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Biolistic delivery is widely used for genetic transformation but inconsistency between bombardment samples for transient gene expression analysis often hinders quantitative analyses. We developed a methodology to improve the consistency of biolistic delivery results by using a double-barrel device and a cell counting software. The double-barrel device enables a strategy of incorporating an internal control into each sample, which significantly decreases variance of the results. The cell counting software further reduces errors and increases throughput. The utility of this new platform is demonstrated by optimizing conditions for delivering DNA using the commercial transfection reagent Trans IT-2020. In addition, the same approach is applied to test the efficacy of multiple gRNAs for CRISPR-Cas9-mediated gene editing. The novel combination of the bombardment device and analysis method allows simultaneous comparison and optimization of parameters in the biolistic delivery. The platform developed here can be broadly applied to any target samples using biolistics, including animal cells and tissues.

Achieving simultaneous high conductivity and mechanical durability in printed flexible electronics remains a central challenge. Here we report a systematic investigation of silver nanoparticle (AgNP) size effects on film performance using a pH-mediated synthesis that decouples particle size from organic content. This strategy enables direct assessment of size-dependent sintering and mechanical behaviors, previously obscured by varied polymer concentrations of traditional size control methods. With consistent organic content, AgNPs of smaller size demonstrated more effective sintering, forming denser and more cohesive microstructures, contrary to prior reports with varied organic concentration. This yielded highly conductive films with resistivities as low as 2.34 μΩ cm, approaching bulk silver. Additionally, electrohydrodynamic (EHD) printing of these inks produced flexible circuits with significantly improved mechanical resilience. The resistance of a printed pattern remained stable over 1,000 bending cycles at a 2.9 mm radius and increased by only 56.7% after 50,000 cycles, with no visible microstructural cracking.

Additive manufacturing as a method for producing electronic devices has seen significant growth in recent years, enabling simple, cost-effective, and sustainable processes. Electrohydrodynamic (EHD) printing is a promising additive manufacturing technique for producing microscale features with high precision. EHD also presents significant promise for use in microgravity, allowing for the on-demand fabrication of devices in outer-space missions. However, the selection of suitable inks remains a major challenge due to limited availability of formulations tailored for EHD processes. To address this, a new silver nano-ink platform was developed using a biobased polymer, 2-hydroxyethyl cellulose (HEC), which enables the in-situ synthesis and long-term stabilization of silver nanoparticles. This approach offers advantages over conventional polymer stabilizers, including cost, efficiency, and sustainability, while supporting high solids content and low-temperature sintering, making it well-suited for flexible electronics. The silver ink developed in this work was verified for smooth EHD printing, including in microgravity. In addition, a systematic study of nanoparticle size was conducted to understand its influence on the electrical and mechanical performance of printed films. While traditional synthesis methods rely on adjusting organic content to tune particle size, the presented platform offers tunability through a pH-mediated approach, allowing for independent control of both factors, and resulting in trends not previously reported. The results of this study were leveraged to optimize the electrical performance and mechanical durability of inks in flexible circuits, enabling robust printed features that perform reliably over 10,000s of deformation cycles. Finally, the conductive polymer PEDOT:PSS was investigated for incorporation into the ink platform to develop a high-solids silver ink that displays high conductivity without requiring any sintering step. Together, these developments offer a versatile and scalable solution for advancing sustainable, flexible, high-performance, and space-deployable electronics.