Table 5.

Some application scenarios and studies about nanorobots for precision surgery

Surgery type	Author	Nanorobot name	Exploration details	Key highlights of nanorobot in surgery	Refs.
Biopsy/sample collection	Breger et al.	Self-folding thermo-magnetically responsive soft microgrippers	Using experiments and modeling, the authors designed, fabricated, and characterized photopatterned, self-folding functional microgrippers that combine a swellable, photo-cross-linked pNIPAM-AAc soft-hydrogel with a nonswellable and stiff segmented polymer (polypropylene fumarate, PPF) They also showed that we can embed iron oxide (Fe2O3) nanoparticles into the porous hydrogel layer, allowing the microgrippers to be responsive and remotely guided by external magnetic fields	Due to the low modulus of hydrogels such as poly(N-isopropylacrylamide-co-acrylic acid) (pNIPAM-AAc), they have limited gripping ability of relevance to surgical excision or robotic tasks such as pick-and-place. This nanorobot helps resolve the problem to some extent This study illustrated operation and functionality of these polymeric microgrippers for soft robotic and surgical applications	[299]
	Fernando Soto et al.	Multifunctional onion-like microtrap vehicle	The onion-inspired multi-layer structure contains a magnesium engine core and several outer chemoattractant and therapeutic layers Upon chemical propulsion, the magnesium core is depleted, resulting in a hollow structure that exposes the inner layers and serves as structural trap	The development of a multifunctional motile microtrap is capable of autonomously attracting, trapping and destroying of pathogens through controlled chemoattractant and therapeutic agent release Such a built-in chemical communication between synthetic microswimmers and motile microorganisms paves the way to diverse environmental and healthcare applications	[305]
	Fei Liu et al.	ExoTIC (exosome total isolation chip)	It is simple, easy-to-use, modular, which facilitates high-yield and high-purity EV (extracellular vesicle) isolation from biofluids	ExoTIC achieves an EV yield ~ 4–1000-fold higher than that with UC (ultracentrifugation), and EV-derived protein. microRNA levels are well-correlated between the two methods Authors utilized ExoTIC to isolate EVs from clinical cancer patient samples, including plasma, urine, and lavage, demonstrating the device’s broad applicability to cancers and other diseases	[306]
Tissue penetration	SaharJafari et al.	Magnetic particle drilling	Authors performed experiments with mouse cadavers that received 250 nm-wide intra-nasal magnetic rods intra-nasally under different combinations of external magnetic fields They found that the application of helical dynamic gradients to the particles (i.e., both rotational and linear) improved transport from the nose into the brain, as compared to linear magnetic gradients alone	This work illustrates the potential of using mechanical stimulation of neural tissue via unthreaded micro/nanorobots No particle track was observed in the brain after drilling, suggesting that the particles travel individually without causing brain damages, consistent with earlier studies in brain slices	[307]
	Juho Pokki et al.	cobalt–nickel microrobots	Coated and uncoated microrobots were investigated for their corrosion properties, and solutions containing coated and uncoated microrobots were tested for cytotoxicity by monitoring NIH3T3 cell viability In vivo tests inside rabbit eyes were performed using coated microrobots	The biocompatibility of micro-/nanorobot was enhanced by using a polypyrrole coating, presenting minimal inflammatory response in comparison with the noncoated counterpart Coated microrobots have the potential to facilitate a new generation of surgical treatments, diagnostics and drug delivery techniques, when implantation in the ocular posterior segment becomes possible	[308]
	Fernando Soto et al.	Acoustically triggered micro_x005fcannons (Mc)	Hollow conically shaped microcannon structures have been synthesized electrochemically and fully loaded with nanobullets made of silica or fluorescent micro_x005fspheres, and perfluorocarbon emulsions, embedded in a gel matrix stabilizer Applying a focused ultrasound pulse to the spontaneous vaporization of the perfluoro-carbon emulsions within the microcannon results in the rapid ejection of the nanobullets	The acoustic microcannons were able to deliver nanoparticles into phantom tissue, reaching a penetration length of ~ 20 µm This acoustic-microcannon approach could be translated into advanced microscale ballistic tools, capable of efficient loading and firing of multiple cargoes, offer improved accessibility to targeted locations and enhances tissue penetration properties	[309]
Intracellular delivery	Fernando Soto et al.	Nanoshell	Such shell-shaped nanomotors display highly efficient acoustic propulsion at the nanoscale by converting the ambient acoustic energy into mechanical motion Nanoshell motors exhibit a different propulsion behavior than that predicted by recent theoretical and experimental models for acoustically-propelled nanomotors	It was demonstrated the practical applications of the new nanoshell motors, including “on-the-move” capture and the transport of multiple cargoes and internalization and movement inside live MCF-7 cancer cells These structures provided higher cargo loading capacity as compared to previously described nanowires used for cellular internalization	[310]
	Xiangyu Jiao et al.	Janus nanocarrier (JNs)	Such a Janus nanocarrier with an Au surface could achieve efficient NIR propulsion, which are helpful for enhancing interactions with cells This nanocarrier could achieve deep tumor penetration by thermo-mechanical percolating cytomembranes and sequentially on–off controlled release	This system integrates the functions of active seeking, cytomembranes percolating, and on–off controlled release in one nanocarrier, which further improves the utilization of nanocarriers, and reduces the side effects of drugs These JNs achieve deep tumor penetration and are expected to reduce the side effects of nanocarriers and drugs	[311]
	Seungmin Lee et al.	Needle-type microrobot	The MRs were fabricated by 3D laser lithography and Ni/TiO2 layers were coated by physical vapor deposition The translational velocity of the MR is 714 μm/s at 20 mT and affixed to the target MT under the control of a rotating external magnetic field	Drug release from the paclitaxel (PTX)-loaded MR was characterized to determine the efficiency of targeted drug delivery This study demonstrated the utility of the proposed needle-type MR for targeted drug delivery to MT with various flow rates in vitro physiological fluidic environments	[312]
Biofilm degradation	Morgan M Stanton et al.	Magnetosopirrillum gryphiswalense (MSR-1)	MSR-1 can be integrated with drug-loaded mesoporous silica microtubes to build controllable micro-swimmers (biohybrids) capable of delivering antibiotics to target an infectious biofilm Under guidance of an external magnetic field controllable swimming power of the MSR-1 cells, the biohybrids are directed to and forcefully pushed into matured Escherichia coli (E. coli) biofilms	A bio-hybrid micro/nanorobot, composed of the integration of magnetotactic bacteria (MSR-1) with mesoporous silica loaded with ciprofloxacin (antibiotic), was explored to apply mechanical stress to E. coli biofilm Release of the antibiotic, ciprofloxacin, was triggered by the acidic microenvironment of the biofilm, ensuring an efficient drug delivery system	[313]
	Geelsu Hwang et al.	Catalytic antimicrobial robots (CARs)	CARs exploit iron oxide nanoparticles (NPs) with dual catalytic-magnetic functionality that 1) generates bactericidal free radicals, 2) breakdown the biofilm exopolysaccharide (EPS) matrix, and 3) remove the fragmented biofilm debris via an external magnetic field-driven robotic assembly	This robotic platform served to swept and remove biofilms over a flat surface, through a blocked capillary tube and to clean biofilms inside an interior tooth model These ‘kill-degrade-and-remove’ CARs systems could have significant impact in fighting persistent biofilm infections and in mitigating biofouling of medical devices and diverse surfaces	[314]