1. Molecular binding such as the toehold-mediated strand displacement (TMSD) method in DNA tweezers (Fig. ) , , , and aptamer binding in a logic-gated nanorobot (Fig. ) . In another study, conformational changes were investigated via releasing or locking strands in a reconfigurable DNA origami tripod with gold nanorods . It can be also exploited in changing the morphology in the nanoscale by triggering strands (Fig. ) . Catalytic actuation by the activity of an enzyme attached to different arms of a DNA tweezer can also help in designing nanoreactors[72] 2. Environmental stimuli such as reversibly salt-based actuation, capable of response times in the range of hundreds of milliseconds (Fig. ) or a DNA origami nanoactuator that is responsive to the ions, proteins, or nucleic acids stimuli (Fig. ) , pH-based actuation in a reconfigurable DNA Origami nanocapsule , optical-based actuation in a DNA origami sphere via incorporation of fluorescencecleavable spacers (Fig. ) or hybridization and dehybridization of azobenzenemodified DNA oligonucleotides with chiral properties via UV/VIS stimuli . The chiroptical properties have been also investigated in biosensing engineering by DNA nanotechnology[78] 3. External field actuation such as reversibly thermal actuation in a DNA nanovalve that exhibits a bulk response time in the range of tens of minutes (Fig. ) , electric field actuation in a switchable controlled rotating robotic arm on order hundreds of milliseconds (Fig. ) , magnetic actuation in a DNA origami assembly of stiff micro-levers with adjustable rotational speed and a rapid response time in the range of hundreds of milliseconds . In addition to conformational changes, the conductivity of the DNA origami nanopores can be regulated by the applied voltage (Fig. ) , , Figure -mechanisms applied in dynamic DNA nanodevices: 1. Molecular interaction with a trigger e.g. A) a DNA tweezer that can be changed from close to open by the addition of an oligonucleotide strand , B) An automomous DNA nanorobot, regulated by a logic gate encoded in an aptamer, can be maintained in a separated state through its interaction with an antigen key and C) a rectangular array of double-stranded DNA that switches into the alternative stable configuration through a "domino array" transformation when it is triggered by an oligonucleotide strand. 2. Environmental stimuli e.g. D) a DNA origami hinge with single-stranded DNA overhangs sensitive to cation concentrations in solution which results in the hybridization of DNA overhangs closing and opening transitions occur on the millisecond time scale , E) A rhombus-shaped DNA origami "nanoactuator" whose shape could be accurately adjusted using "strut -locking" strands, transitioning from a closed configuration to an open configuration by modifying the length of the connecting struts , and F) a DNA origami sphere that can be transformed into two tethered hemispheres using light to trigger photo-cleavable spacers within the short oligonucleotide strands connecting adjacent helices . 3. External field actuation e.g. G) a multifunctional nanovalve that is closed at ambient temperatures and its programmable thermosensitive lid opens the barrel above 40 °C to allow transport of small molecules across the membrane , H) a DNA-based square with an integrated robotic arm that can be switched by externally applied electrical fields between arbitrary positions within milliseconds, and I) a DNA origami nanopores with a long double-stranded DNA leash combined with glass nanocapillaries that can have conformation change under applied voltages . Figures were sketched with All of these recent advances in DNA nanotechnology have shown great promise in creating encoded machines with complex molecular structures and machine-like functions Due to the high programmability and versatility of the DNA that can be engineered to self-assemble into complex structures and act as a scaffold for other molecules to bind to , , the custom DNA nanostructures have immense potential for applications across various fields, including biology, chemistry, and engineering by a wide range of DNA-based nanodevices, including motors, switches, sensors, and more . Thus, they could be used as tools for both studying the behavior of living systems and developing new drug delivery systems that can be actuated and move and target specific cells or tissues. A prominent prototype of such a drug carrier is a logic-gated origami hexagonal barrel, containing antibody fragments, locked with aptamers to hold the two halves together. When the aptamer target, such as a cell receptor, binds to the aptamers, it acts as a lock and key, and the barrel unlocks and exposes its antibody cargo. This enables the antibodies to bind to a different set of receptors, as demonstrated through cell labeling and receptor-mediated signaling pathways .