This review gives an overview of techniques used for high-resolution jet printing that rely on electrohydrodynamically induced flows. Such methods enable the direct, additive patterning of materials with a resolution that can extend below 100 nm to provide unique opportunities not only in scientific studies but also in a range of applications that includes printed electronics, tissue engineering, and photonic and plasmonic devices. Following a brief historical perspective, this review presents descriptions of the underlying processes involved in the formation of liquid cones and jets to establish critical factors in the printing process. Different printing systems that share similar principles are then described, along with key advances that have been made in the last decade. Capabilities in terms of printable materials and levels of resolution are reviewed, with a strong emphasis on areas of potential application.

Mechanisms, Capabilities, and Applications of High-Resolution Electrohydrodynamic Jet Printing.

Bacterial resistance is a major problem in the modern world, stemming in part from the build-up of antibiotics in the environment Novel molecular approaches that enable an externally triggered increase in antibiotic activity with high spatiotemporal resolution and auto-inactivation are highly desirable Here we report a responsive, broad-spectrum, antibacterial agent that can be temporally activated with light, whereupon it auto-inactivates on the scale of hours The use of such a 'smart' antibiotic might prevent the build-up of active antimicrobial material in the environment Reversible optical control over active drug concentration enables us to obtain pharmacodynamic information Precisely localized control of activity is achieved, allowing the growth of bacteria to be confined to defined patterns, which has potential for the development of treatments that avoid interference with the endogenous microbial population in other parts of the organism

Optical control of antibacterial activity

Electrohydrodynamic atomization: A two-decade effort to produce and process micro-/nanoparticulate materials.

Carbon nanotubes (CNTs) have been widely used in a variety of applications because of their unique structure and excellent mechanical and electrical properties. Additionally, silver (Ag) nanoparticles exhibit broad-spectrum biocidal activity toward many different bacteria, fungi, and viruses. In this study, we prepared Ag-coated CNT hybrid nanoparticles (Ag/CNTs) using aerosol nebulization and thermal evaporation/condensation processes and tested their usefulness for antimicrobial air filtration. Droplets were generated from a CNT suspension using a six-jet collison nebulizer, passed through a diffusion dryer to remove moisture, and entered a thermal tube furnace where silver nanoparticles were generated by thermal evaporation/condensation at ∼980 °C in a nitrogen atmosphere. The CNT and Ag nanoparticle aerosols mixed together and attached to each other, forming Ag/CNTs. For physicochemical characterization, the Ag/CNTs were introduced into a scanning mobility particle sizer (SMPS) for size distribution measurements and were sampled by the nanoparticle sampler for morphological and elemental analyses. For antimicrobial air filtration applications, the airborne Ag/CNT particles generated were deposited continuously onto an air filter medium. Physical characteristics (fiber morphology, pressure drop, and filtration efficiency) and biological characteristics (antimicrobial tests against Staphylococcus epidermidis and Escherichia coli bioaerosols) were evaluated. Real-time SMPS and transmission electron microscopy (TEM) data showed that Ag nanoparticles that were <20 nm in diameter were homogeneously dispersed and adhered strongly to the CNT surfaces. Because of the attachment of Ag nanoparticles onto the CNT surfaces, the total particle surface area concentration measured by a nanoparticle surface area monitor (NSAM) was lower than the summation of each Ag nanoparticle and CNT generated. When Ag/CNTs were deposited on the surface of an air filter medium, the antimicrobial activity against test bacterial bioaerosols was enhanced, compared with the deposition of CNTs or Ag nanoparticles alone, whereas the filter pressure drop and bioaerosol filtration efficiency were similar to those of CNT deposition only. At a residence time of 2 h, the relative microbial viabilities of gram-positive S. epidermidis were ∼32, 13, 5, and 0.9% on the control, CNT-, Ag nanoparticle-, and Ag/CNT-deposited filters, respectively, and those of gram-negative E. coli were 13, 2.1, 0.4, and 0.1% on the control, CNTs, Ag nanoparticles, and Ag/CNTs, respectively. These Ag/CNT hybrid nanoparticles may be useful for applications in biomedical devices and antibacterial control systems.

Preparation of Airborne Ag/CNT Hybrid Nanoparticles Using an Aerosol Process and Their Application to Antimicrobial Air Filtration

Poor air hygiene as a result of bioaerosol contamination has caused diverse forms of adverse health effects and diseases. In addition, global biosecurity is threatened by purposeful use of biowarfa...

https://www.tandfonline.com/doi/pdf/10.1080/02786826.2011.593591

Bioaerosol Science, Technology, and Engineering: Past, Present, and Future

In this study, the drop-on-demand patterning of bacterial cells on a raw silicon wafer was newly conducted with an electrospray pulsed jet. We produced various sized line patterns and spot patterns of bacterial cells on the silicon wafer under varying experimental conditions of frequency, flow rate, and translational speed of the electrospray system in one and two-dimensional ways. Especially, the electrospray’s pulsed jet of bacterial solution produced regular patterns of around 10 μm diameter spots, each of which contained a single bacterial cell. By enabling drop-on-demand patterning and manipulation of single bacterial cells on a raw wafer in the gas phase, this new technique broadens the scope of biological experiments beyond liquid phase treatments to solid and gas-phase treatments.

Jun Hyun Lee

Papers

Drop-on-demand patterning of bacterial cells using pulsed jet electrospraying.

Design and characterization of a fungal bioaerosol generator using multi-orifice air jets and a rotating substrate

Use of an electrospray for the generation of bacterial bioaerosols

Generation characteristics of fungal spore and fragment bioaerosols by airflow control over fungal cultures