Magnetically Mixing Magnetic Beads for Dispensing: Large Volumes in a Bottle

Stir Elements, Stirrers

V&P Scientific is known for solving challenging mixing applications… We’ve done it again!

We have several methods for magnetically mixing magnetic beads while dispensing to tubes or microplates from a container of concentrated stock.

Starting small, one such method would be manually dispensing magnetic beads using a single pipette tip from a 1.5 ml tube with a Stainless Steel Stir Stix VP 735-2. The magnetic stainless steel of the VP 735-2 is too weak to pull the magnetic beads out of solution but can still be moved by a small magnetic stirrer such as V&P’s VP 710K.

Moving from small to medium size volumes, magnetic bead dispensing can be accomplished from 15 ml and 50 ml tubes with automated microplate dispensing instruments such as a Formulatrix Mantis or a ThermoScientific MultiDrop.

Also in the medium volume range from 25 to 350 ml, multichannel pipettes (manual or automated) can be used to dispense magnetic beads from V&P’s Bubble Paddle Reservoirs.

But how to mix the larger volumes used in cases where large batches of magnetic beads are being prepared and then dispensed?

V&P Scientific introduces Magnetic Mixing of Magnetic Beads in a 500ml bottle with our VP 710D3 MultiStirrus in “conventional stir plate mode” and one of our “standard” PTFE-Encapsulated Magnetic Stir Bars, VP 776-10-80!

Magnetic Stirrer VP 710D2 with VP 710D2-3 Accessory Stand

PTFE Alnico Magnetic Stir Bars, VP 776-10-80

PTFE Alnico Magnetic Stir Bars, VP 776-10-80C

Because of the thickness of the PTFE around the not-so-strong Alnico magnetic core, the magnetic beads that do collect on the ends of the bar are easily spun off, within seconds, once the VP 710D3 MultiStirrus Stir Plate is turned on.

And after the Magnetic Stir Bar is removed from the mixed solution, the only beads on the bar are held there by surface tension of the buffer! See below how easily they wash off with a small amount of buffer!

The advantage of using our VP 710D3 MultiStirrus Stir Plate? It offers better magnetic coupling to our Alnico stir bars so that even viscous and concentrated magnetic bead solutions can be mixed in larger volumes.

VP 711D-1 Stir Element: Good Chemical Resistance But Not Perfect

Viscosity Reference

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Drop-seq Single-Cell RNA-Seq Protocol

Elevate Your Drug Development Workflow with Our Novel SpinVessel®

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Magnetically Mixing Magnetic Beads for Dispensing: Large Volumes in a Bottle

VP 711D-1 Stir Element: Good Chemical Resistance But Not Perfect

V&P Partners with Bioz

Since its founding in 1979 by Dr. Patrick Cleveland and his wife Victoria, V&P’s goal has been to provide the best engineered and most innovative research equipment available.

Company

Products

Hydrophobic Coated vs Non-Coated Pin Transfers

Solid Pin Delivery Data For Aqueous Solutions In 96 Format With Uncoated And /Ah Hydrophobic Coated Pins

Pin	Description		nl Transferred	CV%
0.229 mm diameter (FP9)	Total Pin	Uncoated	7.41	2.4
		Hydrophobic	7.46	5.4
0.229 mm diameter (FP9)	Hanging Drop	Uncoated	N/A	N/A
		Hydrophobic	2.09	3.8
0.457 mm diameter (FP1)	Total Pin	Uncoated	33.48	3.2
		Hydrophobic	28.17	7.5
0.457 mm diameter (FP1)	Hanging Drop	Uncoated	16.96	4.5
		Hydrophobic	8.51	0.8
0.787 mm diameter (FP3)	Total Pin	Uncoated	87.32	3.9
		Hydrophobic	77.4	3.9
0.787 mm diameter (FP3)	Hanging Drop	Uncoated	48.77	1.2
		Hydrophobic	43.05	9.4
1.19 mm diameter (VP 409 & VP 386)	Total Pin	Uncoated	247.22	2.8
		Hydrophobic	192.67	2.6
1.19 mm diameter (VP 409 & VP 386)	Hanging Drop	Uncoated	76.35	1.6
		Hydrophobic	108.4	2.8
1.58 mm diameter (VP 408 & VP 384)	Total Pin	Uncoated	273.5	4.6
		Hydrophobic	259.25	3.1
1.58 mm diameter (VP 408 & VP 384)	Hanging Drop	Uncoated	201.93	5
		Hydrophobic	170.04	7.5

Transfer Of Horseradish Peroxidase In Tris Buffered Saline With Pin Tools

Conclusion

Coating pins will reduce the total amount of liquid transferred and also reduce the amount of non-specific binding to the stainless-steel pins. If the substance you are transferring has high non-specific binding this will be an important factor in selecting your pins.

Slot Pin Delivery Data For Aqueous Solutions In 96 Format With Uncoated And /Ah Hydrophobic Coated Pin

Pin	Description		nl Transferred	CV%
0.229 mm diameter (FP9)	Total Pin	Uncoated	7.41	2.4
		Hydrophobic	7.46	5.4
0.229 mm diameter (FP9)	Hanging Drop	Uncoated	N/A	N/A
		Hydrophobic	2.09	3.8
0.457 mm diameter (FP1)	Total Pin	Uncoated	33.48	3.2
		Hydrophobic	28.17	7.5
0.457 mm diameter (FP1)	Hanging Drop	Uncoated	16.96	4.5
		Hydrophobic	8.51	0.8
0.787 mm diameter (FP3)	Total Pin	Uncoated	87.32	3.9
		Hydrophobic	77.4	3.9
0.787 mm diameter (FP3)	Hanging Drop	Uncoated	48.77	1.2
		Hydrophobic	43.05	9.4
1.19 mm diameter (VP 409 & VP 386)	Total Pin	Uncoated	247.22	2.8
		Hydrophobic	192.67	2.6
1.19 mm diameter (VP 409 & VP 386)	Hanging Drop	Uncoated	76.35	1.6
		Hydrophobic	108.4	2.8
1.58 mm diameter (VP 408 & VP 384)	Total Pin	Uncoated	273.5	4.6
		Hydrophobic	259.25	3.1
1.58 mm diameter (VP 408 & VP 384)	Hanging Drop	Uncoated	201.93	5
		Hydrophobic	170.04	7.5

Transfer Of Horseradish Peroxidase In Tris Buffered Saline With Pin Tools

Conclusion

Although the slots in the pin are a precise volume, the liquid that is transferred is usually more. The reason for this is due to the surface tension of the liquid causing the liquid in the slot to “bow out” thus increasing the volume of the liquid in the slot. If is important for you to transfer exactly a certain volume we can make custom slots to match the surface tension characteristics of your liquid

Liquid Surface Tension

Effect Of DNA Or BSA Concentration On Slot Pin Transfers Of Uncoated And Hydrophobic Coated Pins (FP3CS500)

Solvent/Sample	Concentration	CV%	nl FITC Transferred	CV%	nl FITC Transferred
		Uncoated	Uncoated	Hydrophobic Coated	Hydrophobic Coated
DMSO (-)	0	8.1	353.42	7.5	298.72
DMSO + DNA (mg/ml)	0.5	6.6	497.21	6.6	435.86
	0.25	9	432.49	4.1	391.93
	0.125	8.9	363.64	0.9	344.75
	0.0625	2.3	381.86	2	331.68
	0.0313	1.5	378.03	4.4	331.71
	0.0156	1.2	357.52	1.4	329.03
Tris (-)	0	4.9	577.31	7.2	493.53
Tris + DNA (mg/ml)	0.5	4.5	540.53	1.1	477.5
	0.25	4.6	518.21	6.1	456.75
	0.125	15.8	583.25	4.1	438.82
	0.0625	4.2	551.17	3.1	433.69
	0.0313	4.4	536.66	2.3	458.37
	0.0156	2.9	528.53	1.2	441.1
Tris + BSA (%)	4	5.4	462.13	11	409.27
	1	4	452.86	2.7	426.58
	0.25	11.7	456.45	1.3	408.72
	0.0625	1.1	445.22	6.5	393.07
	0.0156	3.7	462.85	3.9	430.2
	0.0039	1.5	493.54	2.2	437.29
	0.001	2.9	504.25	0.7	475.96

Conclusions

1. Increasing the concentration of DNA (sheared salmon sperm) to .25 mg/ml significantly increases the volume of DMSO liquid transferred for both coated and uncoated FP3S500 Slot Pins.
2. Increasing the concentration of DNA does not significantly increase the volume of Tris buffer (aqueous) transferred by both coated and uncoated FP3S500 Slot Pins.
3. Increasing the concentration of BSA (Bovine Serum Albumin) significantly decreases the volume of Tris buffer transferred by both coated and uncoated FP3S500 Slot Pins.
4. Hydrophobic coated FP3S500 Slot Pins transferred less DMSO – DNA and less Tris DNA and less Tris BSA than the uncoated FP3S500 Slot Pins.
5. Both coated and uncoated FP3S500 pins transfer significantly more aqueous solution than DMSO.

Effect Of DNA Or BSA Concentration On Slot Pin Transfers Of Uncoated And Hydrophobic Coated Pins (FP1CS50)

Solvent/Sample	Concentration	CV%	nl FITC Transferred	CV%	nl FITC Transferred
		Uncoated	Uncoated	Hydrophobic Coated	Hydrophobic Coated
DMSO (-)	0	4.2	49.38	2.1	49.31
DMSO + DNA (mg/ml)	0.5	4.9	51.24	2.6	56.79
	0.25	1.7	50.2	1.2	49.53
	0.125	1.5	51.27	2.3	49.77
	0.0625	2.2	49.34	4.1	48.19
	0.0313	1.2	49.03	0.2	50.23
	0.0156	2.4	45.9	1.4	46.64
Tris (-)	0	2.6	89.51	2.9	91.34
Tris + DNA (mg/ml)	0.5	7	77.11	0.6	84.62
	0.25	3.9	82.22	1.6	84.89
	0.125	3.9	85.42	1	85.08
	0.0625	1.5	85.36	2.8	85.03
	0.0313	2	84.52	3	88.19
	0.0156	2.6	82.92	2.8	83.2

Conclusions

1. In contrast to the FP3S500 data, increasing the concentration of DNA to .25 mg/ml does not significantly increase the volume of DMSO liquid transferred for both coated and uncoated FP1S50 Slot Pins.
2. Increasing the concentration of DNA does not significantly increase the volume of Tris buffer (aqueous) transferred by both coated and uncoated FP1S50 Slot Pins.
3. In contrast to the FP3S500 data, FP1S50 coated pins transferred about the same volume of DNA at all concentrations as did uncoated pins.
4. Both coated and uncoated FP1S50 pins transfer significantly more aqueous solution than DMSO.
5. The differences between the FP3S500 and the FP1S50 pin may be due to the different pin diameter’s effect on contact angle and therefore on the “wetting” of the pin. See the diagram on the link to / ah energy system.

Pin	Description		nl Transferred	CV%
0.229 mm diameter (FP9)	Total Pin	Uncoated	7.41	2.4
		Hydrophobic	7.46	5.4
0.229 mm diameter (FP9)	Hanging Drop	Uncoated	N/A	N/A
		Hydrophobic	2.09	3.8
0.457 mm diameter (FP1)	Total Pin	Uncoated	33.48	3.2
		Hydrophobic	28.17	7.5
0.457 mm diameter (FP1)	Hanging Drop	Uncoated	16.96	4.5
		Hydrophobic	8.51	0.8
0.787 mm diameter (FP3)	Total Pin	Uncoated	87.32	3.9
		Hydrophobic	77.4	3.9
0.787 mm diameter (FP3)	Hanging Drop	Uncoated	48.77	1.2
		Hydrophobic	43.05	9.4
1.19 mm diameter (VP 409 & VP 386)	Total Pin	Uncoated	247.22	2.8
		Hydrophobic	192.67	2.6
1.19 mm diameter (VP 409 & VP 386)	Hanging Drop	Uncoated	76.35	1.6
		Hydrophobic	108.4	2.8
1.58 mm diameter (VP 408 & VP 384)	Total Pin	Uncoated	273.5	4.6
		Hydrophobic	259.25	3.1
1.58 mm diameter (VP 408 & VP 384)	Hanging Drop	Uncoated	201.93	5
		Hydrophobic	170.04	7.5

Aqueous Transfer with Solid Pins

Hydrophobic coating pins will reduce the total amount of aqueous HRP liquid transferred and also reduce the amount of non-specific binding to the stainless-steel pins. If the substance you are transferring has high non-specific binding this will be an important factor in selecting your pins.

Pin diameter also has an effect on the degree of reduction of liquid transfer with hydrophobic coating as the smaller the diameter the less the reduction of transfer. This is most likely due to the curvature of the pin affecting the wetting contact angle

Pin	Description			nl Transferred	CV%
0.457 mm diameter (FP1)	6 nl Slot	Total Pin*	Uncoated	25.6	10.8
			Hydrophobic	N/A	N/A
	10 nl Slot	Total Pin*	Uncoated	23.36	6.1
			Hydrophobic	25.85	6.9
	50 nl Slot	Total Pin*	Uncoated	67.83	2.5
			Hydrophobic	N/A	N/A
0.787 mm diameter (FP3)	100 nl Slot	Total Pin*	Uncoated	180.32	7.2
			Hydrophobic	205.84	5.5
	200 nl Slot	Total Pin*	Uncoated	277.82	4.9
			Hydrophobic	287.3	3.8
	500 nl Slot	Total Pin*	Uncoated	581.16	5.2
			Hydrophobic	555.69	3

DMSO Transfer with Slot Pins

Hydrophobic coating pins will slightly increase the total amount of DMSO FITC liquid transferred.

Pin	Description		nl Transferred	CV%
0.787 mm diameter (FP3)	100 nl Slot Total Pin, Including Slot	Uncoated	195.69	1.6
		Hydrophobic	170.2	2.9
0.787 mm diameter (FP3)	100 nl Slot, Slot Only	Uncoated	149.67	4.9
		Hydrophobic	129.61	7.6
0.787 mm diameter (FP3)	200 nl Slot Total Pin, Including Slot	Uncoated	269.77	1.9
		Hydrophobic	228.62	17.1
0.787 mm diameter (FP3)	200 nl Slot, Slot Only	Uncoated	237.52	8.9
		Hydrophobic	186.9	5.9

Aqueous Transfer with Slot Pins

Although the slots in the pin are a precise volume, the liquid that is transferred is usually more because of the volume carried on the sides of the pins.

As seen with other aqueous data the amount transferred on hydrophobic coated Slot pins is less than on uncoated Solid or Slot pins. Thus Hydrophobic coating has the most effect on aqueous transfers.

Aqueous Solutions Pin Transfer Volumes Ranges

Aqueous Solutions on Uncoated Pins in 96 Format Microplates(1)

Pin Type	Pin Diameter(mm)	Shape	96 Format Low Range(nL)²	96 Format High Range(nL)²
FP9	0.229	Solid	13	39
FP8	0.356	Solid	15	37
FP1	0.457	Solid	22	61
FP1S6	0.457	6nL Slot	34	67
FP1S10	0.457	10nL Slot	39	74
FP1S50	0.457	50nL Slot	90	124
FP3	0.787	Solid	93	213
FP3S100	0.787	100nL Slot	213	334
FP3S200	0.787	200nL Slot	311	449
FP3S500	0.787	500nL Slot	515	671
FP4	0.914	Solid	126	289
Footnotes: (1) Delivery volume range is determined by speed of withdrawal from source liquid: Z-Speed Range = 1.5-30 mm/sec, slow speed = low volume delivery range, fast speed = high volume delivery range (2) 200ul source plate volume per well

Aqueous Solutions on Hydrophobic Pins in 96 Format Microplates(1)

Pin Type	Pin Diameter(mm)	Shape	96 Format Low Range(nL)²	96 Format High Range(nL)²
FP9	0.229	Solid	13	38
FP8	0.356	Solid
FP1	0.457	Solid	23	60
FP1S6	0.457	6nL Slot	33	67
FP1S10	0.457	10nL Slot	40	75
FP1S50	0.457	50nL Slot	86	119
FP3	0.787	Solid	76	209
FP3S100	0.787	100nL Slot	188	324
FP3S200	0.787	200nL Slot	288	436
FP3S500	0.787	500nL Slot	473	649
FP4	0.914	Solid
Footnotes: (1) Delivery volume range is determined by speed of withdrawal from source liquid: Z-Speed Range = 1.5-30 mm/sec, slow speed = low volume delivery range, fast speed = high volume delivery range (2) 200ul source plate volume per well

Aqueous Solution on E-Clip, Uncoated Pins(1)

Pin Type	Pin Diameter(mm)	Shape	Low Range(nL)²	High Range(nL)²
FP	1.58	Solid Pointed	175	594
FPS.5	1.58	500nL Slot	524	962
FPS	1.58	1000nL Slot	1056	1476
FPS2	1.58	2000nL Slot	1739	2174
FPS5	1.58	5000nL Slot	5150	4953
FP6	1.58	Solid Flat	465	960
FP6S.5	1.58	500nL Slot	934	1445
FP6S	1.58	1000nL Slot	1396	1930
FP6S2	1.58	2000nL Slot	2072	2637
FP6S5	1.58	5000nL Slot	4820	4693
Footnotes:(1) Delivery volume range is determined by speed of withdrawal from source liquid: Z-Speed Range = 1.5-30 mm/sec, slow speed = low volume delivery range, fast speed = high volume delivery range (2) 200ul source plate volume per well for 96 Format and 75ul source plate volume per well for 384 Format

DMSO Pin Transfer Volume Range Charts

Uncoated Pins in 96 and 384 Format Microplates(1)

Pin Type	Pin Diameter(mm)	Shape	96 Format Low Range(nL)²	96 Format High Range(nL)²	384 Format Low Range(nL)³	384 Format High Range(nL)³
FP9	0.229	Solid	4	10	3	8
FP8	0.35	Solid	13	26	6	18
FP1	0.457	Solid	18	43	11	31
FP1S6	0.457	6nL Slot	24	49	15	34
FP1S10	0.457	10nL Slot	30	54	21	40
FP1S20	0.457	20nL Slot	37	61	27	46
FP1S30	0.457	30nL Slot	46	68	35	54
FP1S40	0.457	40nL Slot	57	78	45	63
FP1S50	0.457	50nL Slot	70	90	56	75
FP3	0.787	Solid	67	139	29	79
FP4	0.91	Solid	94	197	34	98
FP3S100	0.787	100nL Slot	175	241	114	163
FP3S200	0.787	200nL Slot	280	332	203	250
FP3S500	0.787	500nL Slot	535	559	427	464
FP4S1000	0.91	1000nL Slot	940	1011	704	800
FP4S2000	0.91	2000nL Slot	1518	1608	1277	1362
Footnotes: (1) Delivery volume range is determined by speed of withdrawal from source liquid: Z-Speed Range = 1.5-30 mm/sec, slow speed = low volume delivery range, fast speed = high volume delivery range (2) 200ul source plate volume per well (3) 75ul source plate volume per well

Hydrophobic-coated Pins in 96 and 384 Format Microplates(1)

Pin Type	Pin Diameter (mm)	Shape	96 Format Low Range(nL)²	96 Format High Range(nL)²	384 Format Low Range(nL)³	384 Format High Range(nL)³
FP9H	0.229	Solid	4	10	3	8
FP8H	0.35	Solid	9	24	6	17
FP1H	0.457	Solid	15	39	9	27
FP1S6H	0.457	6nL Slot	23	49	14	32
FP1S10H	0.457	10nL Slot	29	53	20	38
FP1S20H	0.457	20nL Slot	35	59	26	43
FP1S30H	0.457	30nL Slot	47	69	35	53
FP1S40H	0.457	40nL Slot	54	75	41	58
FP1S50H	0.457	50nL Slot	69	90	57	73
FP3H	0.787	Solid	67	134	27	76
FP4H	0.91	Solid	95	189	32	102
FP3S100H	0.787	100nL Slot	170	227	108	164
FP3S200H	0.787	200nL Slot	266	320	190	239
FP3S500H	0.787	500nL Slot	520	542	416	456
FP4S1000H	0.91	1000nL Slot	932	1000	741	805
FP4S2000H	0.91	2000nL Slot	1571	1638	1351	1423
Footnotes: (1) Delivery volume range is determined by speed of withdrawal from source liquid: Z-Speed Range = 1.5-30 mm/sec, slow speed = low volume delivery range, fast speed = high volume delivery range (2) 200ul source plate volume per well (3) 75ul source plate volume per well

E-Clip, Uncoated Pins, for 96 and 384 Format Microplates(1)

Pin Type	Diameter (mm)	Shape	96 Format Low Range(nL)²	96 Format High Range(nL)²	384 Format Low Range(nL)³	384 Format High Range(nL)³
FP	1.58	Solid Pointed	147	411	168	395
FPS.5	1.58	500nL Slot	442	704	631	843
FPS	1.58	1000nL Slot	893	1130	1343	1498
FPS2	1.58	2000nL Slot	1911	2038	2607	2767
FPS5	1.58	5000nL Slot	3908	4296	5180	5253
FP6	1.58	Solid Flat	323	674	154	398
FP6S.5	1.58	500nL Slot	734	1042	855	1053
FP6S	1.58	1000nL Slot	1210	1500	1638	1717
FP6S2	1.58	2000nL Slot	2299	2384	2787	3068
FP6S5	1.58	5000nL Slot	4329	4656	5237	5245
Footnotes:(1) Delivery volume range is determined by speed of withdrawal from source liquid: Z-Speed Range = 1.5-30 mm/sec, slow speed = low volume delivery range, fast speed = high volume delivery range (2) 200ul source plate volume per well (3) 75ul source plate volume per well

V&P Scientific is known for solving challenging mixing applications… We’ve done it again!

Related Posts

VP 711D-1 Stir Element: Good Chemical Resistance But Not Perfect

Viscosity Reference

How Gentle is the SpinVessel®?

Keeping Cells in Uniform Suspension For A 384 Pipettor

Drop-seq Single-Cell RNA-Seq Protocol

Recent Posts

Elevate Your Drug Development Workflow with Our Novel SpinVessel®

Streamlining Protein Science Workflows: Cost-Effective MagWash® for Automating and Enhancing Protein Purification Processes

Magnetically Mixing Magnetic Beads for Dispensing: Large Volumes in a Bottle

VP 711D-1 Stir Element: Good Chemical Resistance But Not Perfect

V&P Partners with Bioz

Company

Products

Hydrophobic Coated vs Non-Coated Pin Transfers

Solid Pin Delivery Data For Aqueous Solutions In 96 Format With Uncoated And /Ah Hydrophobic Coated Pins

Conclusion

Slot Pin Delivery Data For Aqueous Solutions In 96 Format With Uncoated And /Ah Hydrophobic Coated Pin

Conclusion

Liquid Surface Tension

Effect Of DNA Or BSA Concentration On Slot Pin Transfers Of Uncoated And Hydrophobic Coated Pins (FP3CS500)

Conclusions

Effect Of DNA Or BSA Concentration On Slot Pin Transfers Of Uncoated And Hydrophobic Coated Pins (FP1CS50)

Conclusions

Aqueous Transfer with Solid Pins

DMSO Transfer with Slot Pins

Aqueous Transfer with Slot Pins

Withdrawl Speeds Impact on Volume Transfer

Solid Pins More affected by Source Plate Volume

Volume Transferred For FP1 Pins (Uncoated) In 96 And 384 Formats

Volume Transferred For FP3 Pins (Uncoated) In 96 And 384 Formats

Aqueous Solutions Pin Transfer Volumes Ranges

Aqueous Solutions on Uncoated Pins in 96 Format Microplates(1)

Aqueous Solutions on Hydrophobic Pins in 96 Format Microplates(1)

Aqueous Solution on E-Clip, Uncoated Pins(1)

DMSO Pin Transfer Volume Range Charts

Uncoated Pins in 96 and 384 Format Microplates(1)

Hydrophobic-coated Pins in 96 and 384 Format Microplates(1)

E-Clip, Uncoated Pins, for 96 and 384 Format Microplates(1)