Fiber-optic photoacoustic enables targeted neuromodulation and stress reduction in mice

• • The FPE achieves a 200 µm diameter, enabling access to deep or confined anatomical regions with minimal trauma, which is critical for clinical translation in minimally invasive procedures where probe size directly impacts patient recovery and tissue damage. • • The device generates ultrasound pressures up to several MPa and bandwidths exceeding 20 MHz, providing sufficient acoustic intensity for neuromodulation and high-resolution imaging, with direct implications for both therapeutic efficacy and diagnostic capability in neuropsychiatric disorders. • • Ti3C2Tx MXene composite exhibits excellent photothermal stability under repeated 1064 nm near-infrared radiation, allowing continuous laser pulses without degradation, which ensures consistent ultrasound emission over prolonged stimulation periods, a key requirement for chronic neuromodulation therapies. • • In vivo stimulation of the medial prefrontal cortex in mice resulted in marked alleviation of acute social defeat stress-induced emotional stress, evidenced by reduced anxiety-like behavior and increased social interaction, demonstrating translational potential for treating stress-related neuropsychiatric conditions such as anxiety and depression.