Control of stem cell fate by modulating biophysical cues (e.g., micropatterns, nanopatterns, elasticity and porosity of the substrates) has emerged as an attractive approach in stem cell-based research. Here, we report a method for fabricating combinatorial patterns of graphene oxide (GO) to effectively control the differentiation of human adipose-derived mesenchymal stem cells (hADMSCs). In particular, GO line patterns were highly effective for modulating the morphology of hADMSCs, resulting in enhanced differentiation of hADMSCs into osteoblasts. Moreover, by generating GO grid patterns, we demonstrate the highly efficient conversion of mesodermal stem cells to ectodermal neuronal cells (conversion efficiency = 30%), due to the ability of the grid patterns to mimic interconnected/elongated neuronal networks. This work provides an early demonstration of developing combinatorial graphene hybrid-pattern arrays for the control of stem cell differentiation, which can potentially lead to more effective stem cell-based treatment of incurable diseases/disorders.

Nucleic acid biomarkers have been widely used to detect various viral-associated diseases, including the recent pandemic COVID-19. The CRISPR-Cas-based trans-activating phenomenon has shown excellent potential for developing sensitive and selective detection of nucleic acids. However, the nucleic acid amplification steps are typically required when sensitive and selective monitoring of the target nucleic acid is needed. To overcome the aforementioned challenges, we developed a CRISPR-Cas12a-based nucleic acid amplification-free biosensor by a surface-enhanced Raman spectroscopy (SERS)-assisted ultrasensitive detection system. We integrated the activated CRISPR-Cas12a by viral DNA with a Raman-sensitive system composed of ssDNAimmobilized Raman probe-functionalized Au nanoparticles (RAuNPs) on the graphene oxide (GO)/triangle Au nanoflower array. Using this CRISPR-based Raman-sensitive system improved the detection sensitivity of the multiviral DNAs such as hepatitis B virus (HBV), human papillomavirus 16 (HPV-16), and HPV-18 with an extremely low detection limit and vast detection range from 1 aM to 100 pM without the amplification steps. We suggest that this ultrasensitive amplification-free detection system for nucleic acids can be widely applied to the precise and early diagnosis of viral infections, cancers, and several genetic diseases.

A novel cell-based biosensing platform (Large-scale Homogeneous Nanoelectrode Arryas, LHONA) is developed using a combination of sequential laser interference lithography and electrochemical deposition methods. This enables the sensitive discrimination of dopaminergic cells from other types of neural cells in a completely non-destructive manner owing to its enhanced biocompatibility and excellent electrochemical properties. As such, this platform/detection strategy holds great potential as an effective non-invasive in situ monitoring tool that can be used to determine stem cell fate for various regenerative applications.

The detection of nucleic acids and their mutation derivatives is vital for biomedical science and applications. Although many nucleic acid biosensors have been developed, they often require pretreatment processes, such as target amplification and tagging probes to nucleic acids. Moreover, current biosensors typically cannot detect sequence-specific mutations in the targeted nucleic acids. To address the above problems, herein, we developed an electrochemical nanobiosensing system using a phenomenon comprising metal ion intercalation into the targeted mismatched double-stranded nucleic acids and a homogeneous Au nanoporous electrode array (Au NPEA) to obtain (i) sensitive detection of viral RNA without conventional tagging and amplifying processes, (ii) determination of viral mutation occurrence in a simple detection manner, and (iii) multiplexed detection of several RNA targets simultaneously. As a proof-of-concept demonstration, a SARS-CoV-2 viral RNA and its mutation derivative were used in this study. Our developed nanobiosensor exhibited highly sensitive detection of SARS-CoV-2 RNA (∼1 fM detection limit) without tagging and amplifying steps. In addition, a single point mutation of SARS-CoV-2 RNA was detected in a one-step analysis. Furthermore, multiplexed detection of several SARS-CoV-2 RNAs was successfully demonstrated using a single chip with four combinatorial NPEAs generated by a 3D printing technique. Collectively, our developed nanobiosensor provides a promising platform technology capable of detecting various nucleic acids and their mutation derivatives in highly sensitive, simple, and time-effective manners for point-of-care biosensing.

The emergence of nanotechnology has created unprecedented hopes for addressing several unmet industrial and clinical issues, including the growing threat so-termed "antibiotic resistance" in medicine. Over the last decade, nanotechnologies have demonstrated promising applications in the identification, discrimination, and removal of a wide range of pathogens. Here, recent insights into the field of bacterial nanotechnology are examined that can substantially improve the fundamental understanding of nanoparticle and bacteria interactions. A wide range of developed nanotechnology-based approaches for bacterial detection and removal together with biofilm eradication are summarized. The challenging effects of nanotechnologies on beneficial bacteria in the human body and environment and the mechanisms of bacterial resistance to nanotherapeutics are also reviewed.