A study on biological sample preparation for high resolution imaging of scanning electron microscope

Abstract

Green chemistry has drawn attention for synthesizing nanoparticles as it utilizes an eco-friendly nontoxic chemical in the synthesis protocol. In addition, researchers start looking into the potential of organism such as bacteria, fungi and plants for synthesizing nanoparticles. Synthesis of nanoparticles requires details on structural analysis before/after synthesis in order to evaluate and control the quality of nanoparticles. Scanning electron microscope (SEM) has been widely used as an imaging instrument to structurally characterize nanoparticles before/after synthesis process. Maintaining the vacuum level in SEM system and controlling contamination originated from the sample are crucially important to enable high resolution imaging. In addition, sample surface need to be conductive to prevent image distortion due to the electron charging effect. Hence, raise the importance to study the method in preparing biological sample for SEM imaging. This work focuses on the three approaches of drying process for plant, bacteria and algae samples. Proper selection of preparation method on each samples involving air-drying using HMDS, CPD and FD methods have been done in order to prevent surface tension effect during drying process, which will result in the modification of the original structure. Comparison was made to get insight on the suitable sample preparation method for the specific biological sample. It is found that air-drying or CPD methods are suitable for the liquid-rich biological sample, while FD method can be a preference for biological sample that contains less liquid.