4V5Cu. Collectively, our work reconciles the conflicting antibacterial mechanisms of Cu-bearing metallic materials or nanoparticles reported in the literature and highlights the potential use of Ti6Al4V5Cu alloys in inhibiting bacterial infections.

Candida albicans (CA) is a kind of fungus that can cause high morbidity and mortality in immunocompromised patients. However, preventing CA infection in these patients is still a daunting challenge. Herein, inspired from the fact that immunization with secreted aspartyl proteinases 2 (Sap2) can prevent the infection, it is proposed to use filamentous phage, a human-safe virus nanofiber specifically infecting bacteria (≈900 nm long and 7 nm wide), to display an epitope peptide of Sap2 (EPS, with a sequence of Val–Lys–Tyr–Thr–Ser) on its side wall and thus serve as a vaccine for preventing CA infection. The engineered virus nanofibers and recombinant Sap2 (rSap2) are then separately used to immunize mice. The humoral and cellular immune responses in the immunized mice are evaluated. Surprisingly, the virus nanofibers significantly induce mice to produce strong immune response as rSap2 and generate antibodies that can bind Sap2 and CA to inhibit the CA infection. Consequently, immunization with the virus nanofibers in mice dramatically increases the survival rate of CA-infected mice. All these results, along with the fact that the virus nanofibers can be mass-produced by infecting bacteria cost-effectively, suggest that virus nanofibers displaying EPS can be a vaccine candidate against fungal infection.

A facile method is needed to control the protein adsorption onto biomaterials, such as, bone implants. Herein we doped taurocholic acid (TCA), an amphiphilic biomolecule, into an array of 1D nano-architectured polypyrrole (NAPPy) on the implants. Doping TCA enabled the implant surface to show reversible wettability between 152° (superhydrophobic, switch-on state) and 55° (hydrophilic, switch-off state) in response to periodically switching two weak electrical potentials (+0.50 and −0.80 V as a switch-on and switch-off potential, respectively). The potential-switchable reversible wettability, arising from the potential-tunable orientation of the hydrophobic and hydrophilic face of TCA, led to potential-switchable preferential adsorption of proteins as well as cell adhesion and spreading. This potential-switchable strategy may open up a new avenue to control the biological activities on the implant surface.

An important criterion for effective gene therapy is sufficient chromosomal integration activity. The Sleeping Beauty (SB) transposon system is a plasmid system allowing efficient insertion of transgenes into the host genome. However, such efficient insertion occurs only after the system is delivered to nuclei. Since transposons do not have the transducing abilities of viral vectors, efficient delivery of this system first into cells and then into cell nuclei is still a challenge. Here, a phage display technique using a major coat displayed phage library is employed to identify a peptide (VTAMEPGQ) that can home to rat mesenchymal stem cells (rMSCs). A nanoparticle, called liposome protamine/DNA lipoplex (LPD), is electrostatically assembled from cationic liposomes and an anionic complex of protamine, DNA and targeting peptides. Various peptides are enveloped inside the LPD to improve its targeting capability for rMSCs and nuclei. The rMSC-targeting peptide and nuclear localization signal (NLS) peptide can execute the synergetic effect to promote transfection action of LPD. The homing peptide directs the LPD to target the MSCs, whereas the NLS peptide directs transposon to accumulate into nuclei once LPD is internalized inside the cells, leading to increased gene expression. This suggests that rMSC-targeting peptide and NLS peptide within LPD can target to rMSCs and then guide transposon into nuclei. After entering the nuclei, SB transposon increase the insertion rates into cellular chromosomes. The targeting LPD does not show obvious cell toxicity and influence on the differentiation potential of rMSCs. Therefore, the integration of SB transposon and LPD system is a promising nonviral gene delivery vector in stem cell therapy.

Viruses have recently proven useful for the detection of target analytes such as explosives, proteins, bacteria, viruses, spores, and toxins with high selectivity and sensitivity. Bacteriophages (often shortened to phages), viruses that specifically infect bacteria, are currently the most studied viruses, mainly because target-specific nonlytic phages (and the peptides and proteins carried by them) can be identified by using the well-established phage display technique, and lytic phages can specifically break bacteria to release cell-specific marker molecules such as enzymes that can be assayed. In addition, phages have good chemical and thermal stability, and can be conjugated with nanomaterials and immobilized on a transducer surface in an analytical device. This Review focuses on progress made in the use of phages in chemical and biological sensors in combination with traditional analytical techniques. Recent progress in the use of virus–nanomaterial composites and other viruses in sensing applications is also highlighted.

Viren haben sich in jüngster Zeit als einzigartige Hilfsmittel für den empfindlichen und selektiven Nachweis von Analyten wie Explosivstoffen, Proteinen, Bakterien, Viren, Sporen und Toxinen erwiesen. Auf Bakterien spezialisierte Viren, die Bakteriophagen – oder kurz Phagen –, wurden dabei am intensivsten untersucht: Zielspezifische nichtlysierende Phagen (sowie von diesen präsentierte Peptide und Proteine) können mithilfe hoch entwickelter Phagendisplaytechniken identifiziert werden, und lysierende Phagen können gezielt Bakterien aufbrechen und spezifische Zellmarker wie Enzyme ausschütten, die analysiert werden können. Darüber hinaus sind Phagen chemisch wie thermisch hinreichend stabil, und sie lassen sich mit Molekülen kuppeln und mit Nanomaterialien kombinieren und auf der Oberfläche eines Signalwandlers in einem Analysesystems verankern. Im Mittelpunkt dieses Aufsatzes stehen Fortschritte bei der Verwendung von Phagen in Chemo- und Biosensoren durch Kombination mit etablierten analytischen Techniken. Überdies werden aktuelle Entwicklungen bei der Verwendung von Virus-Nanomaterial-Kompositen und anderen Viren in Sensoranwendungen vorgestellt.

Bacterial flagellum is a protein nanotube that is helically self-assembled from thousands of a protein subunit called flagellin. The solvent-exposed domain of each flagellin on the flagella is genetically modifiable, in that a foreign peptide can be genetically inserted into this domain, leading to the high-density display of this foreign peptide on the surface of flagella. In this work, wild-type and genetically engineered flagella (inner diameter of ∼2 nm and outer diameter of ∼14 nm) detached from the surface of Salmonella bacterial cells are used as templates to site-specifically form silica sheaths on the flagellar surface, resulting in the formation of double-layered silica/flagella nanotubes. The flagella templates inside the silica/flagella nanotubes can be removed to obtain silica nanotubes by calcining the nanotubes at high temperature (550°C). Further calcination of the silica nanotubes at a higher temperature (800 °C) leads to the formation of a periodic nanohole array along the silica fibers with a center-to-center nanohole spacing of ∼79 nm. It is demonstrated that the double-layered silica-flagella nanotubes can be used for selective CdTe quantum dot uptake into the inner channels or selective Au nanoparticle coating on the outer wall of the nanotubes due to the different chemistry between inner flagellum core (protein) and outer silica wall of the nanotubes. It is also found that flagella displaying different peptides result in different morphologies of the silica nanotubes. This work suggests that the monodisperse diameter and genetically tunable surface chemistry of the flagella can be exploited for the fabrication of silica nanotubes with uniform diameter and controllable morphologies as well as silica nanofibers decorated with periodic nanohole arrays.