{"id":"20251037-e743-4b82-9dd9-88a70c3ebaaf","arxiv_id":"2504.21434","paper_version":1,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":7.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":2,"one_line_summary":"A light-driven rotary motor was integrated into a DNA origami device via four-point conjugation, and single-molecule tracking showed UV-triggered rotation of an attached DNA rotor arm in a subset of devices.","lead":"The paper shows a synthetic light-driven molecular motor can be attached to DNA nanostructures at four defined points and coupled to a fluorescent DNA lever arm, allowing its rotation to be followed with a microscope. A small fraction of the assembled devices rotated when exposed to UV light, suggesting a programmable route to light-powered nanomachines.","discovery_kind":"new_method","skeptic_critique":{"model":"deepseek-v4-flash","headline":"Actuation claim depends on a modest tail excess and on trajectory classes selected from pre-identified rotators, leaving the UV-synchronized directional evidence vulnerable to selection bias.","rationale":"The reader identified the core risk: the excess of high-displacement full-assembly devices over controls might be explained by control-like random motion rather than motor activity, especially given the admitted false positives in Figure S20. I agree that this is the central load-bearing assumption. I would sharpen it further: the paper's supportive trajectory-level evidence is potentially circular because the angular traces and rotation-rate comparisons are computed only for particles that were pre-selected as rotating from prior localization data (SI section VI.4). Thus, even if the aggregate excess is statistically significant, the temporal synchronization and directionality evidence could be an artifact of choosing particles that display the desired behavior. This does not move the verdict because the reader already set CONDITIONAL with medium risk; my concern reinforces the same conditionality rather than changing it. The concrete test would settle the issue by applying a fixed classifier to all devices, not just selected rotators, and by testing the UV-on/off difference within the full population. If the effect survives that test, the actuation claim would be substantially strengthened; if not, the central claim would need to be scaled back to a framework demonstration only.","tokens_in":37332,"tokens_out":9302,"duration_ms":103877,"concrete_test":"Reanalyze all tracked devices in the multi-pulse UV condition with no manual pre-selection, applying a fixed, pre-registered classifier: net angular displacement >75°, sign consistency (no net reversal exceeding 180° cumulative), and ≥50% of accumulated angular change occurring during UV-on frames. Compare the proportion passing in full-assembly (N=981) vs single-leg (N=334), single-arm (N=855), and no-UV full-assembly (N=229) conditions with a permutation test. If the full-assembly UV proportion is not significantly higher than every control and than no-UV full assembly, and if the UV-on vs UV-off rotation rates in the full sample (not just selected rotators) show no significant difference, then the actuation claim is unsupported.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The central claim, that rotor motion is driven by light-activated motor rotation, rests on two evidentiary layers. The first is the aggregate excess of >75° displacements in fully assembled devices under multi-pulse UV (5.1%, N=981) compared with controls (2.1% single-leg, 2.1% single-arm; Fig. 4b, Figs. S17-S19). This excess is interpreted as motor-driven, yet the paper itself states that some full-assembly trajectories 'may represent false positives retained through histogram-based filtering' (Figure S20). The second layer consists of example trajectories showing UV-synchronized directional rotation (Figs. 4e-f, 5a-b). Those examples are drawn from 'particles pre-selected from prior localization data' (SI section VI.4), with no pre-defined criterion for distinguishing genuine motor-driven traces from false positives. The reported UV-on vs UV-off rotation rates (0.213 vs 0.087 rotations/sec) are computed from this pre-selected group, so they cannot independently establish that UV causes the rotation; the selection and the measurement are circular. Without counts of how many of the 50 multi-pulse high-displacement devices fall into the directional, stepping, and control-like classes, and without a fixed classification rule applied uniformly to full and control groups, the excess could reflect a few genuine events mixed with a larger number of false positives. This is the load-bearing weak point for the actuation claim.","agreement_with_reader":"partial"},"referee_report":{"model":"deepseek-v4-flash","summary":"The manuscript reports the integration of a light-driven second-generation molecular motor into DNA origami-based rotary devices. The motor is site-specifically conjugated to four distinct DNA adapters using a two-template conjugation strategy, and the resulting motor-ABCD construct is used to link a baseplate (or, in a simplified design, a biotinylated DNA anchor) to a 10-helix-bundle rotor arm. The authors track the fluorescently labeled rotor arm by TIRF microscopy at 100 Hz, classify devices by net angular displacement, and report that fully assembled devices show a higher fraction of large angular displacements under UV illumination than single-leg or single-arm controls. A subset of trajectories show UV-synchronized directional rotation or stepwise transitions. The paper claims that these observations support light-activated motor rotation mechanically coupled to the DNA rotor.","tokens_in":37617,"tokens_out":2181,"duration_ms":25958,"significance":"If the actuation claim is established, the paper would provide a valuable modular framework for integrating synthetic molecular motors into DNA nanomachines and for single-molecule studies of motor mechanics. The conjugation chemistry is a genuine technical achievement: the two-template strategy is well evidenced by PAGE, HPLC, complement-hybridization tests, and the assembly of the full device is supported by agarose gels and TEM. The work also contributes a detailed negative-control design (single-leg and single-arm constructs). However, the central functional claim currently rests on a small excess of large-displacement events and on trajectories selected with criteria that are not fully objective, so the significance of the paper as a demonstration of motor-driven actuation is not yet established. The framework itself is plausible and the evidence for conjugation and assembly is strong, which makes the paper suitable for revision rather than rejection.","major_comments":[{"comment":"The headline quantitative evidence for motor-driven actuation is the excess of devices with net angular displacement >75° in fully assembled devices under multiple UV pulses (5.1%, N=981) compared with single-leg and single-arm controls (2.1% each). No error bars, confidence intervals, replicate experiments, or significance tests are reported for these fractions. Given the modest difference and the large sample sizes, the authors should provide a statistical test (e.g., chi-square or bootstrap) with p-values and confidence intervals. The concern is amplified by the authors' own statement in the section on device motion classes that some high-displacement full-assembly trajectories 'may represent false positives retained through histogram-based filtering' (Figure S20). Since the classification threshold of 25°/75° is also hand-chosen, the 5.1% vs 2.1% comparison is not currently load-bearing evidence for motor-driven rotation.","section":"Motion Analysis; Fig. 4b; Figs. S17-S19"},{"comment":"The UV-synchronized directional trajectories and the quantitative rates (0.213 rotations/sec with UV on vs 0.087 rotations/sec with UV off) are computed from particles that were 'pre-selected from prior localization data' (SI Section VI.4). No pre-defined, objective criterion is given for selecting these particles, and the same selection is not applied to the control trajectories. This makes the selection and the measured UV effect circular: one cannot independently establish that UV causes the rotation if the analyzed subset was chosen by visual inspection of UV-correlated behavior. The authors should define a fixed classification rule (e.g., based on sign of angular velocity during UV-on intervals, fraction of UV-on frames with same-sign steps, or a step-detection criterion), apply it blindly to full-assembly and control traces, and report how many of the 50 high-displacement devices fall into each class (directional, stepping, control-like).","section":"SI Section VI.4; Figs. 4e-f; Figs. 5a-b"},{"comment":"The angular unwrapping procedure assumes that angular changes between consecutive frames do not exceed 180°. The authors acknowledge that for large discontinuities it is 'difficult to determine unambiguously the direction and number of full rotations.' This ambiguity directly affects the reported rotation rates and directionality claims for the selected directional trajectories. The authors should either restrict the quantitative directional analysis to traces for which the stepwise assumption is explicitly validated (e.g., by checking that the distribution of frame-to-frame angular steps is unimodal and below 180°), or perform a sensitivity analysis that quantifies how many alternative unwrappings are consistent with the reported rates and step directions.","section":"SI Section VI.4; Fig. 4d"}],"minor_comments":[{"comment":"The initial 'single device' observation under continuous UV (Fig. 3h, arrow; Fig. 3i-j) is presented as consistent with a 120° photoisomerization step followed by a 60° thermal helix inversion, but no statistics or additional examples are given. This should be explicitly labeled as a preliminary observation, not as evidence for the actuation mechanism.","section":"Fig. 3h-i"},{"comment":"The displacement thresholds (<25°, 25-75°, >75°) are introduced without justification. The authors should either justify these values from the localization precision and rotor geometry or show that the conclusions are robust to reasonable threshold variations.","section":"Motion Analysis; Fig. 4b"},{"comment":"The sentence describing 4HB devices as displaying 'switching behaviour, consistent with ~180° rotation' is vague about whether these events occur in the negative-control configurations; please clarify whether the same switching was observed in controls, since this affects the interpretation of the subsequent simplified-system design.","section":"Results, 'Optical Tracking'"},{"comment":"The simplified-device assembly uses a 0.5:1 motor-to-rotor-arm ratio and 5:1 for the biotinylated strands, but the manuscript does not report the efficiency of full motor incorporation in the simplified devices (e.g., how many devices actually contain a motor as opposed to broken or partially conjugated constructs). A gel or single-molecule occupancy estimate would strengthen the connection between device architecture and observed motion.","section":"SI Methods 12.2"},{"comment":"There are several typographical and formatting issues, including 'statys' in the SI, inconsistent figure labeling (two Figures labeled S8), and the incomplete TEM methods sentence '(to be checked)'. These should be corrected in revision.","section":"Throughout"}],"recommendation":"major_revision","confidential_remarks":"The manuscript is a good fit for the journal's applied-physics/nanotechnology scope, and the conjugation and assembly work is solid. My main reservation is that the central actuation claim is not yet quantitatively secure: the aggregate comparison lacks statistical testing, the trajectory-level analysis is based on pre-selected particles, and the unwrapping assumption creates ambiguity in the reported rates. These issues are fixable with additional analysis of the existing data, which is why I recommend major revision rather than rejection. I would also encourage the editor to ensure that the final version includes the underlying tracking data or a clear data-availability statement, since the paper's value depends heavily on single-molecule trajectory evidence."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Colleague,\n\nWhat you should know about this paper: the real advance is in the chemistry, not the physics. The four-point conjugation of a synthetic rotary motor to DNA adapters—two CuAAC, two amide, with the two-template rescue when the second conjugation step failed—is a solid, reproducible-looking method, well-evidenced by PAGE, HPLC, complement hybridization and TEM. That part deserves attention.\n\nThe actuation claim is softer. The headline result is a small excess of large angular displacements in fully assembled devices under multi-pulse UV (5.1% of 981 vs 2.1% for both controls). No error bars or significance tests are given, and although a quick chi-square would probably show some difference, the more serious problem is the interpretation. The paper itself admits that some full-assembly trajectories may be false positives retained through histogram-based filtering (Fig. S20). The example trajectories showing UV-synchronized rotation are taken from particles pre-selected from prior localization data, with no fixed classification rule applied to both full and control groups. The UV-on vs UV-off rotation rates (0.213 vs 0.087 rotations/s) are computed from that pre-selected group, so they cannot independently confirm that UV drives the rotation; the selection and the measurement are circular. The unwrapping assumption (<180°/frame) adds further ambiguity, as the authors acknowledge.\n\nThat said, the paper is not sloppy. The authors are explicit about the false positives, the failed second conjugation attempts, and the ambiguity in the angular traces. The controls are reasonable. The problem is a mismatch between the strength of the claim ('directional motion ... driven by light-activated rotation') and the strength of the statistical evidence.\n\nWho should read it: people working on DNA-origami integration of molecular motors, and anyone interested in single-molecule assay design. The conjugation framework could be cited and used directly; the actuation result should be treated as suggestive until the analysis is tightened.\n\nFor peer review: yes, it deserves a serious referee. The chemistry is a genuine contribution, and the actuation question is important enough to warrant revision rather than rejection. The authors should be asked to apply a pre-defined, blind classification to all trajectories, report counts and error bars, and show the UV-on/off comparison as a difference-in-differences across full and control groups.","headline":"The four-point motor-DNA conjugation is a solid, citable contribution; the single-molecule actuation evidence is suggestive but rests on circular trajectory selection.","tokens_in":38142,"tokens_out":2550,"would_cite":true,"duration_ms":27012,"reading_group":"maybe","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"deepseek-v4-flash","headline":"A synthetic rotary motor is mechanically coupled to a DNA origami rotor and driven by UV light, with the rotation tracked at the single-molecule level.","keywords":["DNA origami","molecular motor","light-driven rotation","single-molecule tracking","TIRF microscopy","DNA-templated conjugation","rotary actuator","nanoscale actuation"],"falsifier":"Track fully assembled devices under multi-pulse UV with a motor whose central double bond cannot photoisomerize (for example, a hydrogenated analogue): if the fraction of devices with more than 75° displacement stays near 5%, the motor-driven interpretation is wrong; if it falls to the control level of about 2%, the claim is supported.","tokens_in":37154,"feed_emoji":"🧬","tokens_out":7981,"duration_ms":76048,"temperature":0.7,"pith_summary":"The paper sets out to show that a light-driven synthetic rotary motor can be wired into a larger DNA nanomechanical device so that its molecular-scale rotation is amplified into a visible swing of a fluorescent rotor arm. The authors attach four distinct DNA handles to the motor's stator and rotor, dock the stator to a surface anchor and the rotor to a stiff DNA arm by hybridization, and watch individual arms under a TIRF microscope while pulsing UV light. They report a subset of fully assembled devices whose angular trajectories show directional rotation and discrete steps aligned with UV pulses, with a larger fraction of large angular displacements than broken-connection controls (5.1% vs 2.1% after multiple UV pulses). If correct, this gives a programmable framework for integrating synthetic motors into DNA nanomachines and for studying motor mechanics one molecule at a time.","feed_headline":"UV light spins a DNA rotor powered by a molecular motor","feed_subtitle":"Four DNA handles wire a synthetic motor into an origami arm, and single-molecule tracking catches UV-triggered steps.","key_machinery":"The load-bearing mechanism is a four-point, site-specific conjugation of the motor to DNA: copper-catalysed azide-alkyne cycloaddition (CuAAC) attaches two adapters to the stator, amide coupling attaches two adapters to the rotor, and a two-template strategy overcomes steric hindrance that blocks sequential addition. These adapters allow the motor to be the only mechanical link between a biotin-streptavidin surface anchor and a ~280 nm 10-helix-bundle rotor arm, so motor rotation changes the arm's azimuth. The arm's distal Cy3 fluorescence is localized at 100 Hz and fitted to a circular trajectory, converting sub-nanometre motor steps into resolvable angular motion.","core_discovery":"On the paper's own terms, the central claim is that a second-generation overcrowded-alkene rotary motor, site-specifically conjugated to four DNA adapters and hybridized between a surface anchor and a stiff 10-helix-bundle DNA rotor arm, transduces 366 nm UV light into unidirectional rotation of the rotor arm that can be followed in real time by fluorescence localization. The evidence is a small but distinct population of devices whose motion is temporally aligned with UV exposure, including one trajectory with an approximate 120° step followed by a 60° step, consistent with photoisomerization followed by thermal helix inversion. The reported average rotation rate during UV illumination was 0.213 rotations/s (76.7°/s), versus 0.087 rotations/s (31.4°/s) with UV off, while control devices with a broken motor connection showed no such UV-correlated excess. The paper concludes that directional motion arises specifically from motor activity.","pith_inferences":["If the 5.1% versus 2.1% excess is genuine motor actuation, stiffer coupling and reduced rotor-surface friction should push the active fraction well above 5%, a concrete design rule the paper leaves implicit.","The same four-point conjugation could be used to mount unrelated rotary or linear motors into the identical origami chassis, turning the platform into a comparative test bed for motor designs.","A directional-bias statistic applied to the ambiguous full-assembly traces (Figure S20) might separate true motor-driven events from random-walk false positives without collecting more data.","The one observed 120° plus 60° trajectory suggests the rotor arm may report individual photochemical half-cycles, which could be used to measure the angular distribution of motor steps under load."],"forward_implications":["The four-adapter conjugation is a modular interface that should place other synthetic rotary motors into DNA nanostructures with defined orientation.","Single-molecule tracking of the rotor arm can resolve individual motor steps, such as the reported 120°/60° sequence, enabling direct study of motor photophysics under mechanical load.","The device design demonstrates that mechanical compliance between motor and rotor strongly affects whether motor rotation appears in the arm's motion.","Even with a minority of devices showing activity, the UV-correlated directional trajectories provide a statistical signature that distinguishes motor-driven rotation from control-like random motion."],"supporting_citations":[{"why":"Supplies the DNA-templated conjugation chemistry used to attach the first pair of adapters to the motor.","marker":"49"},{"why":"Defines the light-driven motor's photoisomerization and thermal helix inversion rotation cycle used as the actuator.","marker":"8"},{"why":"Provides prior single-molecule motor step-size and direction data that the observed 120° and 60° steps are compared with.","marker":"17"},{"why":"Provides the localization algorithm used to track rotor-arm fluorescence at 100 Hz.","marker":"50"},{"why":"Supports the claim that the 10-helix-bundle rotor arm is rigid enough for reliable circular-trajectory fitting.","marker":"51"},{"why":"Precedent for using DNA origami rotors to track rotational motion of a motor at the single-molecule level.","marker":"33"}],"fun_headline_variants":["UV light spins a DNA rotor via a synthetic motor","Single-molecule tracking reveals UV-driven DNA rotor","Four-point conjugation wires molecular motor into DNA","Synthetic motor drives DNA rotor arm under UV","Light-driven rotary motor rotates DNA nanostructure"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The claim stands on the assumption that the excess of large angular displacements in fully assembled devices (5.1% under multi-pulse UV versus 2.1% in controls) is caused by motor-driven rotation, rather than by the same control-like random motion that the paper itself flags as possible false positives in its Figure S20.","fun_headline_variants_meta":{"raw":{"variants":["UV light spins a DNA rotor via a synthetic motor","Single-molecule tracking reveals UV-driven DNA rotor","Four-point conjugation wires molecular motor into DNA","Synthetic motor drives DNA rotor arm under UV","Light-driven rotary motor rotates DNA nanostructure"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.00026,"raw_usage":{"total_tokens":1595,"prompt_tokens":957,"completion_tokens":638,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":573,"completion_tokens_details":{"reasoning_tokens":568}},"tokens_in":573,"tokens_out":638,"duration_ms":6473,"temperature":1.0,"reasoning_tokens":568,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-16T05:03:53.079130+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Track fully assembled devices under multi-pulse UV with a motor whose central double bond cannot photoisomerize (for example, a hydrogenated analogue): if the fraction of devices with more than 75° displacement stays near 5%, the motor-driven interpretation is wrong; if it falls to the control level of about 2%, the claim is supported.","supporting_citations":[],"review_version":1}