Table 1 Carbon dots and their manufacturing techniques for the healing of bone defects

Hydrothermal treatment

HAP-CDs

Hydroxyapatite

20-30nm

Strong cell adhesion and alkaline phosphatase activity

[54]

-

CG- CDs

Collagen-genipin

6-10nm

Promote differentiation of BMSCs to chondrocytes and promote cartilage regeneration

[57]

Hydrothermal cum co-precipitation

HAP-NCDs

Hydroxyapatite

85-200nm

Increased expression of osteogenic-related transcription factor 2, alkaline phosphatase, and osteocalcin

Increased bone density

[58]

Microwave-assisted pyrolysis

MiR-CDs

MiR-2861, Ascorbic acid, PEI

~2.5nm

Promotes osteogenic differentiation

[59]

Hydrothermal treatment

Zn-CDs

Zn²⁺

5.25nm

Induce osteoblast differentiation

[60]

Hydrothermal treatment

Zn-CDs

Zn²⁺

1.7-2.5nm

Promotes bone regeneration

Has good osteogenic activity

[61]

-

SMCC-CDs

Sulfosuccinimidyl-4-(N-maleimidomethyl) cyclohexane-1-carboxylate (sulfo-SMCC)

13-22nm

Promotes differentiation of bMSCs to chondrocytes

Promotes cartilage regeneration in vivo

[62]

Hydrothermal treatment

Fe-CDs

Super-paramagnetic iron oxide nanoparticles

40-60nm

Promotes osteochondral differentiation

[63]

Microwave-assisted

Ascorbic acid- CDs

Ascorbic acid

2-3nm

Activate the PERK-eIF2α-ATF4 signaling pathway

Increased BSP and OCN expression

Promote pre-osteoblast differentiation and bone regeneration

[64]

Hydrothermal treatment

M-CDs

Metformin

3.76nm

Promotes bone marrow mesenchymal stem cells (BMSCs), alkaline phosphatase (ALP) activity, calcium deposition nodule formation, and expression of osteogenic genes and proteins

[65]

Microwave

CS-NHA-CDs

Chitosan, Nano-hydroxyapatite

5nm

Enhanced adhesion and osteogenic differentiation of rBMSCs, good antibacterial effect

Promoted the formation of vascularized bone tissue

[56]

Hydrothermal treatment

SPIC-CDs

SVVYGLR, PRGDSGYRGDS, IPP, CGGKVGKACCVPTKLSPISVLYK

2.2-4.8nm

Stimulates osteoblast adhesion, proliferation and differentiation, and induces angiogenesis

[53]

Hydrothermal treatment

Citric acid-CDs

Citric acid

-

Upregulate the expression of osteoblast gene markers ALP, RUNX2, OCN and BSP to promote matrix mineralization and thus promote osteogenic differentiation of rBMSCs

[55]

Hydrothermal treatment

PCL-CP-CDs

PCL, captopril

~10nm

Enhanced activity, adhesion, alkaline phosphatase activity and mineralization

[66]

Hydrothermal treatment

PCL/PVA-TCP3-CDs

PCL, PVA, calcium phosphate

5-7nm

Significantly increased alkaline phosphatase activity and cell proliferation rate

[67]

Microwave-assisted hydrothermal treatment

WS2 HJS-CDs

Heterojunction, WS2 nanosheets

9.3-11.9nm

Significantly promotes osteogenic differentiation and significantly upregulates the expression of bone-related genes

[68]

Hydrothermal treatment

OH-CDs

Hydroxyl

4nm

Scavenges free radical groups and promotes cell proliferation

[69]

Hydrothermal treatment

AA-CDs

Adenosine, aspirin

2-5nm

Induced differentiation of hBMSCs toward osteogenesis

[70]

Hydrothermal treatment

PLA-CDs

PLA

3-7nm

Promotes cell proliferation, increased bone mineralization, and increased osteogenic differentiation

[71]

Microwave-assisted

p-CDs

Positive charge

3.6-5.8nm

Enhance antibacterial effect

[72]

Microwave-assisted

n-CDs

Negative charge

1.7-4.1nm

Promote osteogenic differentiation

[72]

Hydrothermal treatment

CDs

-

~10nm

High affinity with bone

[73]

Hydrothermal treatment

Mg-CDs

Mg²⁺

Up to 39.8nm with increasing temperature

Increase alkaline phosphatase (ALP) activity

Upregulate the expression of osteogenic-related genes: Runx2, OSX, Col1a1, OCN

[74]

Hydrothermal treatment

BMP-2-CDs

BMP-2

7-10nm

Enhanced MG-63 cell biology and osteoinductive effects

[75]

Hydrothermal treatment

2-CDs

2-citric acid, poly (ethylene glycol) monomethyl ether (MW 550 Da), N, N-dimethylethylenediamine

16.8-18.6nm

Promotes cell proliferation (transforming growth factor-β) and cartilage matrix deposition (glycosaminoglycan, type II collagen); Inhibits undesirable type I and type X collagen deposition

[76]